Cisco IOS XR MPLS Configuration Guide for the Cisco CRS Router, Release 5.1.x
Implementing MPLS Label Distribution Protocol
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Implementing MPLS Label Distribution Protocol

Contents

Implementing MPLS Label Distribution Protocol

The Multiprotocol Label Switching (MPLS) is a standards-based solution driven by the Internet Engineering Task Force (IETF) that was devised to convert the Internet and IP backbones from best-effort networks into business-class transport mediums.

MPLS, with its label switching capabilities, eliminates the need for an IP route look-up and creates a virtual circuit (VC) switching function, allowing enterprises the same performance on their IP-based network services as with those delivered over traditional networks such as Frame Relay or ATM.

Label Distribution Protocol (LDP) performs label distribution in MPLS environments. LDP provides the following capabilities:

  • LDP performs hop-by-hop or dynamic path setup; it does not provide end-to-end switching services.

  • LDP assigns labels to routes using the underlying Interior Gateway Protocols (IGP) routing protocols.

  • LDP provides constraint-based routing using LDP extensions for traffic engineering.

Finally, LDP is deployed in the core of the network and is one of the key protocols used in MPLS-based Layer 2 and Layer 3 virtual private networks (VPNs).

Feature History for Implementing MPLS LDP

Release

Modification

Release 2.0

This feature was introduced.

Release 3.0

No modification.

Release 3.2

Support was added for conceptual and configuration information about LDP label advertisement control (Outbound label filtering).

Release 3.3.0

Support was added for these features:
  • Inbound Label Filtering

  • Local Label Allocation Control

  • Session Protection

  • LDP-IGP Synchronization

Release 3.4.0

No modification.

Release 3.4.1

No modification.

Release 3.5.0

Support was added for LDP Auto-configuration.

Release 3.6.0

Support was added for LDP nonstop routing (NSR).

Release 3.7.0

No modification.

Release 3.8.0

The feature LDP IGP Synchronization Process Restart Delay was introduced.

Release 3.9.0

No modification.

Release 4.0.1

Support was added for these features:
  • IP LDP Fast Reroute Loop Free Alternate

  • Downstream on Demand

Release 5.1

Support was added for MPLS over IRB.

Release 5.1.1

The feature MPLS LDP Carrier Supporting Carrier for Multiple VRFs was introduced.

Release 5.3.0

IPv6 Support in MPLS LDP was introduced.

Prerequisites for Implementing Cisco MPLS LDP

These prerequisites are required to implement MPLS LDP:

  • You must be in a user group associated with a task group that includes the proper task IDs. The command reference guides include the task IDs required for each command. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

  • You must be running Cisco IOS XR software.

  • You must install a composite mini-image and the MPLS package.

  • You must activate IGP.

  • We recommend to use a lower session holdtime bandwidth such as neighbors so that a session down occurs before an adjacency-down on a neighbor. Therefore, the following default values for the hello times are listed:
    • Holdtime is 15 seconds.

    • Interval is 5 seconds.

    For example, the LDP session holdtime can be configured as 30 seconds by using the holdtime command.

Information About Implementing Cisco MPLS LDP

To implement MPLS LDP, you should understand these concepts:

Overview of Label Distribution Protocol

LDP performs label distribution in MPLS environments. LDP uses hop-by-hop or dynamic path setup, but does not provide end-to-end switching services. Labels are assigned to routes that are chosen by the underlying IGP routing protocols. The Label Switched Paths (LSPs) that result from the routes, forward labeled traffic across the MPLS backbone to adjacent nodes.

Label Switched Paths

LSPs are created in the network through MPLS. They can be created statically, by RSVP traffic engineering (TE), or by LDP. LSPs created by LDP perform hop-by-hop path setup instead of an end-to-end path.

LDP Control Plane

The control plane enables label switched routers (LSRs) to discover their potential peer routers and to establish LDP sessions with those peers to exchange label binding information.

Figure 1. LDP Control Protocol. This figure shows the control messages exchanged between LDP peers.



LDP uses the hello discovery mechanism to discover its neighbor or peer on the network. When LDP is enabled on an interface, it sends hello messages to a link-local multicast address, and joins a specific multicast group to receive hellos from other LSRs present on the given link. When LSRs on a given link receive hellos, their neighbors are discovered and the LDP session (using TCP) is established.


Note


Hellos are not only used to discover and trigger LDP sessions; they are also required to maintain LDP sessions. If a certain number of hellos from a given peer are missed in sequence, LDP sessions are brought down until the peer is discovered again.


LDP also supports non-link neighbors that could be multiple hops away on the network, using the targeted hello mechanism. In these cases, hellos are sent on a directed, unicast address.

The first message in the session establishment phase is the initialization message, which is used to negotiate session parameters. After session establishment, LDP sends a list of all its interface addresses to its peers in an address message. Whenever a new address becomes available or unavailable, the peers are notified regarding such changes via ADDRESS or ADDRESS_WITHDRAW messages respectively.

When MPLS LDP learns an IGP prefix it allocates a label locally as the inbound label. The local binding between the prefix label is conveyed to its peers via LABEL_MAPPING message. If the binding breaks and becomes unavailable, a LABEL_WITHDRAW message is sent to all its peers, which responds with LABEL_RELEASE messages.

The local label binding and remote label binding received from its peer(s) is used to setup forwarding entries. Using routing information from the IGP protocol and the forwarding information base (FIB), the next active hop is selected. Label binding is learned from the next hop peer, and is used as the outbound label while setting up the forwarding plane.

The LDP session is also kept alive using the LDP keepalive mechanism, where an LSR sends a keepalive message periodically to its peers. If no messages are received and a certain number of keepalive messages are missed from a peer, the session is declared dead, and brought down immediately.

Exchanging Label Bindings

LDP creates LSPs to perform the hop-by-hop path setup so that MPLS packets can be transferred between the nodes on the MPLS network.

Figure 2. Setting Up Label Switched Paths . This figure illustrates the process of label binding exchange for setting up LSPs.



For a given network (10.0.0.0), hop-by-hop LSPs are set up between each of the adjacent routers (or, nodes) and each node allocates a local label and passes it to its neighbor as a binding:

  1. R4 allocates local label L4 for prefix 10.0.0.0 and advertises it to its neighbors (R3).

  2. R3 allocates local label L3 for prefix 10.0.0.0 and advertises it to its neighbors (R1, R2, R4).

  3. R1 allocates local label L1 for prefix 10.0.0.0 and advertises it to its neighbors (R2, R3).

  4. R2 allocates local label L2 for prefix 10.0.0.0 and advertises it to its neighbors (R1, R3).

  5. R1’s label information base (LIB) keeps local and remote labels bindings from its neighbors.

  6. R2’s LIB keeps local and remote labels bindings from its neighbors.

  7. R3’s LIB keeps local and remote labels bindings from its neighbors.

  8. R4’s LIB keeps local and remote labels bindings from its neighbors.

LDP Forwarding

Once label bindings are learned, the LDP control plane is ready to setup the MPLS forwarding plane as shown in the following figure.

Figure 3. Forwarding Setup. Once label bindings are learned, the LDP control plane is ready to setup the MPLS forwarding plane as shown in this figure.



  1. Because R3 is next hop for 10.0.0.0 as notified by the FIB, R1 selects label binding from R3 and installs forwarding entry (Layer 1, Layer 3).

  2. Because R3 is next hop for 10.0.0.0 (as notified by FIB), R2 selects label binding from R3 and installs forwarding entry (Layer 2, Layer 3).

  3. Because R4 is next hop for 10.0.0.0 (as notified by FIB), R3 selects label binding from R4 and installs forwarding entry (Layer 3, Layer 4).

  4. Because next hop for 10.0.0.0 (as notified by FIB) is beyond R4, R4 uses NO-LABEL as the outbound and installs the forwarding entry (Layer 4); the outbound packet is forwarded IP-only.

  5. Incoming IP traffic on ingress LSR R1 gets label-imposed and is forwarded as an MPLS packet with label L3.

  6. Incoming IP traffic on ingress LSR R2 gets label-imposed and is forwarded as an MPLS packet with label L3.

  7. R3 receives an MPLS packet with label L3, looks up in the MPLS label forwarding table and switches this packet as an MPLS packet with label L4.

  8. R4 receives an MPLS packet with label L4, looks up in the MPLS label forwarding table and finds that it should be Unlabeled, pops the top label, and passes it to the IP forwarding plane.

  9. IP forwarding takes over and forwards the packet onward.

LDP Graceful Restart

LDP (Label Distribution Protocol) graceful restart provides a control plane mechanism to ensure high availability and allows detection and recovery from failure conditions while preserving Nonstop Forwarding (NSF) services. Graceful restart is a way to recover from signaling and control plane failures without impacting forwarding.

Without LDP graceful restart, when an established session fails, the corresponding forwarding states are cleaned immediately from the restarting and peer nodes. In this case LDP forwarding restarts from the beginning, causing a potential loss of data and connectivity.

The LDP graceful restart capability is negotiated between two peers during session initialization time, in FT SESSION TLV. In this typed length value (TLV), each peer advertises the following information to its peers:

Reconnect time

Advertises the maximum time that other peer will wait for this LSR to reconnect after control channel failure.

Recovery time

Advertises the maximum time that the other peer has on its side to reinstate or refresh its states with this LSR. This time is used only during session reestablishment after earlier session failure.

FT flag

Specifies whether a restart could restore the preserved (local) node state for this flag.

Once the graceful restart session parameters are conveyed and the session is up and running, graceful restart procedures are activated.

When configuring the LDP graceful restart process in a network with multiple links, targeted LDP hello adjacencies with the same neighbor, or both, make sure that graceful restart is activated on the session before any hello adjacency times out in case of neighbor control plane failures. One way of achieving this is by configuring a lower session hold time between neighbors such that session timeout occurs before hello adjacency timeout. It is recommended to set LDP session hold time using the following formula:

Session Holdtime <= (Hello holdtime - Hello interval) * 3

This means that for default values of 15 seconds and 5 seconds for link Hello holdtime and interval respectively, session hold time should be set to 30 seconds at most.

For more information about LDP commands, see MPLS Label Distribution Protocol Commands module of the Cisco IOS XR MPLS Command Reference for the Cisco CRS Router.

Control Plane Failure

When a control plane failure occurs, connectivity can be affected. The forwarding states installed by the router control planes are lost, and the in-transit packets could be dropped, thus breaking NSF.

Figure 4. Control Plane Failure. This figure illustrates a control plane failure and shows the process and results of a control plane failure leading to loss of connectivity.



  1. The R4 LSR control plane restarts.

  2. LIB is lost when the control plane restarts.

  3. The forwarding states installed by the R4 LDP control plane are immediately deleted.

  4. Any in-transit packets flowing from R3 to R4 (still labeled with L4) arrive at R4.

  5. The MPLS forwarding plane at R4 performs a lookup on local label L4 which fails. Because of this failure, the packet is dropped and NSF is not met.

  6. The R3 LDP peer detects the failure of the control plane channel and deletes its label bindings from R4.

  7. The R3 control plane stops using outgoing labels from R4 and deletes the corresponding forwarding state (rewrites), which in turn causes forwarding disruption.

  8. The established LSPs connected to R4 are terminated at R3, resulting in broken end-to-end LSPs from R1 to R4.

  9. The established LSPs connected to R4 are terminated at R3, resulting in broken LSPs end-to-end from R2 to R4.

Phases in Graceful Restart

The graceful restart mechanism is divided into different phases:

Control communication failure detection
Control communication failure is detected when the system detects either:
  • Missed LDP hello discovery messages

  • Missed LDP keepalive protocol messages

  • Detection of Transmission Control Protocol (TCP) disconnection a with a peer

Forwarding state maintenance during failure

Persistent forwarding states at each LSR are achieved through persistent storage (checkpoint) by the LDP control plane. While the control plane is in the process of recovering, the forwarding plane keeps the forwarding states, but marks them as stale. Similarly, the peer control plane also keeps (and marks as stale) the installed forwarding rewrites associated with the node that is restarting. The combination of local node forwarding and remote node forwarding plane states ensures NSF and no disruption in the traffic.

Control state recovery

Recovery occurs when the session is reestablished and label bindings are exchanged again. This process allows the peer nodes to synchronize and to refresh stale forwarding states.

Recovery with Graceful-Restart

Figure 5. Recovering with Graceful Restart. This figure illustrates the process of failure recovery using graceful restart.



  1. The router R4 LSR control plane restarts.

  2. With the control plane restart, LIB is gone but forwarding states installed by R4’s LDP control plane are not immediately deleted but are marked as stale.

  3. Any in-transit packets from R3 to R4 (still labeled with L4) arrive at R4.

  4. The MPLS forwarding plane at R4 performs a successful lookup for the local label L4 as forwarding is still intact. The packet is forwarded accordingly.

  5. The router R3 LDP peer detects the failure of the control plane and channel and deletes the label bindings from R4. The peer, however, does not delete the corresponding forwarding states but marks them as stale.

  6. At this point there are no forwarding disruptions.

  7. The peer also starts the neighbor reconnect timer using the reconnect time value.

  8. The established LSPs going toward the router R4 are still intact, and there are no broken LSPs.

When the LDP control plane recovers, the restarting LSR starts its forwarding state hold timer and restores its forwarding state from the checkpointed data. This action reinstates the forwarding state and entries and marks them as old.

The restarting LSR reconnects to its peer, indicated in the FT Session TLV, that it either was or was not able to restore its state successfully. If it was able to restore the state, the bindings are resynchronized.

The peer LSR stops the neighbor reconnect timer (started by the restarting LSR), when the restarting peer connects and starts the neighbor recovery timer. The peer LSR checks the FT Session TLV if the restarting peer was able to restore its state successfully. It reinstates the corresponding forwarding state entries and receives binding from the restarting peer. When the recovery timer expires, any forwarding state that is still marked as stale is deleted.

If the restarting LSR fails to recover (restart), the restarting LSR forwarding state and entries will eventually timeout and is deleted, while neighbor-related forwarding states or entries are removed by the Peer LSR on expiration of the reconnect or recovery timers.

Label Advertisement Control (Outbound Filtering)

By default, LDP advertises labels for all the prefixes to all its neighbors. When this is not desirable (for scalability and security reasons), you can configure LDP to perform outbound filtering for local label advertisement for one or more prefixes to one more peers. This feature is known as LDP outbound label filtering, or local label advertisement control.

Label Acceptance Control (Inbound Filtering)

By default, LDP accepts labels (as remote bindings) for all prefixes from all peers. LDP operates in liberal label retention mode, which instructs LDP to keep remote bindings from all peers for a given prefix. For security reasons, or to conserve memory, you can override this behavior by configuring label binding acceptance for set of prefixes from a given peer.

The ability to filter remote bindings for a defined set of prefixes is also referred to as LDP inbound label filtering.


Note


Inbound filtering can also be implemented using an outbound filtering policy; however, you may not be able to implement this system if an LDP peer resides under a different administration domain. When both inbound and outbound filtering options are available, we recommend that you use outbound label filtering.


Local Label Allocation Control

By default, LDP allocates local labels for all prefixes that are not Border Gateway Protocol (BGP) prefixes1. This is acceptable when LDP is used for applications other than Layer 3 virtual private networks (L3VPN) core transport. When LDP is used to set up transport LSPs for L3VPN traffic in the core, it is not efficient or even necessary to allocate and advertise local labels for, potentially, thousands of IGP prefixes. In such a case, LDP is typically required to allocate and advertise local label for loopback /32 addresses for PE routers. This is accomplished using LDP local label allocation control, where an access list can be used to limit allocation of local labels to a set of prefixes. Limiting local label allocation provides several benefits, including reduced memory usage requirements, fewer local forwarding updates, and fewer network and peer updates.


Tip


You can configure label allocation using an IP access list to specify a set of prefixes that local labels can allocate and advertise.


Session Protection

When a link comes up, IP converges earlier and much faster than MPLS LDP and may result in MPLS traffic loss until MPLS convergence. If a link flaps, the LDP session will also flap due to loss of link discovery. LDP session protection minimizes traffic loss, provides faster convergence, and protects existing LDP (link) sessions by means of “parallel” source of targeted discovery hello. An LDP session is kept alive and neighbor label bindings are maintained when links are down. Upon reestablishment of primary link adjacencies, MPLS convergence is expedited as LDP need not relearn the neighbor label bindings.

LDP session protection lets you configure LDP to automatically protect sessions with all or a given set of peers (as specified by peer-acl). When configured, LDP initiates backup targeted hellos automatically for neighbors for which primary link adjacencies already exist. These backup targeted hellos maintain LDP sessions when primary link adjacencies go down.

The Session Protection figure illustrates LDP session protection between neighbors R1 and R3. The primary link adjacency between R1 and R3 is directly connected link and the backup; targeted adjacency is maintained between R1 and R3. If the direct link fails, LDP link adjacency is destroyed, but the session is kept up and running using targeted hello adjacency (through R2). When the direct link comes back up, there is no change in the LDP session state and LDP can converge quickly and begin forwarding MPLS traffic.

Figure 6. Session Protection




Note


When LDP session protection is activated (upon link failure), protection is maintained for an unlimited period time.


IGP Synchronization

Lack of synchronization between LDP and IGP can cause MPLS traffic loss. Upon link up, for example, IGP can advertise and use a link before LDP convergence has occurred; or, a link may continue to be used in IGP after an LDP session goes down.

LDP IGP synchronization synchronizes LDP and IGP so that IGP advertises links with regular metrics only when MPLS LDP is converged on that link. LDP considers a link converged when at least one LDP session is up and running on the link for which LDP has sent its applicable label bindings and received at least one label binding from the peer. LDP communicates this information to IGP upon link up or session down events and IGP acts accordingly, depending on sync state.

In the event of an LDP graceful restart session disconnect, a session is treated as converged as long as the graceful restart neighbor is timed out. Additionally, upon local LDP restart, a checkpointed recovered LDP graceful restart session is used and treated as converged and is given an opportunity to connect and resynchronize.

Under certain circumstances, it might be required to delay declaration of resynchronization to a configurable interval. LDP provides a configuration option to delay declaring synchronization up for up to 60 seconds. LDP communicates this information to IGP upon linkup or session down events.


Note


The configuration for LDP IGP synchronization resides in respective IGPs (OSPF and IS-IS) and there is no LDP-specific configuration for enabling of this feature. However, there is a specific LDP configuration for IGP sync delay timer.


IGP Auto-configuration

To enable LDP on a large number of interfaces, IGP auto-configuration lets you automatically configure LDP on all interfaces associated with a specified IGP interface; for example, when LDP is used for transport in the core network. However, there needs to be one IGP set up to enable LDP auto-configuration.

Typically, LDP assigns and advertises labels for IGP routes and must often be enabled on all active interfaces by an IGP. Without IGP auto-configuration, you must define the set of interfaces under LDP, a procedure that is time-intensive and error-prone.


Note


LDP auto-configuration is supported for IPv4 unicast family in the default VRF. The IGP is responsible for verifying and applying the configuration.


You can also disable auto-configuration on a per-interface basis. This permits LDP to enable all IGP interfaces except those that are explicitly disabled and prevents LDP from enabling an interface when LDP auto-configuration is configured under IGP.

IGP Synchronization Process Restart Delay

In the LDP IGP synchronization process, failures and restarts bear a heavy stress on the network. Multiple IGP synchronization notifications from LDP to IGP, and potential generation of multiple SPF and LSAs are known to effect the CPU load considerably. This results in considerable traffic loss when the LDP process fails.

The LDP IGP Synchronization Process Restart Delay is a feature that enables a process-level delay for synchronization events when the LDP fails or restarts. This delay defers the sending of sync-up events to the IGP until most or all the LDP sessions converge and also allows the LDP to stabilize. This allows the LDP process failure to be less stressful, since IGPs receive all the sync-up events in one bulk. This means that IGP is required to run the SPF and LSAs only one time with an overall view of the sync-up events.


Note


By default the IGP Synchronization Process Restart Delay is disabled and can be enabled by running the configuration command mpls ldp igp sync delay on-proc-restart .


LDP Nonstop Routing

LDP nonstop routing (NSR) functionality makes failures, such as Route Processor (RP) or Distributed Route Processor (DRP) failover, invisible to routing peers with minimal to no disruption of convergence performance. By default, NSR is globally enabled on all LDP sessions except AToM.

A disruption in service may include any of these events:

  • Route processor (RP) or distributed route processor (DRP) failover

  • LDP process restart

  • In-service system upgrade (ISSU)

  • Minimum disruption restart (MDR)


Note


Unlike graceful restart functionality, LDP NSR does not require protocol extensions and does not force software upgrades on other routers in the network, nor does LDP NSR require peer routers to support NSR.


Process failures of active TCP or LDP results in session loss and, as a result, NSR cannot be provided unless RP switchover is configured as a recovery action. For more information about how to configure switchover as a recovery action for NSR, see Configuring Transports module in Cisco IOS XR IP Addresses and Services Configuration Guide for the Cisco CRS Router.

IP LDP Fast Reroute Loop Free Alternate

The IP Fast Reroute is a mechanism that enables a router to rapidly switch traffic, after an adjacent link failure, node failure, or both, towards a pre-programmed loop-free alternative (LFA) path. This LFA path is used to switch traffic until the router installs a new primary next hop again, as computed for the changed network topology.

The goal of LFA FRR is to reduce failure reaction time to 50 milliseconds by using a pre-computed alternate next hop, in the event that the currently selected primary next hop fails, so that the alternate can be rapidly used when the failure is detected.

This feature targets to address the fast convergence ability by detecting, computing, updating or enabling prefix independent pre-computed alternate loop-free paths at the time of failure.

IGP pre-computes a backup path per IGP prefix. IGP selects one and only one backup path per primary path. RIB installs the best path and download path protection information to FIB by providing correct annotation for protected and protecting paths. FIB pre-installs the backup path in dataplane. Upon the link or node failure, the routing protocol detects the failure, all the backup paths of the impacted prefixes are enabled in a prefix-independent manner.

Prerequisites

The Label Distribution Protocol (LDP) can use the loop-free alternates as long as these prerequisites are met:

The Label Switching Router (LSR) running LDP must distribute its labels for the Forwarding Equivalence Classes (FECs) it can provide to all its neighbors, regardless of whether they are upstream, or not.

There are two approaches in computing LFAs:

  • Link-based (per-link)--In link-based LFAs, all prefixes reachable through the primary (protected) link share the same backup information. This means that the whole set of prefixes, sharing the same primary, also share the repair or fast reroute (FRR) ability. The per-link approach protects only the next hop address. The per-link approach is suboptimal and not the best for capacity planning. This is because all traffic is redirected to the next hop instead of being spread over multiple paths, which may lead to potential congestion on link to the next hop. The per-link approach does not provide support for node protection.

  • Prefix-based (per-prefix)--Prefix-based LFAs allow computing backup information per prefix. It protects the destination address. The per-prefix approach is the preferred approach due to its greater applicability, and the greater protection and better bandwidth utilization that it offers.


    Note


    The repair or backup information computed for a given prefix using prefix-based LFA may be different from the computed by link-based LFA.


The per-prefix LFA approach is preferred for LDP IP Fast Reroute LFA for these reasons:

  • Better node failure resistance

  • Better capacity planning and coverage

Features Not Supported

These interfaces and features are not supported for the IP LDP Fast Reroute Loop Free Alternate feature:

  • BVI interface (IRB) is not supported either as primary or backup path.

  • GRE tunnel is not supported either as primary or backup path.

  • In a multi-topology scenerio, the route in topology T can only use LFA within topology T. Hence, the availability of a backup path depends on the topology.

For more information about configuring the IP Fast Reroute Loop-free alternate , see Implementing IS-IS on Cisco IOS XR Software module of the Cisco IOS XR Routing Configuration Guide for the Cisco CRS Router.

Downstream on Demand

This Downstream on demand feature adds support for downstream-on-demand mode, where the label is not advertised to a peer, unless the peer explicitly requests it. At the same time, since the peer does not automatically advertise labels, the label request is sent whenever the next-hop points out to a peer that no remote label has been assigned.

To enable downstream-on-demand mode, this configuration must be applied at mpls ldp configuration mode:

mpls ldp downstream-on-demand with ACL

The ACL contains a list of peer IDs that are configured for downstream-on-demand mode. When the ACL is changed or configured, the list of established neighbors is traversed. If a session's downstream-on-demand configuration has changed, the session is reset in order that the new down-stream-on-demand mode can be configured. The reason for resetting the session is to ensure that the labels are properly advertised between the peers. When a new session is established, the ACL is verified to determine whether the session should negotiate for downstream-on-demand mode. If the ACL does not exist or is empty, downstream-on-demand mode is not configured for any neighbor.

For it to be enabled, the Downstream on demand feature has to be configured on both peers of the session. If only one peer in the session has downstream-on-demand feature configured, then the session does not use downstream-on-demand mode.

If, after, a label request is sent, and no remote label is received from the peer, the router will periodically resend the label request. After the peer advertises a label after receiving the label request, it will automatically readvertise the label if any label attribute changes subsequently.

MPLS LDP Carrier Supporting Carrier for Multiple VRFs

The carrier supporting carrier (CSC) support for MPLS LDP feature enables MPLS label distribution protocol (LDP) to provide CSC support for Layer 3 Virtual Private Networks (L3VPN). To support LDP as label distribution protocol between PE-CE devices in an MPLS CSC L3VPN, LDP is required to operate in multiple Virtual Private Network routing and forwarding (VRF) contexts.

MPLS Carrier Supporting Carrier L3VPN: Introduction

The carrier supporting carrier feature enables one MPLS VPN-based service provider to allow other service providers to use a segment of its backbone network. The service provider that provides the segment of the backbone network to the other provider is called the backbone carrier. The service provider that uses the segment of the backbone network is called the customer carrier.

A backbone carrier offers Border Gateway Protocol and Multiprotocol Label Switching (BGP/MPLS) VPN services. The customer carrier can be either:

  • An Internet service provider (ISP)

  • A BGP/MPLS VPN service provider

In either case, MPLS is run in the backbone network and between the backbone and customer carrier (the PE-CE link).

Figure 7. MPLS Carrier Supporting Carrier L3VPN. This figure illustrates an MPLS CSC L3VPN.



The figure shows two customers, A and X, connecting their remote sites through the backbone carrier. The PE device of the backbone network connects with both customers through MPLS but under different VRFs according to interface-VRF mapping. The MPLS label distribution protocol for PE-CE connectivity can be either BGP or LDP, and requires them to run in a customer VRF context on the PE device.

Benefits of MPLS LDP CSC

The MPLS LDP CSC provides the following benefits to service providers who are backbone carriers and to customer carriers.

Benefits to the Backbone Carrier

  • The backbone carrier can accommodate many customer carriers and give them access to its backbone. The backbone carrier does not need to create and maintain separate backbones for its customer carriers. Using one backbone network to support multiple customer carriers simplifies the backbone carrier's VPN operations. The backbone carrier uses a consistent method for managing and maintaining the backbone network. This is also cheaper and more efficient than maintaining separate backbones.

  • The MPLS LDP CSC feature is scalable. CSC can change the VPN to meet changing bandwidth and connectivity needs. The feature can accommodate unplanned growth and changes. The CSC feature enables tens of thousands of VPNs to be configured over the same network, and it allows a service provider to offer both VPN and internet services.

  • The MPLS LDP CSC feature is a flexible solution. The backbone carrier can accommodate many types of customer carriers. The backbone carrier can accept customer carriers who are ISPs or VPN service providers or both. The backbone carrier can accommodate customer carriers that require security and various bandwidths.

Benefits to the Customer Carriers

  • The MPLS LDP CSC feature removes from the customer carrier the burden of configuring, operating, and maintaining its own backbone. The customer carrier uses the backbone network of a backbone carrier, but the backbone carrier is responsible for network maintenance and operation.

  • Customer carriers who use the VPN services provided by the backbone carrier receive the same level of security that Frame Relay or ATM-based VPNs provide. Customer carriers can also use IPSec in their VPNs for a higher level of security; it is completely transparent to the backbone carrier.

  • Customer carriers can use any link layer technology (SONET, Digital Subscriber Line, Frame Relay, and so on) to connect the CE routers to the PE routers and the PE routers to the P routers. The MPLS LDP CSC feature is link layer independent. The CE routers and PE routers use IP or MPLS to communicate, and the backbone carrier uses MPLS.

  • The customer carrier can use any addressing scheme and still be supported by a backbone carrier. The customer address space and routing information are independent of the address space and routing information of other customer carriers or the backbone provider.

Multiple VRF Support

To support multiple VRFs, IOS XR LDP configuration model is extended to allow VRF submode and per-VRF configuration and feature or interface enabling.

IOS XR LDP process is not distributed nor it is multi-instance, hence the single LDP process services all the configured VRFs. In large scale VRF deployment, it is recommended to enable VRF under LDP with appropriate policies and label filtering.

RSI

To obtain VRF and routing tables’ related information, LDP interacts with the router space infrastructure (RSI) server. For every LDP enabled non-default VRF, LDP registers with RSI to get notifications upon VRF default (IPv4/IPv6) tables getting created or deleted, and populate the LDP VRF database accordingly.

VRF Table ID Database

A new database is added in the LDP process to keep track of all VRFs enabled under LDP. This database holds both active as well as forward-reference VRF records. In addition to serving as an LDP context, each active record of this database also holds VRF’s default (IPv4/IPv6 unicast) table IDs.

VRF-Interface Mapping

To enable LDP on an interface for a given address family under a VRF context , it is required to list interface and its address family explicitly under a LDP VRF submode. LDP does not enforce or check correctness of the interface and VRF mapping at the time of configuration, and hence configuration may be accepted by LDP. The interface with incorrect VRF mapping is not made operational by LDP and remains down from the LDP point of view.

This means that an interface remains LDP operationally down for which either:

  • LDP has not received any address update, or

  • LDP has received update with different table-id (VRF) than configured under LDP.

Also, a user must not configure the same LDP interface under more than one VRF.

Context Isolation

Each active VRF under LDP points to a separate context under which LDP runs. This means that various variables, database, tables, FSM are kept separate in their respective VRF contexts and do not interfere or interact with each other. This allows the LDP to provide per-VRF isolation and support CSC with customers with overlapping addresses or routing information.

Default Context

The default (global) context is enabled at the time of the LDP process startup and remains enabled always. It is not possible to disable IPv4 for the default context. Also, it is required to explicitly enable IPv4 for non-default context. Therefore you can effectively disable IPv4 for non-default context by not configuring it. This means that, it is possible to enable or disable the non-default context under LDP, whereas the same is not possible for a default context.

Restrictions and Recommendations

The following restrictions and recommendations apply to the MPLS LDP CSC feature:

  • Only IPv4 address family is supported for a default or a non-default VRF.

  • No T-LDP support in a VRF context.

  • An address family under VRF and VRF interface must be configured for non-default VRFs.

  • Following scenarios are not supported :

    • Different VRFs between a given PE-CE device pair (VRFs configured on different links and interfaces)

    • LDP/BGP CSC co-existence on a given VRF between a given PE-CE device pair:

      • Single link

      • Parallel links: LDP CSC on one link and BGP CSC on the other

  • LDP router-id must be configured per-VRF. If not configured for non-default VRF, LDP computes router-id from available loopback interfaces under the VRF.

  • It is recommended to configure a routable discovery transport address under a VRF IPv4 address-family submode for deterministic transport endpoint and connection.

  • When LDP CSC is configured and in use:

    • BGP label allocation policy for VRF prefixes must be per-prefix

    • Selective VRF Download (SVD) feature must be disabled

How to Implement MPLS LDP

A typical MPLS LDP deployment requires coordination among several global neighbor routers. Various configuration tasks are required to implement MPLS LDP :

Configuring LDP Discovery Parameters

Perform this task to configure LDP discovery parameters (which may be crucial for LDP operations).


Note


The LDP discovery mechanism is used to discover or locate neighbor nodes.


SUMMARY STEPS

    1.    configure

    2.    mpls ldp

    3.    [vrf vrf-name] router-id lsr-id

    4.    discovery { hello | targeted-hello } holdtime seconds

    5.    discovery { hello | targeted-hello } interval seconds

    6.    Use the commit or end command.

    7.    (Optional) show mpls ldp [vrf vrf-name] parameters


DETAILED STEPS
     Command or ActionPurpose
    Step 1 configure


    Example:
    RP/0/RP0/CPU0:router# configure
     

    Enters global configuration mode.

     
    Step 2 mpls ldp


    Example:
    RP/0/RP0/CPU0:router(config)# mpls ldp
    
     

    Enters MPLS LDP configuration mode.

     
    Step 3[vrf vrf-name] router-id lsr-id


    Example:
    RP/0/RP0/CPU0:router(config-ldp)# router-id 192.168.70.1
    
     

    (Optional) Specifies a non-default VRF.

    Specifies the router ID of the local node.

    • In Cisco IOS XR software, the router ID is specified as an interface IP address. By default, LDP uses the global router ID (configured by the global router ID process).

     
    Step 4 discovery { hello | targeted-hello } holdtime seconds


    Example:
    RP/0/RP0/CPU0:router(config-ldp)# discovery hello holdtime 30
      RP/0/RP0/CPU0:router(config-ldp)# discovery targeted-hello holdtime 180
      
     

    Specifies the time that a discovered neighbor is kept without receipt of any subsequent hello messages. The default value for the seconds argument is 15 seconds for link hello and 90 seconds for targeted hello messages.

     
    Step 5 discovery { hello | targeted-hello } interval seconds


    Example:
    RP/0/RP0/CPU0:router(config-ldp)# discovery hello interval 15 
      RP/0/RP0/CPU0:router(config-ldp)# discovery targeted-hello interval 20
      
     

    Selects the period of time between the transmission of consecutive hello messages. The default value for the seconds argument is 5 seconds for link hello messages and 10 seconds for targeted hello messages.

     
    Step 6 Use the commit or end command.  

    commit—Saves the configuration changes and remains within the configuration session.

    end—Prompts user to take one of these actions:
    • Yes— Saves configuration changes and exits the configuration session.

    • No—Exits the configuration session without committing the configuration changes.

    • Cancel—Remains in the configuration session, without committing the configuration changes.

     
    Step 7 show mpls ldp [vrf vrf-name] parameters


    Example:
    
    RP/0/RP0/CPU0:router
    show mpls ldp parameters
    
    
    
    RP/0/RP0/CPU0:router
    show mpls ldp vrf red parameters
    
     
    (Optional)

    Displays all the current MPLS LDP parameters.

    Displays the LDP parameters for the specified VRF.

     
    Related Concepts

    Configuring LDP Discovery Over a Link

    Perform this task to configure LDP discovery over a link.


    Note


    There is no need to enable LDP globally.


    Before You Begin

    A stable router ID is required at either end of the link to ensure the link discovery (and session setup) is successful. If you do not assign a router ID to the routers, the system will default to the global router ID. Default router IDs are subject to change and may cause an unstable discovery.

    SUMMARY STEPS

      1.    configure

      2.    mpls ldp

      3.    [vrf vrf-name] router-id lsr-id

      4.    interface type interface-path-id

      5.    Use the commit or end command.

      6.    (Optional) show mpls ldp discovery

      7.    (Optional) show mpls ldp vrf vrf-name discovery

      8.    (Optional) show mpls ldp vrf all discovery summary

      9.    (Optional) show mpls ldp vrf all discovery brief

      10.    (Optional) show mpls ldp vrf all ipv4 discovery summary

      11.    (Optional) show mpls ldp discovery summary all


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 configure


      Example:
      RP/0/RP0/CPU0:router# configure
       

      Enters global configuration mode.

       
      Step 2 mpls ldp


      Example:
      RP/0/RP0/CPU0:router(config)# mpls ldp
      
       

      Enters MPLS LDP configuration mode.

       
      Step 3[vrf vrf-name] router-id lsr-id


      Example:
      RP/0/RP0/CPU0:router(config-ldp)# router-id 192.168.70.1
      
       

      (Optional) Specifies a non-default VRF.

      Specifies the router ID of the local node.

      • In Cisco IOS XR software, the router ID is specified as an interface name or IP address. By default, LDP uses the global router ID (configured by the global router ID process).

       
      Step 4 interface type interface-path-id


      Example:
      RP/0/RP0/CPU0:router(config-ldp)# interface tunnel-te 12001
      RP/0/RP0/CPU0:router(config-ldp-if)#
      
       

      Enters interface configuration mode for the LDP protocol. Interface type must be Tunnel-TE.

       
      Step 5 Use the commit or end command.  

      commit—Saves the configuration changes and remains within the configuration session.

      end—Prompts user to take one of these actions:
      • Yes— Saves configuration changes and exits the configuration session.

      • No—Exits the configuration session without committing the configuration changes.

      • Cancel—Remains in the configuration session, without committing the configuration changes.

       
      Step 6 show mpls ldp discovery


      Example:
      RP/0/RP0/CPU0:routershow mpls ldp discovery
      
       
      (Optional)

      Displays the status of the LDP discovery process. This command, without an interface filter, generates a list of interfaces over which the LDP discovery process is running. The output information contains the state of the link (xmt/rcv hellos), local LDP identifier, the discovered peer’s LDP identifier, and holdtime values.

       
      Step 7show mpls ldp vrf vrf-name discovery


      Example:
      RP/0/RP0/CPU0:routershow mpls ldp vrf red discovery
      
       
      (Optional)

      Displays the status of the LDP discovery process for the specified VRF.

       
      Step 8show mpls ldp vrf all discovery summary


      Example:
      RP/0/RP0/CPU0:routershow mpls ldp vrf all discovery summary
      
       
      (Optional)

      Displays the summarized status of the LDP discovery process for all VRFs.

       
      Step 9show mpls ldp vrf all discovery brief


      Example:
      RP/0/RP0/CPU0:routershow mpls ldp vrf all discovery brief
      
       
      (Optional)

      Displays the brief status of the LDP discovery process for all VRFs.

       
      Step 10show mpls ldp vrf all ipv4 discovery summary


      Example:
      RP/0/RP0/CPU0:routershow mpls ldp vrf all ipv4 discovery summary
      
       
      (Optional)

      Displays the summarized status of the LDP discovery process for all VRFs for the IPv4 address family.

       
      Step 11show mpls ldp discovery summary all


      Example:
      RP/0/RP0/CPU0:routershow mpls ldp discovery summary all
      
       
      (Optional)

      Displays the aggregate summary across all the LDP discovery processes.

       
      Related Concepts
      Related References

      Configuring LDP Discovery for Active Targeted Hellos

      Perform this task to configure LDP discovery for active targeted hellos.


      Note


      The active side for targeted hellos initiates the unicast hello toward a specific destination.


      Before You Begin

      These prerequisites are required to configure LDP discovery for active targeted hellos:

      • Stable router ID is required at either end of the targeted session. If you do not assign a router ID to the routers, the system will default to the global router ID. Please note that default router IDs are subject to change and may cause an unstable discovery.

      • One or more MPLS Traffic Engineering tunnels are established between non-directly connected LSRs.

      SUMMARY STEPS

        1.    configure

        2.    mpls ldp

        3.    [vrf vrf-name] router-id lsr-id

        4.    interface type interface-path-id

        5.    Use the commit or end command.

        6.    (Optional) show mpls ldp discovery

        7.    (Optional) show mpls ldp vrf vrf-name discovery

        8.    (Optional) show mpls ldp vrf all discovery summary

        9.    (Optional) show mpls ldp vrf all discovery brief

        10.    (Optional) show mpls ldp vrf all ipv4 discovery summary

        11.    (Optional) show mpls ldp discovery summary all


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 configure


        Example:
        RP/0/RP0/CPU0:router# configure
         

        Enters global configuration mode.

         
        Step 2 mpls ldp


        Example:
        RP/0/RP0/CPU0:router(config)# mpls ldp
        
         

        Enters MPLS LDP configuration mode.

         
        Step 3[vrf vrf-name] router-id lsr-id


        Example:
        RP/0/RP0/CPU0:router(config-ldp)# router-id 192.168.70.1
        
         

        (Optional) Specifies a non-default VRF.

        Specifies the router ID of the local node.

        In Cisco IOS XR software, the router ID is specified as an interface name or IP address or LSR ID. By default, LDP uses the global router ID (configured by global router ID process).

         
        Step 4 interface type interface-path-id


        Example:
        RP/0/RP0/CPU0:router(config-ldp)# interface tunnel-te 12001
        
         

        Enters interface configuration mode for the LDP protocol.

         
        Step 5 Use the commit or end command.  

        commit—Saves the configuration changes and remains within the configuration session.

        end—Prompts user to take one of these actions:
        • Yes— Saves configuration changes and exits the configuration session.

        • No—Exits the configuration session without committing the configuration changes.

        • Cancel—Remains in the configuration session, without committing the configuration changes.

         
        Step 6 show mpls ldp discovery


        Example:
        RP/0/RP0/CPU0:routershow mpls ldp discovery
        
         
        (Optional)

        Displays the status of the LDP discovery process. This command, without an interface filter, generates a list of interfaces over which the LDP discovery process is running. The output information contains the state of the link (xmt/rcv hellos), local LDP identifier, the discovered peer’s LDP identifier, and holdtime values.

         
        Step 7show mpls ldp vrf vrf-name discovery


        Example:
        RP/0/RP0/CPU0:routershow mpls ldp vrf red discovery
        
         
        (Optional)

        Displays the status of the LDP discovery process for the specified VRF.

         
        Step 8show mpls ldp vrf all discovery summary


        Example:
        RP/0/RP0/CPU0:routershow mpls ldp vrf all discovery summary
        
         
        (Optional)

        Displays the summarized status of the LDP discovery process for all VRFs.

         
        Step 9show mpls ldp vrf all discovery brief


        Example:
        RP/0/RP0/CPU0:routershow mpls ldp vrf all discovery brief
        
         
        (Optional)

        Displays the brief status of the LDP discovery process for all VRFs.

         
        Step 10show mpls ldp vrf all ipv4 discovery summary


        Example:
        RP/0/RP0/CPU0:routershow mpls ldp vrf all ipv4 discovery summary
        
         
        (Optional)

        Displays the summarized status of the LDP discovery process for all VRFs for the IPv4 address family.

         
        Step 11show mpls ldp discovery summary all


        Example:
        RP/0/RP0/CPU0:routershow mpls ldp discovery summary all
        
         
        (Optional)

        Displays the aggregate summary across all the LDP discovery processes.

         
        Related Concepts

        Configuring LDP Discovery for Passive Targeted Hellos

        Perform this task to configure LDP discovery for passive targeted hellos.

        A passive side for targeted hello is the destination router (tunnel tail), which passively waits for an incoming hello message. Because targeted hellos are unicast, the passive side waits for an incoming hello message to respond with hello toward its discovered neighbor.

        Before You Begin

        Stable router ID is required at either end of the link to ensure that the link discovery (and session setup) is successful. If you do not assign a router ID to the routers, the system defaults to the global router ID. Default router IDs are subject to change and may cause an unstable discovery.

        SUMMARY STEPS

          1.    configure

          2.    mpls ldp

          3.    [vrf vrf-name] router-id lsr-id

          4.    discovery targeted-hello accept

          5.    Use the commit or end command.

          6.    (Optional) show mpls ldp discovery

          7.    (Optional) show mpls ldp vrf vrf-name discovery

          8.    (Optional) show mpls ldp vrf all discovery summary

          9.    (Optional) show mpls ldp vrf all discovery brief

          10.    (Optional) show mpls ldp vrf all ipv4 discovery summary

          11.    (Optional) show mpls ldp discovery summary all


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 configure


          Example:
          RP/0/RP0/CPU0:router# configure
           

          Enters global configuration mode.

           
          Step 2 mpls ldp


          Example:
          RP/0/RP0/CPU0:router(config)# mpls ldp
          
           

          Enters MPLS LDP configuration mode.

           
          Step 3[vrf vrf-name] router-id lsr-id


          Example:
          RP/0/RP0/CPU0:router(config-ldp)# router-id 192.168.70.1
          
           

          (Optional) Specifies a non-default VRF.

          Specifies the router ID of the local node.

          • In Cisco IOS XR software, the router ID is specified as an interface IP address or LSR ID. By default, LDP uses the global router ID (configured by global router ID process).

           
          Step 4 discovery targeted-hello accept


          Example:
          RP/0/RP0/CPU0:router(config-ldp)# discovery targeted-hello accept
          
           

          Directs the system to accept targeted hello messages from any source and activates passive mode on the LSR for targeted hello acceptance.

          • This command is executed on the receiver node (with respect to a given MPLS TE tunnel).

          • You can control the targeted-hello acceptance using the discovery targeted-hello accept command.

           
          Step 5 Use the commit or end command.  

          commit—Saves the configuration changes and remains within the configuration session.

          end—Prompts user to take one of these actions:
          • Yes— Saves configuration changes and exits the configuration session.

          • No—Exits the configuration session without committing the configuration changes.

          • Cancel—Remains in the configuration session, without committing the configuration changes.

           
          Step 6 show mpls ldp discovery


          Example:
          RP/0/RP0/CPU0:routershow mpls ldp discovery
          
           
          (Optional)

          Displays the status of the LDP discovery process. This command, without an interface filter, generates a list of interfaces over which the LDP discovery process is running. The output information contains the state of the link (xmt/rcv hellos), local LDP identifier, the discovered peer’s LDP identifier, and holdtime values.

           
          Step 7show mpls ldp vrf vrf-name discovery


          Example:
          RP/0/RP0/CPU0:routershow mpls ldp vrf red discovery
          
           
          (Optional)

          Displays the status of the LDP discovery process for the specified VRF.

           
          Step 8show mpls ldp vrf all discovery summary


          Example:
          RP/0/RP0/CPU0:routershow mpls ldp vrf all discovery summary
          
           
          (Optional)

          Displays the summarized status of the LDP discovery process for all VRFs.

           
          Step 9show mpls ldp vrf all discovery brief


          Example:
          RP/0/RP0/CPU0:routershow mpls ldp vrf all discovery brief
          
           
          (Optional)

          Displays the brief status of the LDP discovery process for all VRFs.

           
          Step 10show mpls ldp vrf all ipv4 discovery summary


          Example:
          RP/0/RP0/CPU0:routershow mpls ldp vrf all ipv4 discovery summary
          
           
          (Optional)

          Displays the summarized status of the LDP discovery process for all VRFs for the IPv4 address family.

           
          Step 11show mpls ldp discovery summary all


          Example:
          RP/0/RP0/CPU0:routershow mpls ldp discovery summary all
          
           
          (Optional)

          Displays the aggregate summary across all the LDP discovery processes.

           
          Related Concepts

          Configuring Label Advertisement Control (Outbound Filtering)

          Perform this task to configure label advertisement (outbound filtering).

          By default, a label switched router (LSR) advertises all incoming label prefixes to each neighboring router. You can control the exchange of label binding information using the mpls ldp label advertise command. Using the optional keywords, you can advertise selective prefixes to all neighbors, advertise selective prefixes to defined neighbors, or disable label advertisement to all peers for all prefixes.


          Note


          Prefixes and peers advertised selectively are defined in the access list.


          Before You Begin

          Before configuring label advertisement, enable LDP and configure an access list.

          SUMMARY STEPS

            1.    configure

            2.    mpls ldp

            3.    [vrf vrf-name] address-family { ipv4}

            4.    label local advertise [ to ldp-id for prefix-acl | interface type interface-path-id ]

            5.    Use the commit or end command.


          DETAILED STEPS
             Command or ActionPurpose
            Step 1 configure


            Example:
            RP/0/RP0/CPU0:router# configure
             

            Enters global configuration mode.

             
            Step 2 mpls ldp


            Example:
            RP/0/RP0/CPU0:router(config)# mpls ldp
            
             

            Enters MPLS LDP configuration mode.

             
            Step 3[vrf vrf-name] address-family { ipv4}


            Example:
            RP/0/RP0/CPU0:router(config-ldp)# address-family ipv4
            
            
             

            (Optional) Specifies a non-default VRF.

            Enables the LDP IPv4 address family.

             
            Step 4label local advertise [ to ldp-id for prefix-acl | interface type interface-path-id ]

            Example:
            RP/0/RP0/CPU0:router(config-ldp-af)# label local advertise to 1.1.1.1:0 for pfx_acl1
            
            
            RP/0/RP0/CPU0:router(config-ldp-af)# label local advertise interface POS 0/1/0/0
             
            Configures outbound label advertisement control by specifying one of the following options:
            interface

            Specifies an interface for label advertisement.

            to ldp-id
            for prefix-acl

            Specifies neighbors to advertise and receive label advertisements.

             
            Step 5 Use the commit or end command.  

            commit—Saves the configuration changes and remains within the configuration session.

            end—Prompts user to take one of these actions:
            • Yes— Saves configuration changes and exits the configuration session.

            • No—Exits the configuration session without committing the configuration changes.

            • Cancel—Remains in the configuration session, without committing the configuration changes.

             

            Setting Up LDP Neighbors

            Perform this task to set up LDP neighbors.

            Before You Begin

            Stable router ID is required at either end of the link to ensure the link discovery (and session setup) is successful. If you do not assign a router ID to the routers, the system will default to the global router ID. Default router IDs are subject to change and may cause an unstable discovery.

            SUMMARY STEPS

              1.    configure

              2.    mpls ldp

              3.    interface type interface-path-id

              4.    address-family {ipv4 }

              5.    discovery transport-address [ ip-address | interface ]

              6.    exit

              7.    holdtime seconds

              8.    [vrf vrf-name] neighbor ldp-id password [ encrypted ] password

              9.    backoff initial maximum

              10.    Use the commit or end command.

              11.    (Optional) show mpls ldp neighbor

              12.    (Optional) show mpls ldp vrf vrf-name neighbor

              13.    (Optional) show mpls ldp vrf all neighbor brief

              14.    (Optional) clear mpls ldp neighbor

              15.    (Optional) clear mpls ldp vrf all neighbor

              16.    (Optional) clear mpls ldp vrf vrf-name neighbor


            DETAILED STEPS
               Command or ActionPurpose
              Step 1 configure


              Example:
              RP/0/RP0/CPU0:router# configure
               

              Enters global configuration mode.

               
              Step 2 mpls ldp


              Example:
              RP/0/RP0/CPU0:router(config)# mpls ldp
              
               

              Enters MPLS LDP configuration mode.

               
              Step 3 interface type interface-path-id


              Example:
              RP/0/RP0/CPU0:router(config-ldp)# interface POS 0/1/0/0
              
               

              Enters interface configuration mode for the LDP protocol.

               
              Step 4 address-family {ipv4 }


              Example:
              RP/0/RP0/CPU0:router(config-ldp-if)# address-family ipv4
              

              or

               

              Enables the LDP IPv4 address family.

               
              Step 5 discovery transport-address [ ip-address | interface ]


              Example:
              RP/0/RP0/CPU0:router(config-ldp-if-af)# discovery transport-address 192.168.1.42
              

              or

              RP/0/RP0/CPU0:router(config-ldp-if-af)# discovery transport-address interface
              
               

              Provides an alternative transport address for a TCP connection.

              • Default transport address advertised by an LSR (for TCP connections) to its peer is the router ID.

              • Transport address configuration is applied for a given LDP-enabled interface.

              • If the interface version of the command is used, the configured IP address of the interface is passed to its neighbors as the transport address.

               
              Step 6 exit


              Example:
              RP/0/RP0/CPU0:router(config-ldp-if)# exit
              
               

              Exits the current configuration mode.

               
              Step 7 holdtime seconds


              Example:
              RP/0/RP0/CPU0:router(config-ldp)# holdtime 30
              
               

              Changes the time for which an LDP session is maintained in the absence of LDP messages from the peer.

              • Outgoing keepalive interval is adjusted accordingly (to make three keepalives in a given holdtime) with a change in session holdtime value.

              • Session holdtime is also exchanged when the session is established.

              • In this example holdtime is set to 30 seconds, which causes the peer session to timeout in 30 seconds, as well as transmitting outgoing keepalive messages toward the peer every 10 seconds.

               
              Step 8 [vrf vrf-name] neighbor ldp-id password [ encrypted ] password


              Example:
              RP/0/RP0/CPU0:router(config-ldp)# neighbor 192.168.2.44:0 password secretpasswd
              
               

              (Optional) Specifies a non-default VRF.

              Configures password authentication (using the TCP MD5 option) for a given neighbor.

               
              Step 9 backoff initial maximum


              Example:
              RP/0/RP0/CPU0:router(config-ldp)# backoff 10 20
              
               

              Configures the parameters for the LDP backoff mechanism. The LDP backoff mechanism prevents two incompatibly configured LSRs from engaging in an unthrottled sequence of session setup failures. If a session setup attempt fails due to such incompatibility, each LSR delays its next attempt (backs off), increasing the delay exponentially with each successive failure until the maximum backoff delay is reached.

               
              Step 10 Use the commit or end command.  

              commit—Saves the configuration changes and remains within the configuration session.

              end—Prompts user to take one of these actions:
              • Yes— Saves configuration changes and exits the configuration session.

              • No—Exits the configuration session without committing the configuration changes.

              • Cancel—Remains in the configuration session, without committing the configuration changes.

               
              Step 11 show mpls ldp neighbor


              Example:
              RP/0/RP0/CPU0:routershow mpls ldp neighbor
              
               
              (Optional)

              Displays the status of the LDP session with its neighbors. This command can be run with various filters as well as with the brief option.

               
              Step 12show mpls ldp vrf vrf-name neighbor


              Example:
              RP/0/RP0/CPU0:routershow mpls ldp vrf red neighbor
              
               
              (Optional)

              Displays the status of the LDP session with its neighbors for the specified VRF. This command can be run with the brief option.

               
              Step 13show mpls ldp vrf all neighbor brief


              Example:
              RP/0/RP0/CPU0:routershow mpls ldp vrf all neighbor brief
              
               
              (Optional)

              Displays the brief LDP session neighbor information for all VRFs.

               
              Step 14clear mpls ldp neighbor


              Example:
              RP/0/RP0/CPU0:routerclear mpls ldp neighbor 
              
               
              (Optional)

              Resets an LDP session.

               
              Step 15clear mpls ldp vrf all neighbor


              Example:
              RP/0/RP0/CPU0:routerclear mpls ldp vrf all neighbor 
              
               
              (Optional)

              Resets LDP session for all VRFs.

               
              Step 16clear mpls ldp vrf vrf-name neighbor


              Example:
              RP/0/RP0/CPU0:routerclear mpls ldp vrf red neighbor 
              
               
              (Optional)

              Resets LDP session for the specified VRF.

               

              Setting Up LDP Forwarding

              Perform this task to set up LDP forwarding.

              By default, the LDP control plane implements the penultimate hop popping (PHOP) mechanism. The PHOP mechanism requires that label switched routers use the implicit-null label as a local label for the given Forwarding Equivalence Class (FEC) for which LSR is the penultimate hop. Although PHOP has certain advantages, it may be required to extend LSP up to the ultimate hop under certain circumstances (for example, to propagate MPL QoS). This is done using a special local label (explicit-null) advertised to the peers after which the peers use this label when forwarding traffic toward the ultimate hop (egress LSR).

              Before You Begin

              Stable router ID is required at either end of the link to ensure the link discovery (and session setup) is successful. If you do not assign a router ID to the routers, the system will default to the global router ID. Default router IDs are subject to change and may cause an unstable discovery.

              SUMMARY STEPS

                1.    configure

                2.    mpls ldp

                3.    [vrf vrf-name] address-family {ipv4 }

                4.    label local advertise explicit-null

                5.    Use the commit or end command.

                6.    (Optional) show mpls ldp forwarding

                7.    (Optional) show mpls ldp vrf all forwarding

                8.    (Optional) show mpls ldp vrf all forwarding summary

                9.    (Optional) show mpls ldp vrf vrf-name ipv4 forwarding

                10.    (Optional) show mpls ldp forwarding summary all

                11.    (Optional) clear mpls ldp vrf vrf-name ipv4 forwarding

                12.    (Optional) show mpls forwarding

                13.    (Optional) ping ip-address


              DETAILED STEPS
                 Command or ActionPurpose
                Step 1 configure


                Example:
                RP/0/RP0/CPU0:router# configure
                 

                Enters global configuration mode.

                 
                Step 2 mpls ldp


                Example:
                RP/0/RP0/CPU0:router(config)# mpls ldp
                
                 

                Enters MPLS LDP configuration mode.

                 
                Step 3 [vrf vrf-name] address-family {ipv4 }


                Example:
                RP/0/RP0/CPU0:router(config-ldp)# address-family ipv4
                

                or

                 

                (Optional) Specifies a non-default VRF.

                Enables the LDP IPv4 address family.

                 
                Step 4 label local advertise explicit-null


                Example:
                RP/0/RP0/CPU0:router(config-ldp-af)# label local advertise explicit-null
                
                 

                Causes a router to advertise an explicit null label in situations where it normally advertises an implicit null label (for example, to enable an ultimate-hop disposition instead of PHOP).

                 
                Step 5 Use the commit or end command.  

                commit—Saves the configuration changes and remains within the configuration session.

                end—Prompts user to take one of these actions:
                • Yes— Saves configuration changes and exits the configuration session.

                • No—Exits the configuration session without committing the configuration changes.

                • Cancel—Remains in the configuration session, without committing the configuration changes.

                 
                Step 6 show mpls ldp forwarding


                Example:
                RP/0/RP0/CPU0:routershow mpls ldp forwarding
                
                 
                (Optional)

                Displays the MPLS LDP view of installed forwarding states (rewrites).

                 
                Step 7show mpls ldp vrf all forwarding


                Example:
                RP/0/RP0/CPU0:routershow mpls ldp vrf all forwarding
                
                 
                (Optional)

                Displays the forwarding setup information of all LDP configured VRFs.

                 
                Step 8show mpls ldp vrf all forwarding summary


                Example:
                RP/0/RP0/CPU0:routershow mpls ldp vrf all forwarding summary
                
                 
                (Optional)

                Displays the forwarding setup summary of all LDP configured VRFs.

                 
                Step 9show mpls ldp vrf vrf-name ipv4 forwarding


                Example:
                RP/0/RP0/CPU0:routershow mpls ldp vrf red ipv4 forwarding
                
                 
                (Optional)

                Displays the forwarding setup information for the specified VRF for IPv4.

                 
                Step 10show mpls ldp forwarding summary all


                Example:
                RP/0/RP0/CPU0:routershow mpls ldp forwarding summary all
                
                 
                (Optional)

                Displays the aggregate summary across LDP processes and all VRFs.

                 
                Step 11clear mpls ldp vrf vrf-name ipv4 forwarding


                Example:
                RP/0/RP0/CPU0:routerclear mpls ldp vrf red ipv4 forwarding
                
                 
                (Optional)

                Resets the MPLS forwarding rewrites for the specified VRF for IPv4.

                 
                Step 12 show mpls forwarding


                Example:
                RP/0/RP0/CPU0:routershow mpls forwarding
                
                 
                (Optional)

                Displays a global view of all MPLS installed forwarding states (rewrites) by various applications (LDP, TE, and static).

                 
                Step 13 ping ip-address


                Example:
                RP/0/RP0/CPU0:routerping 192.168.2.55
                
                 
                (Optional)

                Checks for connectivity to a particular IP address (going through MPLS LSP as shown in the show mpls forwarding command).

                 
                Related Concepts

                Configuring Global Transport Address

                Perform this task to configure global transport address for the IPv4 address family.

                SUMMARY STEPS

                  1.    configure

                  2.    mpls ldp

                  3.    address-family ipv4

                  4.    discovery transport-address ip-address

                  5.    end or commit


                DETAILED STEPS
                   Command or ActionPurpose
                  Step 1 configure


                  Example:
                  RP/0/RP0/CPU0:router# configure
                   

                  Enters global configuration mode.

                   
                  Step 2 mpls ldp


                  Example:
                  RP/0/RP0/CPU0:router(config)# mpls ldp
                  
                   

                  Enters MPLS LDP configuration mode.

                   
                  Step 3address-family ipv4


                  Example:
                  RP/0/RP0/CPU0:router(config-ldp)# address-family ipv4
                  
                  
                   

                  Enables LDP IPv4 address family.

                   
                  Step 4 discovery transport-address ip-address


                  Example:
                  RP/0/RP0/CPU0:router(config-ldp-af)# discovery transport-address 192.168.1.42
                  
                   

                  Provides an alternative transport address for a TCP connection.

                  • Default transport address advertised by an LSR (for TCP connections) to its peer is the router ID.

                   
                  Step 5end or commit

                  Example:
                  
                  RP/0/RP/0/RP0/CPU0:router (config-ldp-af)# end
                  

                  or

                  RP/0/RP/0/RP0/CPU0:router (config-ldp-af)# commit
                  
                   
                  • When you issue the end command, the system prompts you to commit changes:

                    
                    Uncommitted changes found, commit them before
                    exiting(yes/no/cancel)?
                    [cancel]:
                    
                  • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

                  • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

                  • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

                  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

                   

                  Setting Up LDP NSF Using Graceful Restart

                  Perform this task to set up NSF using LDP graceful restart.

                  LDP graceful restart is a way to enable NSF for LDP. The correct way to set up NSF using LDP graceful restart is to bring up LDP neighbors (link or targeted) with additional configuration related to graceful restart.

                  Before You Begin

                  Stable router ID is required at either end of the link to ensure the link discovery (and session setup) is successful. If you do not assign a router ID to the routers, the system will default to the global router ID. Default router IDs are subject to change and may cause an unstable discovery.

                  SUMMARY STEPS

                    1.    configure

                    2.    mpls ldp

                    3.    interface type interface-path-id

                    4.    exit

                    5.    graceful-restart

                    6.    graceful-restart forwarding-state-holdtime seconds

                    7.    graceful-restart reconnect-timeout seconds

                    8.    Use the commit or end command.

                    9.    (Optional) show mpls ldp [vrf vrf-name] parameters

                    10.    (Optional) show mpls ldp neighbor

                    11.    (Optional) show mpls ldp graceful-restart

                    12.    (Optional) show mpls ldp vrf all graceful-restart

                    13.    (Optional) show mpls ldp vrf vrf-name graceful-restart


                  DETAILED STEPS
                     Command or ActionPurpose
                    Step 1 configure


                    Example:
                    RP/0/RP0/CPU0:router# configure
                     

                    Enters global configuration mode.

                     
                    Step 2 mpls ldp


                    Example:
                    RP/0/RP0/CPU0:router(config)# mpls ldp
                    
                     

                    Enters MPLS LDP configuration mode.

                     
                    Step 3 interface type interface-path-id


                    Example:
                    RP/0/RP0/CPU0:router(config-ldp)# interface POS 0/1/0/0
                    RP/0/RP0/CPU0:router(config-ldp-if)# 
                    
                     

                    Enters interface configuration mode for the LDP protocol.

                     
                    Step 4 exit


                    Example:
                    RP/0/RP0/CPU0:router(config-ldp-if)# exit
                    
                     

                    Exits the current configuration mode.

                     
                    Step 5 graceful-restart


                    Example:
                    RP/0/RP0/CPU0:router(config-ldp)# graceful-restart
                    
                     

                    Enables the LDP graceful restart feature.

                     
                    Step 6 graceful-restart forwarding-state-holdtime seconds


                    Example:
                    RP/0/RP0/CPU0:router(config-ldp)# graceful-restart forwarding-state-holdtime 180
                    
                     

                    Specifies the length of time that forwarding can keep LDP-installed forwarding states and rewrites, and specifies wh en the LDP control plane restarts.

                    • After restart of the control plane, when the forwarding state holdtime expires, any previously installed LDP forwarding state or rewrite that is not yet refreshed is deleted from the forwarding.

                    • Recovery time sent after restart is computed as the current remaining value of the forwarding state hold timer.

                     
                    Step 7 graceful-restart reconnect-timeout seconds


                    Example:
                    RP/0/RP0/CPU0:router(config-ldp)# graceful-restart reconnect-timeout 169
                    
                     

                    Specifies the length of time a neighbor waits before restarting the node to reconnect before declaring an earlier graceful restart session as down. This command is used to start a timer on the peer (upon a neighbor restart). This timer is referred to as Neighbor Liveness timer.

                     
                    Step 8 Use the commit or end command.  

                    commit—Saves the configuration changes and remains within the configuration session.

                    end—Prompts user to take one of these actions:
                    • Yes— Saves configuration changes and exits the configuration session.

                    • No—Exits the configuration session without committing the configuration changes.

                    • Cancel—Remains in the configuration session, without committing the configuration changes.

                     
                    Step 9 show mpls ldp [vrf vrf-name] parameters


                    Example:
                    
                    RP/0/RP0/CPU0:router
                    show mpls ldp parameters
                    
                    
                    
                    RP/0/RP0/CPU0:router
                    show mpls ldp vrf red parameters
                    
                     
                    (Optional)

                    Displays all the current MPLS LDP parameters.

                    Displays the LDP parameters for the specified VRF.

                     
                    Step 10 show mpls ldp neighbor


                    Example:
                    RP/0/RP0/CPU0:routershow mpls ldp neighbor
                    
                     
                    (Optional)

                    Displays the status of the LDP session with its neighbors. This command can be run with various filters as well as with the brief option.

                     
                    Step 11 show mpls ldp graceful-restart


                    Example:
                    RP/0/RP0/CPU0:routershow mpls ldp graceful-restart
                    
                     
                    (Optional)

                    Displays the status of the LDP graceful restart feature. The output of this command not only shows states of different graceful restart timers, but also a list of graceful restart neighbors, their state, and reconnect count.

                     
                    Step 12show mpls ldp vrf all graceful-restart


                    Example:
                    RP/0/RP0/CPU0:routershow mpls ldp vrf all graceful-restart
                    
                     
                    (Optional)

                    Displays the status of the LDP graceful restart for all VRFs.

                     
                    Step 13show mpls ldp vrf vrf-name graceful-restart


                    Example:
                    RP/0/RP0/CPU0:routershow mpls ldp vrf red graceful-restart
                    
                     
                    (Optional)

                    Displays the status of the LDP graceful restart for the specified VRF.

                     

                    Configuring Label Acceptance Control (Inbound Filtering)

                    Perform this task to configure LDP inbound label filtering.


                    Note


                    By default, there is no inbound label filtering performed by LDP and thus an LSR accepts (and retains) all remote label bindings from all peers.


                    SUMMARY STEPS

                      1.    configure

                      2.    mpls ldp

                      3.    [vrf vrf-name] address-family { ipv4}

                      4.    label remote accept from ldp-id for prefix-acl

                      5.    Use the commit or end command.


                    DETAILED STEPS
                       Command or ActionPurpose
                      Step 1 configure


                      Example:
                      RP/0/RP0/CPU0:router# configure
                       

                      Enters global configuration mode.

                       
                      Step 2 mpls ldp


                      Example:
                      RP/0/RP0/CPU0:router(config)# mpls ldp
                      
                       

                      Enters the MPLS LDP configuration mode.

                       
                      Step 3[vrf vrf-name] address-family { ipv4}


                      Example:
                      RP/0/RP0/CPU0:router(config-ldp)# address-family ipv4
                      
                      
                       

                      (Optional) Specifies a non-default VRF.

                      Enables the LDP IPv4 address family.

                       
                      Step 4label remote accept from ldp-id for prefix-acl


                      Example:
                      RP/0/RP0/CPU0:router(config-ldp-af)# label remote accept from 192.168.1.1:0 for pfx_acl_1
                      
                      
                       

                      Configures inbound label acceptance control for prefixes specified by prefix-acl from neighbor (as specified by its LDP ID).

                       
                      Step 5 Use the commit or end command.  

                      commit—Saves the configuration changes and remains within the configuration session.

                      end—Prompts user to take one of these actions:
                      • Yes— Saves configuration changes and exits the configuration session.

                      • No—Exits the configuration session without committing the configuration changes.

                      • Cancel—Remains in the configuration session, without committing the configuration changes.

                       

                      Configuring Local Label Allocation Control

                      Perform this task to configure label allocation control.


                      Note


                      By default, local label allocation control is disabled and all non-BGP prefixes are assigned local labels.


                      SUMMARY STEPS

                        1.    configure

                        2.    mpls ldp

                        3.    [vrf vrf-name] address-family { ipv4}

                        4.    label local allocate for prefix-acl

                        5.    Use the commit or end command.


                      DETAILED STEPS
                         Command or ActionPurpose
                        Step 1 configure


                        Example:
                        RP/0/RP0/CPU0:router# configure
                         

                        Enters global configuration mode.

                         
                        Step 2 mpls ldp


                        Example:
                        RP/0/RP0/CPU0:router(config)# mpls ldp
                        
                         

                        Enters the MPLS LDP configuration mode.

                         
                        Step 3[vrf vrf-name] address-family { ipv4}


                        Example:
                        RP/0/RP0/CPU0:router(config-ldp)# address-family ipv4
                        
                        
                         

                        (Optional) Specifies a non-default VRF.

                        Enables the LDP IPv4 address family.

                         
                        Step 4label local allocate for prefix-acl


                        Example:
                        RP/0/RP0/CPU0:router(config-ldp-af)# label local allocate for pfx_acl_1
                        
                        
                         

                        Configures label allocation control for prefixes as specified by prefix-acl.

                         
                        Step 5 Use the commit or end command.  

                        commit—Saves the configuration changes and remains within the configuration session.

                        end—Prompts user to take one of these actions:
                        • Yes— Saves configuration changes and exits the configuration session.

                        • No—Exits the configuration session without committing the configuration changes.

                        • Cancel—Remains in the configuration session, without committing the configuration changes.

                         

                        Configuring Session Protection

                        Perform this task to configure LDP session protection.

                        By default, there is no protection is done for link sessions by means of targeted hellos.

                        SUMMARY STEPS

                          1.    configure

                          2.    mpls ldp

                          3.    session protection [ for peer-acl ] [ duration seconds ]

                          4.    Use the commit or end command.


                        DETAILED STEPS
                           Command or ActionPurpose
                          Step 1 configure


                          Example:
                          RP/0/RP0/CPU0:router# configure
                           

                          Enters global configuration mode.

                           
                          Step 2 mpls ldp


                          Example:
                          RP/0/RP0/CPU0:router(config)# mpls ldp
                          
                           

                          Enters the MPLS LDP configuration mode.

                           
                          Step 3 session protection [ for peer-acl ] [ duration seconds ]


                          Example:
                          RP/0/RP0/CPU0:router(config-ldp)# session protection for peer_acl_1 duration 60
                          
                           

                          Configures LDP session protection for peers specified by peer-acl with a maximum duration, in seconds.

                           
                          Step 4 Use the commit or end command.  

                          commit—Saves the configuration changes and remains within the configuration session.

                          end—Prompts user to take one of these actions:
                          • Yes— Saves configuration changes and exits the configuration session.

                          • No—Exits the configuration session without committing the configuration changes.

                          • Cancel—Remains in the configuration session, without committing the configuration changes.

                           
                          Related Concepts

                          Configuring LDP IGP Synchronization: OSPF

                          Perform this task to configure LDP IGP Synchronization under OSPF.


                          Note


                          By default, there is no synchronization between LDP and IGPs.


                          SUMMARY STEPS

                            1.    configure

                            2.    router ospf process-name

                            3.    (Optional) vrf vrf-name

                            4.    Use one of the following commands:

                            • mpls ldp sync
                            • area area-id mpls ldp sync
                            • area area-id interface name mpls ldp sync

                            5.    (Optional) Use one of the following commands:

                            • mpls ldp sync
                            • area area-id mpls ldp sync
                            • area area-id interface name mpls ldp sync

                            6.    Use the commit or end command.

                            7.    (Optional) show mpls ldp vrf vrf-name ipv4 igp sync

                            8.    (Optional) show mpls ldp vrf all ipv4 igp sync

                            9.    (Optional) show mpls ldp { ipv4 }igp sync


                          DETAILED STEPS
                             Command or ActionPurpose
                            Step 1 configure


                            Example:
                            RP/0/RP0/CPU0:router# configure
                             

                            Enters global configuration mode.

                             
                            Step 2 router ospf process-name


                            Example:
                            RP/0/RP0/CPU0:router(config)# router ospf 100
                            
                             

                            Identifies the OSPF routing process and enters OSPF configuration mode.

                             
                            Step 3vrf vrf-name


                            Example:
                            RP/0/RP0/CPU0:router(config-ospf)# vrf red
                            
                             
                            (Optional)

                            Specifies the non-default VRF.

                             
                            Step 4Use one of the following commands:
                            • mpls ldp sync
                            • area area-id mpls ldp sync
                            • area area-id interface name mpls ldp sync


                            Example:
                            RP/0/RP0/CPU0:router(config-ospf)# mpls ldp sync
                            
                             

                            Enables LDP IGP synchronization on an interface.

                             
                            Step 5Use one of the following commands:
                            • mpls ldp sync
                            • area area-id mpls ldp sync
                            • area area-id interface name mpls ldp sync


                            Example:
                            RP/0/RP0/CPU0:router(config-ospf-vrf)# mpls ldp sync
                            
                            
                            RP/0/RP0/CPU0:router(config-ospf-vrf)# area 1 mpls ldp sync
                            
                            
                            RP/0/RP0/CPU0:router(config-ospf-vrf)# area 1 interface POS 0/2/0/0 mpls ldp sync
                            
                            
                             
                            (Optional)

                            Enables LDP IGP synchronization on an interface for the specified VRF.

                             
                            Step 6 Use the commit or end command.  

                            commit—Saves the configuration changes and remains within the configuration session.

                            end—Prompts user to take one of these actions:
                            • Yes— Saves configuration changes and exits the configuration session.

                            • No—Exits the configuration session without committing the configuration changes.

                            • Cancel—Remains in the configuration session, without committing the configuration changes.

                             
                            Step 7show mpls ldp vrf vrf-name ipv4 igp sync


                            Example:
                            RP/0/RP0/CPU0:router# show mpls ldp vrf red ipv4 igp sync
                            
                             
                            (Optional)

                            Displays the LDP IGP synchronization information for the specified VRF for address family IPv4.

                             
                            Step 8show mpls ldp vrf all ipv4 igp sync


                            Example:
                            RP/0/RP0/CPU0:router# show mpls ldp vrf all ipv4 igp sync
                            
                             
                            (Optional)

                            Displays the LDP IGP synchronization information for all VRFs for address family IPv4.

                             
                            Step 9show mpls ldp { ipv4 }igp sync

                            Example:
                            RP/0/RP0/CPU0:routershow mpls ldp ipv4 igp sync
                            
                            
                             
                            (Optional)

                            Displays the LDP IGP synchronization information for IPv4 address families.

                             
                            Related Concepts

                            Disabling LDP IGP Synchronization: OSPF

                            Perform this task to disable LDP IGP Synchronization under OSPF.

                            You can disable LDP IGP synchronization on a per-interface basis. This lets LDP enable all IGP interfaces except those that are explicitly disabled.

                            SUMMARY STEPS

                              1.    configure

                              2.    router ospf process-name

                              3.    (Optional) vrf vrf-name

                              4.    Use one of the following commands:

                              • area area-id mpls ldp sync disable
                              • area area-id interface name mpls ldp sync disable

                              5.    (Optional) Use one of the following commands:

                              • area area-id mpls ldp sync disable
                              • area area-id interface name mpls ldp sync disable

                              6.    Use the commit or end command.


                            DETAILED STEPS
                               Command or ActionPurpose
                              Step 1 configure


                              Example:
                              RP/0/RP0/CPU0:router# configure
                               

                              Enters global configuration mode.

                               
                              Step 2 router ospf process-name


                              Example:
                              RP/0/RP0/CPU0:router(config)# router ospf 109
                              
                               

                              Identifies the OSPF routing process and enters OSPF configuration mode.

                               
                              Step 3vrf vrf-name


                              Example:
                              RP/0/RP0/CPU0:router(config-ospf)# vrf red
                              
                               
                              (Optional)

                              Specifies the non-default VRF.

                               
                              Step 4Use one of the following commands:
                              • area area-id mpls ldp sync disable
                              • area area-id interface name mpls ldp sync disable


                              Example:
                              RP/0/RP0/CPU0:router(config-ospf)# area 1 mpls ldp sync disable
                              
                              
                              RP/0/RP0/CPU0:router(config-ospf)# area 1 interface POS 0/2/0/0 mpls ldp sync disable
                              
                              
                               

                              Disables LDP IGP synchronization on an interface.

                               
                              Step 5Use one of the following commands:
                              • area area-id mpls ldp sync disable
                              • area area-id interface name mpls ldp sync disable


                              Example:
                              RP/0/RP0/CPU0:router(config-ospf-vrf)# area 1 mpls ldp sync disable
                              
                              
                              RP/0/RP0/CPU0:router(config-ospf-vrf)# area 1 interface POS 0/2/0/0 mpls ldp sync disable
                              
                              
                               
                              (Optional)

                              Disables LDP IGP synchronization on an interface for the specified VRF.

                               
                              Step 6 Use the commit or end command.  

                              commit—Saves the configuration changes and remains within the configuration session.

                              end—Prompts user to take one of these actions:
                              • Yes— Saves configuration changes and exits the configuration session.

                              • No—Exits the configuration session without committing the configuration changes.

                              • Cancel—Remains in the configuration session, without committing the configuration changes.

                               

                              Configuring LDP IGP Synchronization: ISIS

                              Perform this task to configure LDP IGP Synchronization under ISIS.


                              Note


                              By default, there is no synchronization between LDP and ISIS.


                              SUMMARY STEPS

                                1.    configure

                                2.    router isis instance-id

                                3.    interface type interface-path-id

                                4.    address-family {ipv4 } unicast

                                5.    mpls ldp sync

                                6.    Use the commit or end command.


                              DETAILED STEPS
                                 Command or ActionPurpose
                                Step 1 configure


                                Example:
                                RP/0/RP0/CPU0:router# configure
                                 

                                Enters global configuration mode.

                                 
                                Step 2 router isis instance-id


                                Example:
                                RP/0/RP0/CPU0:router(config)# router isis 100
                                RP/0/RP0/CPU0:router(config-isis)#
                                
                                 

                                Enables the Intermediate System-to-Intermediate System (IS-IS) routing protocol and defines an IS-IS instance.

                                 
                                Step 3 interface type interface-path-id


                                Example:
                                RP/0/RP0/CPU0:router(config-isis)# interface POS 0/2/0/0
                                RP/0/RP0/CPU0:router(config-isis-if)#
                                
                                 

                                Configures the IS-IS protocol on an interface and enters ISIS interface configuration mode.

                                 
                                Step 4 address-family {ipv4 } unicast


                                Example:
                                RP/0/RP0/CPU0:router(config-isis-if)# address-family ipv4 unicast
                                RP/0/RP0/CPU0:router(config-isis-if-af)#
                                
                                
                                 

                                Enters address family configuration mode for configuring IS-IS routing for a standard IP version 4 (IPv4) address prefix.

                                 
                                Step 5 mpls ldp sync


                                Example:
                                RP/0/RP0/CPU0:router(config-isis-if-af)# mpls ldp sync
                                
                                 

                                Enables LDP IGP synchronization.

                                 
                                Step 6 Use the commit or end command.  

                                commit—Saves the configuration changes and remains within the configuration session.

                                end—Prompts user to take one of these actions:
                                • Yes— Saves configuration changes and exits the configuration session.

                                • No—Exits the configuration session without committing the configuration changes.

                                • Cancel—Remains in the configuration session, without committing the configuration changes.

                                 
                                Related Concepts

                                Configuring LDP IGP Synchronization Delay Interval

                                Perform this task to configure the LDP IGP synchronization delay interval.

                                By default, LDP does not delay declaring sync up as soon as convergence conditions are met.

                                SUMMARY STEPS

                                  1.    configure

                                  2.    mpls ldp

                                  3.    igp sync delay delay-time

                                  4.    Use the commit or end command.


                                DETAILED STEPS
                                   Command or ActionPurpose
                                  Step 1 configure


                                  Example:
                                  RP/0/RP0/CPU0:router# configure
                                   

                                  Enters global configuration mode.

                                   
                                  Step 2 mpls ldp


                                  Example:
                                  RP/0/RP0/CPU0:router(config)# mpls ldp
                                  
                                   

                                  Enters the MPLS LDP configuration mode.

                                   
                                  Step 3 igp sync delay delay-time


                                  Example:
                                  RP/0/RP0/CPU0:router(config-ldp)# igp sync delay 30
                                  
                                   

                                  Configures LDP IGP synchronization delay in seconds.

                                   
                                  Step 4 Use the commit or end command.  

                                  commit—Saves the configuration changes and remains within the configuration session.

                                  end—Prompts user to take one of these actions:
                                  • Yes— Saves configuration changes and exits the configuration session.

                                  • No—Exits the configuration session without committing the configuration changes.

                                  • Cancel—Remains in the configuration session, without committing the configuration changes.

                                   
                                  Related Concepts

                                  Configuring LDP IGP Synchronization Process Restart Delay

                                  Perform this task to enable process restart delay when an LDP fails or restarts.


                                  Note


                                  By default, the LDP IGP Synchronization Process Restart Delay feature is disabled.


                                  SUMMARY STEPS

                                    1.    configure

                                    2.    mpls ldp

                                    3.    Use one of the following commands:

                                    • igp sync delay seconds
                                    • igp sync delay on-proc-restart delay-time

                                    4.    Use the commit or end command.


                                  DETAILED STEPS
                                     Command or ActionPurpose
                                    Step 1 configure


                                    Example:
                                    RP/0/RP0/CPU0:router# configure
                                     

                                    Enters global configuration mode.

                                     
                                    Step 2 mpls ldp


                                    Example:
                                    RP/0/RP0/CPU0:router(config)# mpls ldp
                                    
                                     

                                    Enters the MPLS LDP configuration mode.

                                     
                                    Step 3Use one of the following commands:
                                    • igp sync delay seconds
                                    • igp sync delay on-proc-restart delay-time


                                    Example:
                                    RP/0/RP0/CPU0:router(config-ldp)# igp sync delay 
                                     30
                                     

                                    Configures LDP IGP delay in seconds.

                                     
                                    Step 4 Use the commit or end command.  

                                    commit—Saves the configuration changes and remains within the configuration session.

                                    end—Prompts user to take one of these actions:
                                    • Yes— Saves configuration changes and exits the configuration session.

                                    • No—Exits the configuration session without committing the configuration changes.

                                    • Cancel—Remains in the configuration session, without committing the configuration changes.

                                     

                                    Enabling LDP Auto-Configuration for a Specified OSPF Instance

                                    Perform this task to enable IGP auto-configuration globally for a specified OSPF process name.

                                    You can disable auto-configuration on a per-interface basis. This lets LDP enable all IGP interfaces except those that are explicitly disabled.


                                    Note


                                    This feature is supported for IPv4 unicast family in default VRF only.


                                    SUMMARY STEPS

                                      1.    configure

                                      2.    router ospf process-name

                                      3.    mpls ldp auto-config

                                      4.    area area-id

                                      5.    interface type interface-path-id

                                      6.    Use the commit or end command.


                                    DETAILED STEPS
                                       Command or ActionPurpose
                                      Step 1 configure


                                      Example:
                                      RP/0/RP0/CPU0:router# configure
                                       

                                      Enters global configuration mode.

                                       
                                      Step 2 router ospf process-name


                                      Example:
                                      RP/0/RP0/CPU0:router(config)# router ospf 190
                                      RP/0/RP0/CPU0:router(config-ospf)#
                                      
                                       

                                      Enters a uniquely identifiable OSPF routing process. The process name is any alphanumeric string no longer than 40 characters without spaces.

                                       
                                      Step 3 mpls ldp auto-config


                                      Example:
                                      RP/0/RP0/CPU0:router(config-ospf)# mpls ldp auto-config
                                      
                                       

                                      Enables LDP auto-configuration.

                                       
                                      Step 4 area area-id


                                      Example:
                                      RP/0/RP0/CPU0:router(config-ospf)# area 8
                                      
                                       

                                      Configures an OSPF area and identifier.

                                      area-id

                                      Either a decimal value or an IP address.

                                       
                                      Step 5 interface type interface-path-id


                                      Example:
                                      RP/0/RP0/CPU0:router(config-ospf-ar)# interface pos 0/6/0/0
                                      
                                       

                                      Enables LDP auto-configuration on the specified interface.

                                      Note   

                                      LDP configurable limit for maximum number of interfaces does not apply to IGP auto-configuration interfaces.

                                       
                                      Step 6 Use the commit or end command.  

                                      commit—Saves the configuration changes and remains within the configuration session.

                                      end—Prompts user to take one of these actions:
                                      • Yes— Saves configuration changes and exits the configuration session.

                                      • No—Exits the configuration session without committing the configuration changes.

                                      • Cancel—Remains in the configuration session, without committing the configuration changes.

                                       
                                      Related Concepts

                                      Enabling LDP Auto-Configuration in an Area for a Specified OSPF Instance

                                      Perform this task to enable IGP auto-configuration in a defined area with a specified OSPF process name.

                                      You can disable auto-configuration on a per-interface basis. This lets LDP enable all IGP interfaces except those that are explicitly disabled.


                                      Note


                                      This feature is supported for IPv4 unicast family in default VRF only.


                                      SUMMARY STEPS

                                        1.    configure

                                        2.    router ospf process-name

                                        3.    area area-id

                                        4.    mpls ldp auto-config

                                        5.    interface type interface-path-id

                                        6.    Use the commit or end command.


                                      DETAILED STEPS
                                         Command or ActionPurpose
                                        Step 1 configure


                                        Example:
                                        RP/0/RP0/CPU0:router# configure
                                         

                                        Enters global configuration mode.

                                         
                                        Step 2 router ospf process-name


                                        Example:
                                        RP/0/RP0/CPU0:router(config)# router ospf 100
                                        RP/0/RP0/CPU0:router(config-ospf)# 
                                        
                                         

                                        Enters a uniquely identifiable OSPF routing process. The process name is any alphanumeric string no longer than 40 characters without spaces.

                                         
                                        Step 3 area area-id


                                        Example:
                                        RP/0/RP0/CPU0:router(config-ospf)# area 8
                                        RP/0/RP0/CPU0:router(config-ospf-ar)# 
                                        
                                         

                                        Configures an OSPF area and identifier.

                                        area-id

                                        Either a decimal value or an IP address.

                                         
                                        Step 4 mpls ldp auto-config


                                        Example:
                                        RP/0/RP0/CPU0:router(config-ospf-ar)# mpls ldp auto-config
                                        
                                         

                                        Enables LDP auto-configuration.

                                         
                                        Step 5 interface type interface-path-id


                                        Example:
                                        RP/0/RP0/CPU0:router(config-ospf-ar)# interface pos 0/6/0/0  
                                        RP/0/RP0/CPU0:router(config-ospf-ar-if)
                                        
                                         

                                        Enables LDP auto-configuration on the specified interface. The LDP configurable limit for maximum number of interfaces does not apply to IGP auto-config interfaces.

                                         
                                        Step 6 Use the commit or end command.  

                                        commit—Saves the configuration changes and remains within the configuration session.

                                        end—Prompts user to take one of these actions:
                                        • Yes— Saves configuration changes and exits the configuration session.

                                        • No—Exits the configuration session without committing the configuration changes.

                                        • Cancel—Remains in the configuration session, without committing the configuration changes.

                                         
                                        Related Concepts

                                        Disabling LDP Auto-Configuration

                                        Perform this task to disable IGP auto-configuration.

                                        You can disable auto-configuration on a per-interface basis. This lets LDP enable all IGP interfaces except those that are explicitly disabled.

                                        SUMMARY STEPS

                                          1.    configure

                                          2.    mpls ldp

                                          3.    interface type interface-path-id

                                          4.    igp auto-config disable

                                          5.    Use the commit or end command.


                                        DETAILED STEPS
                                           Command or ActionPurpose
                                          Step 1 configure


                                          Example:
                                          RP/0/RP0/CPU0:router# configure
                                           

                                          Enters global configuration mode.

                                           
                                          Step 2 mpls ldp


                                          Example:
                                          RP/0/RP0/CPU0:router(config)# mpls ldp
                                          RP/0/RP0/CPU0:router(config-ldp)# 
                                          
                                           

                                          Enters the MPLS LDP configuration mode.

                                           
                                          Step 3 interface type interface-path-id


                                          Example:
                                          RP/0/RP0/CPU0:router(config-ldp)# interface pos 0/6/0/0
                                          
                                           

                                          Enters interface configuration mode and configures an interface.

                                           
                                          Step 4 igp auto-config disable


                                          Example:
                                          RP/0/RP0/CPU0:router(config-ldp-if)# igp auto-config disable
                                          
                                           

                                          Disables auto-configuration on the specified interface.

                                           
                                          Step 5 Use the commit or end command.  

                                          commit—Saves the configuration changes and remains within the configuration session.

                                          end—Prompts user to take one of these actions:
                                          • Yes— Saves configuration changes and exits the configuration session.

                                          • No—Exits the configuration session without committing the configuration changes.

                                          • Cancel—Remains in the configuration session, without committing the configuration changes.

                                           
                                          Related Concepts

                                          Configuring LDP Nonstop Routing

                                          Perform this task to configure LDP NSR.


                                          Note


                                          By default, NSR is globally-enabled on all LDP sessions except AToM.


                                          SUMMARY STEPS

                                            1.    configure

                                            2.    mpls ldp

                                            3.    nsr

                                            4.    Use the commit or end command.

                                            5.    (Optional) show mpls ldp [vrf vrf-name] nsr statistics

                                            6.    (Optional) show mpls ldp vrf vrf-name nsr statistics neighbor

                                            7.    (Optional) show mpls ldp [ vrf vrf-name] nsr summary

                                            8.    (Optional) show mpls ldp [ vrf vrf-name] nsr pending

                                            9.    (Optional) show mpls ldp vrf vrf-name nsr pending neighbor

                                            10.    (Optional) show mpls ldp vrf all nsr summary

                                            11.    (Optional) show mpls ldp nsr summary all

                                            12.    (Optional) clear mpls ldp vrf vrf-name nsr statistics neighbor


                                          DETAILED STEPS
                                             Command or ActionPurpose
                                            Step 1 configure


                                            Example:
                                            RP/0/RP0/CPU0:router# configure
                                             

                                            Enters global configuration mode.

                                             
                                            Step 2 mpls ldp


                                            Example:
                                            RP/0/RP0/CPU0:router(config)# mpls ldp
                                            
                                             

                                            Enters the MPLS LDP configuration mode.

                                             
                                            Step 3 nsr


                                            Example:
                                            RP/0/RP0/CPU0:router(config-ldp)# nsr
                                            
                                             

                                            Enables LDP nonstop routing.

                                             
                                            Step 4 Use the commit or end command.  

                                            commit—Saves the configuration changes and remains within the configuration session.

                                            end—Prompts user to take one of these actions:
                                            • Yes— Saves configuration changes and exits the configuration session.

                                            • No—Exits the configuration session without committing the configuration changes.

                                            • Cancel—Remains in the configuration session, without committing the configuration changes.

                                             
                                            Step 5 show mpls ldp [vrf vrf-name] nsr statistics


                                            Example:
                                            RP/0/RP0/CPU0:router# show mpls ldp nsr statistics
                                            
                                            
                                            RP/0/RP0/CPU0:router# show mpls ldp vrf red nsr statistics
                                            
                                             
                                            (Optional)

                                            Displays MPLS LDP NSR statistics.

                                            Displays LDP NSR statistics for the specified VRF.

                                             
                                            Step 6show mpls ldp vrf vrf-name nsr statistics neighbor


                                            Example:
                                            RP/0/RP0/CPU0:router# show mpls ldp vrf red nsr statistics neighbor 1.1.1.1
                                            
                                             
                                            (Optional)

                                            Displays LDP NSR statistics for the specified VRF for a given neighbor.

                                             
                                            Step 7show mpls ldp [ vrf vrf-name] nsr summary


                                            Example:
                                            RP/0/RP0/CPU0:router# show mpls ldp nsr summary
                                            
                                            
                                            RP/0/RP0/CPU0:router# show mpls ldp vrf red nsr summary
                                            
                                             
                                            (Optional)

                                            Displays MPLS LDP NSR summarized information.

                                            Displays LDP NSR summarized information for the specified VRF.

                                             
                                            Step 8show mpls ldp [ vrf vrf-name] nsr pending


                                            Example:
                                            RP/0/RP0/CPU0:router# show mpls ldp nsr pending
                                            
                                            
                                            RP/0/RP0/CPU0:router# show mpls ldp vrf red nsr pending
                                            
                                             
                                            (Optional)

                                            Displays MPLS LDP NSR pending information.

                                            Displays LDP NSR pending information for the specified VRF.

                                             
                                            Step 9show mpls ldp vrf vrf-name nsr pending neighbor


                                            Example:
                                            RP/0/RP0/CPU0:router# show mpls ldp vrf red nsr pending neighbor 2.2.2.2
                                            
                                             
                                            (Optional)

                                            Displays LDP NSR pending information for the specified VRF for a given neighbor.

                                             
                                            Step 10show mpls ldp vrf all nsr summary


                                            Example:
                                            RP/0/RP0/CPU0:router# show mpls ldp vrf all nsr summary
                                            
                                             
                                            (Optional)

                                            Displays all LDP configured VRF (including default VRF) summarized information.

                                             
                                            Step 11show mpls ldp nsr summary all


                                            Example:
                                            RP/0/RP0/CPU0:router# show mpls ldp nsr summary all
                                            
                                             
                                            (Optional)

                                            Displays aggregate summary across LDP processes and all VRFs.

                                             
                                            Step 12clear mpls ldp vrf vrf-name nsr statistics neighbor


                                            Example:
                                            RP/0/RP0/CPU0:router# clear mpls ldp vrf red nsr statistics neighbor
                                            
                                             
                                            (Optional)

                                            Resets LDP NSR statistics for the specified VRF for neighbor.

                                             
                                            Related Concepts

                                            Configuring LDP Downstream on Demand mode

                                            SUMMARY STEPS

                                              1.    configure

                                              2.    mpls ldp

                                              3.    [vrf vrf-name session] downstream-on-demand

                                              4.    Use the commit or end command.


                                            DETAILED STEPS
                                               Command or ActionPurpose
                                              Step 1 configure


                                              Example:
                                              RP/0/RP0/CPU0:router# configure
                                               

                                              Enters global configuration mode.

                                               
                                              Step 2 mpls ldp


                                              Example:
                                              RP/0/RP0/CPU0:router(config)# mpls ldp
                                              
                                               

                                              Enters MPLS LDP configuration mode.

                                               
                                              Step 3[vrf vrf-name session] downstream-on-demand


                                              Example:
                                              RP/0/RP0/CPU0:router(config-ldp)# vrf red session downstream-on-demand with ABC 
                                              
                                               

                                              (Optional) Enters downstream on demand label advertisement mode under the specified non-default VRF.

                                              Enters downstream on demand label advertisement mode. The ACL contains the list of peer IDs that are configured for downstream-on-demand mode. When the ACL is changed or configured, the list of established neighbor is traversed.

                                               
                                              Step 4 Use the commit or end command.  

                                              commit—Saves the configuration changes and remains within the configuration session.

                                              end—Prompts user to take one of these actions:
                                              • Yes— Saves configuration changes and exits the configuration session.

                                              • No—Exits the configuration session without committing the configuration changes.

                                              • Cancel—Remains in the configuration session, without committing the configuration changes.

                                               
                                              Related Concepts

                                              Redistributing MPLS LDP Routes into BGP

                                              Perform this task to redistribute Border Gateway Protocol (BGP) autonomous system into an MPLS LDP.

                                              SUMMARY STEPS

                                                1.    configure

                                                2.    mpls ldp

                                                3.    redistribute bgp

                                                4.    end or commit

                                                5.    show run mpls ldp


                                              DETAILED STEPS
                                                 Command or ActionPurpose
                                                Step 1 configure


                                                Example:
                                                RP/0/RP0/CPU0:router# configure
                                                
                                                
                                                 

                                                Enters Global Configuration mode.

                                                 
                                                Step 2 mpls ldp


                                                Example:
                                                RP/0/RP0/CPU0:router(config)# mpls ldp
                                                
                                                
                                                 

                                                Enters MPLS LDP configuration mode.

                                                 
                                                Step 3 redistribute bgp


                                                Example:
                                                RP/0/RP0/CPU0:router(config-ldp)# redistribute bgp advertise-to acl_1
                                                
                                                
                                                 

                                                Allows the redistribution of BGP routes into an MPLS LDP processes.

                                                Note   

                                                Autonomous system numbers (ASNs) are globally unique identifiers used to identify autonomous systems (ASs) and enable ASs to exchange exterior routing information between neighboring ASs. A unique ASN is allocated to each AS for use in BGP routing. ASNs are encoded as 2-byte numbers and 4-byte numbers in BGP.

                                                 
                                                Step 4end or commit  
                                                • When you issue the end command, the system prompts you to commit changes:

                                                  
                                                  Uncommitted changes found, commit them before
                                                  exiting(yes/no/cancel)?
                                                  [cancel]:
                                                  
                                                • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

                                                • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

                                                • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

                                                • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

                                                 
                                                Step 5 show run mpls ldp


                                                Example:
                                                RP/0/RP0/CPU0:router# show run mpls ldp
                                                
                                                
                                                 

                                                Displays information about the redistributed route information.

                                                 

                                                Enabling MLDP

                                                Perform this task to enable Multicast Label Distribution Protocol (MLDP) in MPLS LDP.

                                                SUMMARY STEPS

                                                  1.    configure

                                                  2.    mpls ldp

                                                  3.    mldp

                                                  4.    end or commit


                                                DETAILED STEPS
                                                   Command or ActionPurpose
                                                  Step 1 configure


                                                  Example:
                                                  RP/0/RP0/CPU0:router# configure
                                                   

                                                  Enters global configuration mode.

                                                   
                                                  Step 2 mpls ldp


                                                  Example:
                                                  RP/0/RP0/CPU0:router(config)# mpls ldp
                                                  
                                                   

                                                  Enters the MPLS LDP configuration mode.

                                                   
                                                  Step 3 mldp


                                                  Example:
                                                  RP/0/RP0/CPU0:router(config-ldp)# mldp
                                                  
                                                  RP/0/RP0/CPU0:router(config-ldp-mldp)# 
                                                  
                                                   

                                                  Enables MLDP.

                                                   
                                                  Step 4end or commit

                                                  Example:
                                                  
                                                  RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp)# end
                                                  

                                                  or

                                                  RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp)# commit
                                                  
                                                   
                                                  • When you issue the end command, the system prompts you to commit changes:

                                                    
                                                    Uncommitted changes found, commit them before
                                                    exiting(yes/no/cancel)?
                                                    [cancel]:
                                                    
                                                  • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

                                                  • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

                                                  • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

                                                  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

                                                   

                                                  Enabling MLDP Make-Before-Break

                                                  Perform this task to enable the make-before-break (MBB) feature in MPLS MLDP.

                                                  SUMMARY STEPS

                                                    1.    configure

                                                    2.    mpls ldp

                                                    3.    mldp

                                                    4.    address-family ipv4

                                                    5.    make-before-break [delay seconds]

                                                    6.    end or commit


                                                  DETAILED STEPS
                                                     Command or ActionPurpose
                                                    Step 1 configure


                                                    Example:
                                                    RP/0/RP0/CPU0:router# configure
                                                    
                                                    
                                                     

                                                    Enters Global Configuration mode.

                                                     
                                                    Step 2mpls ldp


                                                    Example:
                                                    RP/0/RP0/CPU0:router(config)# mpls ldp
                                                    
                                                    
                                                     

                                                    Enters MPLS LDP configuration mode.

                                                     
                                                    Step 3mldp


                                                    Example:
                                                    RP/0/RP0/CPU0:router(config-ldp)# mldp
                                                    
                                                    
                                                     

                                                    Enables MLDP.

                                                     
                                                    Step 4address-family ipv4


                                                    Example:
                                                    RP/0/RP0/CPU0:router(config-ldp-mldp)# address-family ipv4
                                                    
                                                    
                                                     

                                                    Enables MLDP for IPv4 address family.

                                                     
                                                    Step 5make-before-break [delay seconds]


                                                    Example:
                                                    RP/0/RP0/CPU0:router(config-ldp-mldp-af)# make-before-break delay 10
                                                    
                                                    
                                                     

                                                    Enables the make-before-break feature.

                                                    (Optional) Configures the MBB forwarding delay in seconds. Range is 0 to 600.

                                                     
                                                    Step 6end or commit

                                                    Example:
                                                    
                                                    RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# end
                                                    

                                                    or

                                                    RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# commit
                                                    
                                                     
                                                    • When you issue the end command, the system prompts you to commit changes:

                                                      
                                                      Uncommitted changes found, commit them before
                                                      exiting(yes/no/cancel)?
                                                      [cancel]:
                                                      
                                                    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

                                                    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

                                                    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

                                                    • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

                                                     

                                                    Enabling MLDP MoFRR

                                                    Perform this task to enable multicast only fast reroute (MoFRR) support in MPLS MLDP.

                                                    SUMMARY STEPS

                                                      1.    configure

                                                      2.    mpls ldp

                                                      3.    mldp

                                                      4.    address-family ipv4

                                                      5.    mofrr

                                                      6.    end or commit


                                                    DETAILED STEPS
                                                       Command or ActionPurpose
                                                      Step 1 configure


                                                      Example:
                                                      RP/0/RP0/CPU0:router# configure
                                                      
                                                      
                                                       

                                                      Enters Global Configuration mode.

                                                       
                                                      Step 2mpls ldp


                                                      Example:
                                                      RP/0/RP0/CPU0:router(config)# mpls ldp
                                                      
                                                      
                                                       

                                                      Enters MPLS LDP configuration mode.

                                                       
                                                      Step 3mldp


                                                      Example:
                                                      RP/0/RP0/CPU0:router(config-ldp)# mldp
                                                      
                                                      
                                                       

                                                      Enables MLDP.

                                                       
                                                      Step 4address-family ipv4


                                                      Example:
                                                      RP/0/RP0/CPU0:router(config-ldp-mldp)# address-family ipv4
                                                      
                                                      
                                                       

                                                      Enables MLDP for IPv4 address family.

                                                       
                                                      Step 5mofrr


                                                      Example:
                                                      RP/0/RP0/CPU0:router(config-ldp-mldp-af)# mofrr
                                                      
                                                      
                                                       

                                                      Enables MoFRR support.

                                                       
                                                      Step 6end or commit

                                                      Example:
                                                      
                                                      RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# end
                                                      

                                                      or

                                                      RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# commit
                                                      
                                                       
                                                      • When you issue the end command, the system prompts you to commit changes:

                                                        
                                                        Uncommitted changes found, commit them before
                                                        exiting(yes/no/cancel)?
                                                        [cancel]:
                                                        
                                                      • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

                                                      • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

                                                      • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

                                                      • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

                                                       

                                                      Enabling MLDP Recursive FEC

                                                      Perform this task to enable recursive forwarding equivalence class (FEC) support in MPLS MLDP.

                                                      SUMMARY STEPS

                                                        1.    configure

                                                        2.    mpls ldp

                                                        3.    mldp

                                                        4.    address-family ipv4

                                                        5.    recursive-fec

                                                        6.    end or commit


                                                      DETAILED STEPS
                                                         Command or ActionPurpose
                                                        Step 1 configure


                                                        Example:
                                                        RP/0/RP0/CPU0:router# configure
                                                        
                                                        
                                                         

                                                        Enters Global Configuration mode.

                                                         
                                                        Step 2mpls ldp


                                                        Example:
                                                        RP/0/RP0/CPU0:router(config)# mpls ldp
                                                        
                                                        
                                                         

                                                        Enters MPLS LDP configuration mode.

                                                         
                                                        Step 3mldp


                                                        Example:
                                                        RP/0/RP0/CPU0:router(config-ldp)# mldp
                                                        
                                                        
                                                         

                                                        Enables MLDP.

                                                         
                                                        Step 4address-family ipv4


                                                        Example:
                                                        RP/0/RP0/CPU0:router(config-ldp-mldp)# address-family ipv4
                                                        
                                                        
                                                         

                                                        Enables MLDP for IPv4 address family.

                                                         
                                                        Step 5recursive-fec


                                                        Example:
                                                        RP/0/RP0/CPU0:router(config-ldp-mldp-af)# recursive-fec
                                                        
                                                        
                                                         

                                                        Enables recursive FEC support.

                                                         
                                                        Step 6end or commit

                                                        Example:
                                                        
                                                        RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# end
                                                        

                                                        or

                                                        RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# commit
                                                        
                                                         
                                                        • When you issue the end command, the system prompts you to commit changes:

                                                          
                                                          Uncommitted changes found, commit them before
                                                          exiting(yes/no/cancel)?
                                                          [cancel]:
                                                          
                                                        • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

                                                        • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

                                                        • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

                                                        • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

                                                         

                                                        Enabling MLDP Static Multipoint to Multipoint LSP

                                                        Perform this task to enable static multipoint to multipoint (MP2MP) LSP support in MPLS MLDP.

                                                        SUMMARY STEPS

                                                          1.    configure

                                                          2.    mpls ldp

                                                          3.    mldp

                                                          4.    address-family ipv4

                                                          5.    static mp2mp ip-address

                                                          6.    end or commit


                                                        DETAILED STEPS
                                                           Command or ActionPurpose
                                                          Step 1 configure


                                                          Example:
                                                          RP/0/RP0/CPU0:router# configure
                                                          
                                                          
                                                           

                                                          Enters Global Configuration mode.

                                                           
                                                          Step 2mpls ldp


                                                          Example:
                                                          RP/0/RP0/CPU0:router(config)# mpls ldp
                                                          
                                                          
                                                           

                                                          Enters MPLS LDP configuration mode.

                                                           
                                                          Step 3mldp


                                                          Example:
                                                          RP/0/RP0/CPU0:router(config-ldp)# mldp
                                                          
                                                          
                                                           

                                                          Enables MLDP.

                                                           
                                                          Step 4address-family ipv4


                                                          Example:
                                                          RP/0/RP0/CPU0:router(config-ldp-mldp)# address-family ipv4
                                                          
                                                          
                                                           

                                                          Enables MLDP for IPv4 address family.

                                                           
                                                          Step 5static mp2mp ip-address


                                                          Example:
                                                          RP/0/RP0/CPU0:router(config-ldp-mldp-af)# static mp2mp 10.10.10.10 1
                                                          
                                                          
                                                           

                                                          Enables static MP2MP LSP support and specifies MP2MP LSP root IP address followed by the number of LSPs in the range 1 to 1000.

                                                           
                                                          Step 6end or commit

                                                          Example:
                                                          
                                                          RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# end
                                                          

                                                          or

                                                          RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# commit
                                                          
                                                           
                                                          • When you issue the end command, the system prompts you to commit changes:

                                                            
                                                            Uncommitted changes found, commit them before
                                                            exiting(yes/no/cancel)?
                                                            [cancel]:
                                                            
                                                          • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

                                                          • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

                                                          • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

                                                          • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

                                                           

                                                          Enabling MLDP Static Point to Multipoint LSP

                                                          Perform this task to enable static point to multipoint (P2MP) LSP support in MPLS MLDP.

                                                          SUMMARY STEPS

                                                            1.    configure

                                                            2.    mpls ldp

                                                            3.    mldp

                                                            4.    address-family ipv4

                                                            5.    static p2mp ip-address

                                                            6.    end or commit


                                                          DETAILED STEPS
                                                             Command or ActionPurpose
                                                            Step 1 configure


                                                            Example:
                                                            RP/0/RP0/CPU0:router# configure
                                                            
                                                            
                                                             

                                                            Enters Global Configuration mode.

                                                             
                                                            Step 2mpls ldp


                                                            Example:
                                                            RP/0/RP0/CPU0:router(config)# mpls ldp
                                                            
                                                            
                                                             

                                                            Enters MPLS LDP configuration mode.

                                                             
                                                            Step 3mldp


                                                            Example:
                                                            RP/0/RP0/CPU0:router(config-ldp)# mldp
                                                            
                                                            
                                                             

                                                            Enables MLDP.

                                                             
                                                            Step 4address-family ipv4


                                                            Example:
                                                            RP/0/RP0/CPU0:router(config-ldp-mldp)# address-family ipv4
                                                            
                                                            
                                                             

                                                            Enables MLDP for IPv4 address family.

                                                             
                                                            Step 5static p2mp ip-address


                                                            Example:
                                                            RP/0/RP0/CPU0:router(config-ldp-mldp-af)# static p2mp 1.1.1.1 1
                                                            
                                                            
                                                             

                                                            Enables static P2MP LSP support and specifies P2MP LSP root IP address followed by the number of LSPs in the range 1 to 1000.

                                                             
                                                            Step 6end or commit

                                                            Example:
                                                            
                                                            RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# end
                                                            

                                                            or

                                                            RP/0/RP/0/RP0/CPU0:router (config-ldp-mldp-af)# commit
                                                            
                                                             
                                                            • When you issue the end command, the system prompts you to commit changes:

                                                              
                                                              Uncommitted changes found, commit them before
                                                              exiting(yes/no/cancel)?
                                                              [cancel]:
                                                              
                                                            • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

                                                            • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

                                                            • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

                                                            • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

                                                             

                                                            Disabling MLDP

                                                            Perform this task to disable MLDP on Label Distribution Protocol (LDP) enabled interfaces.

                                                            SUMMARY STEPS

                                                              1.    configure

                                                              2.    mpls ldp

                                                              3.    interface type interface-path-id

                                                              4.    address-family {ipv4 }

                                                              5.    igp mldp disable

                                                              6.    Use the commit or end command.


                                                            DETAILED STEPS
                                                               Command or ActionPurpose
                                                              Step 1 configure


                                                              Example:
                                                              RP/0/RP0/CPU0:router# configure
                                                              
                                                              
                                                               

                                                              Enters Global Configuration mode.

                                                               
                                                              Step 2mpls ldp


                                                              Example:
                                                              RP/0/RP0/CPU0:router(config)# mpls ldp
                                                              
                                                              
                                                               

                                                              Enters MPLS LDP configuration mode.

                                                               
                                                              Step 3 interface type interface-path-id


                                                              Example:
                                                              RP/0/RP0/CPU0:router(config-ldp)# interface POS 0/1/0/0
                                                              
                                                               

                                                              Enters interface configuration mode for the LDP protocol.

                                                               
                                                              Step 4 address-family {ipv4 }


                                                              Example:
                                                              RP/0/RP0/CPU0:router(config-ldp-if)# address-family ipv4
                                                              

                                                              or

                                                               

                                                              Enables the LDP IPv4 address family.

                                                               
                                                              Step 5 igp mldp disable


                                                              Example:
                                                              RP/0/RP0/CPU0:router(config-ldp-if-af)# igp mldp disable
                                                              
                                                               

                                                              Disables MLDP.

                                                               
                                                              Step 6 Use the commit or end command.  

                                                              commit—Saves the configuration changes and remains within the configuration session.

                                                              end—Prompts user to take one of these actions:
                                                              • Yes— Saves configuration changes and exits the configuration session.

                                                              • No—Exits the configuration session without committing the configuration changes.

                                                              • Cancel—Remains in the configuration session, without committing the configuration changes.

                                                               

                                                              Configuration Examples for Implementing MPLS LDP

                                                              These configuration examples are provided to implement LDP:

                                                              Configuring LDP with Graceful Restart: Example

                                                              The example shows how to enable LDP with graceful restart on the POS interface 0/2/0/0.

                                                                mpls ldp
                                                                 graceful-restart
                                                                 interface pos0/2/0/0
                                                                !
                                                                

                                                              Configuring LDP Discovery: Example

                                                              The example shows how to configure LDP discovery parameters.

                                                                mpls ldp
                                                                 router-id 192.168.70.1
                                                                 discovery hello holdtime 15
                                                                 discovery hello interval 5
                                                                !
                                                                
                                                                show mpls ldp parameters
                                                                show mpls ldp discovery
                                                                

                                                              Configuring LDP Link: Example

                                                              The example shows how to configure LDP link parameters.

                                                                mpls ldp
                                                                 interface pos 0/1/0/0
                                                                 !
                                                                !
                                                                
                                                                show mpls ldp discovery
                                                                
                                                              Related Concepts

                                                              Configuring LDP Discovery for Targeted Hellos: Example

                                                              The examples show how to configure LDP Discovery to accept targeted hello messages.

                                                              Active (tunnel head)

                                                                mpls ldp
                                                                 router-id 192.168.70.1
                                                                 interface tunnel-te 12001
                                                                 !
                                                                !
                                                                

                                                              Passive (tunnel tail)

                                                                mpls ldp
                                                                 router-id 192.168.70.2
                                                                 discovery targeted-hello accept
                                                                !
                                                                
                                                              Related Concepts

                                                              Configuring Label Advertisement (Outbound Filtering): Example

                                                              The example shows how to configure LDP label advertisement control.

                                                                 mpls ldp 
                                                                    address-family ipv4
                                                                      label local advertise
                                                                         disable
                                                                         for pfx_acl_1 to peer_acl_1
                                                                         for pfx_acl_2 to peer_acl_2
                                                                         for pfx_acl_3
                                                                         interface POS 0/1/0/0
                                                                         interface POS 0/2/0/0
                                                                     !
                                                                   !
                                                                
                                                              		ipv4 access-list pfx_acl_1
                                                                    10 permit ipv4 host 1.0.0.0 any
                                                                !
                                                                ipv4 access-list pfx_acl_2
                                                                    10 permit ipv4 host 2.0.0.0 any
                                                                !
                                                                ipv4 access-list peer_acl_1
                                                                    10 permit ipv4 host 1.1.1.1 any
                                                                    20 permit ipv4 host 1.1.1.2 any
                                                                !
                                                                ipv4 access-list peer_acl_2
                                                                    10 permit ipv4 host 2.2.2.2 any
                                                                !
                                                               !   
                                                                
                                                               show mpls ldp binding
                                                                

                                                              Configuring LDP Neighbors: Example

                                                              The example shows how to disable label advertisement.

                                                               			
                                                                mpls ldp 
                                                                   address-family ipv4
                                                                     label local advertise
                                                                       disable
                                                                     !
                                                                   !
                                                                !
                                                              
                                                              

                                                              Configuring LDP Forwarding: Example

                                                              The example shows how to configure LDP forwarding.

                                                                mpls ldp
                                                                 address-family ipv4 
                                                                 label local advertise explicit-null
                                                                !
                                                                
                                                                show mpls ldp forwarding
                                                                show mpls forwarding
                                                                
                                                              Related Concepts

                                                              Configuring LDP Nonstop Forwarding with Graceful Restart: Example

                                                              The example shows how to configure LDP nonstop forwarding with graceful restart.

                                                                mpls ldp 
                                                                log
                                                                graceful-restart
                                                                !
                                                                 graceful-restart
                                                                 graceful-restart forwarding state-holdtime 180
                                                                 graceful-restart reconnect-timeout 15
                                                                 interface pos0/1/0/0
                                                                !
                                                                
                                                                show mpls ldp graceful-restart
                                                                show mpls ldp neighbor gr
                                                                show mpls ldp forwarding
                                                                show mpls forwarding
                                                                

                                                              Configuring Label Acceptance (Inbound Filtering): Example

                                                              The example shows how to configure inbound label filtering.

                                                              
                                                                mpls ldp
                                                                 address-family ipv4
                                                                  label remote accept from 192.168.1.1:0 for pfx_acl_2
                                                                  !
                                                                 !
                                                                !
                                                                

                                                              Configuring Local Label Allocation Control: Example

                                                              The example shows how to configure local label allocation control.

                                                              
                                                               mpls ldp
                                                                address-family ipv4
                                                                 label local allocate for pfx_acl_1
                                                                 ! 
                                                                !
                                                              

                                                              Configuring LDP Session Protection: Example

                                                              The example shows how to configure session protection.

                                                                mpls ldp
                                                                 session protection for peer_acl_1 duration 
                                                              60
                                                                !
                                                                
                                                              Related Concepts

                                                              Configuring LDP IGP Synchronization—OSPF: Example

                                                              The example shows how to configure LDP IGP synchronization for OSPF.

                                                                router ospf 100
                                                                mpls ldp sync
                                                                !
                                                                mpls ldp
                                                                 igp sync delay 30
                                                                !
                                                                
                                                              Related Concepts

                                                              Configuring LDP IGP Synchronization—ISIS: Example

                                                              The example shows how to configure LDP IGP synchronization.

                                                                router isis 100
                                                                 interface POS 0/2/0/0
                                                                address-family ipv4 unicast
                                                                mpls ldp sync
                                                                !
                                                                 !
                                                                !
                                                                mpls ldp
                                                                 igp sync delay 30
                                                                !
                                                                
                                                              Related Concepts

                                                              Configuring LDP Auto-Configuration: Example

                                                              The example shows how to configure the IGP auto-configuration feature globally for a specific OSPF interface ID.

                                                                router ospf 100
                                                                 mpls ldp auto-config
                                                                 area 0 
                                                                  interface pos 1/1/1/1
                                                                
                                                                

                                                              The example shows how to configure the IGP auto-configuration feature on a given area for a given OSPF interface ID.

                                                                router ospf 100
                                                                 area 0
                                                                  mpls ldp auto-config
                                                                  interface pos 1/1/1/1
                                                                
                                                              Related Concepts

                                                              Configure IP LDP Fast Reroute Loop Free Alternate: Examples

                                                              This example shows how to configure LFA FRR with default tie-break configuration:

                                                              
                                                              router isis TEST
                                                               net 49.0001.0000.0000.0001.00
                                                               address-family ipv4 unicast
                                                                metric-style wide
                                                              
                                                               interface GigabitEthernet0/6/0/13
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                                 fast-reroute per-prefix
                                                                 # primary path GigabitEthernet0/6/0/13 will exclude the interface
                                                                 # GigabitEthernet0/6/0/33 in LFA backup path computation. 
                                                                 fast-reroute per-prefix exclude interface GigabitEthernet0/6/0/33
                                                              !
                                                               interface GigabitEthernet0/6/0/23
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                              !
                                                               interface GigabitEthernet0/6/0/24
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                              !
                                                               interface GigabitEthernet0/6/0/33
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                              !
                                                              
                                                              

                                                              This example shows how to configure TE tunnel as LFA backup:

                                                              
                                                              router isis TEST
                                                               net 49.0001.0000.0000.0001.00
                                                               address-family ipv4 unicast
                                                                metric-style wide
                                                              
                                                               interface GigabitEthernet0/6/0/13
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                                 fast-reroute per-prefix
                                                                 # primary path GigabitEthernet0/6/0/13 will exclude the interface
                                                                 # GigabitEthernet0/6/0/33 in LFA backup path computation. TE tunnel 1001
                                                                 # is using the link GigabitEthernet0/6/0/33.
                                                                 fast-reroute per-prefix exclude interface GigabitEthernet0/6/0/33
                                                                 fast-reroute per-prefix lfa-candidate interface tunnel-te1001
                                                              !
                                                               interface GigabitEthernet0/6/0/33
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                              !
                                                              

                                                              This example shows how to configure LFA FRR with configurable tie-break configuration:

                                                              
                                                              router isis TEST
                                                               net 49.0001.0000.0000.0001.00
                                                               address-family ipv4 unicast
                                                                metric-style wide
                                                                fast-reroute per-prefix tiebreaker ?
                                                                downstream            Prefer backup path via downstream node
                                                                lc-disjoint           Prefer line card disjoint backup path
                                                                lowest-backup-metric  Prefer backup path with lowest total metric
                                                                node-protecting       Prefer node protecting backup path
                                                                primary-path          Prefer backup path from ECMP set
                                                                secondary-path        Prefer non-ECMP backup path
                                                              
                                                                fast-reroute per-prefix tiebreaker lc-disjoint index ?
                                                                <1-255>  Index
                                                                fast-reroute per-prefix tiebreaker lc-disjoint index 10
                                                              
                                                              Sample configuration:
                                                              
                                                              router isis TEST
                                                               net 49.0001.0000.0000.0001.00
                                                               address-family ipv4 unicast
                                                                metric-style wide
                                                                fast-reroute per-prefix tiebreaker downstream index 60
                                                                fast-reroute per-prefix tiebreaker lc-disjoint index 10
                                                                fast-reroute per-prefix tiebreaker lowest-backup-metric index 40
                                                                fast-reroute per-prefix tiebreaker node-protecting index 30
                                                                fast-reroute per-prefix tiebreaker primary-path index 20
                                                                fast-reroute per-prefix tiebreaker secondary-path index 50
                                                              !
                                                              interface GigabitEthernet0/6/0/13
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                                 fast-reroute per-prefix
                                                              !  
                                                               interface GigabitEthernet0/1/0/13
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                                 fast-reroute per-prefix
                                                              !
                                                               interface GigabitEthernet0/3/0/0.1
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                              !
                                                               interface GigabitEthernet0/3/0/0.2
                                                                point-to-point
                                                                address-family ipv4 unicast
                                                              

                                                              Verify IP LDP Fast Reroute Loop Free Alternate: Example

                                                              The following examples show how to verify the IP LDP FRR LFA feature on the router.

                                                              The following example shows how to verify ISIS FRR output:

                                                              
                                                              RP/0/RP0/CPU0:router#show isis fast-reroute summary
                                                              
                                                              IS-IS 1 IPv4 Unicast FRR summary
                                                              
                                                                                        Critical   High       Medium     Low        Total     
                                                                                        Priority   Priority   Priority   Priority             
                                                              Prefixes reachable in L1
                                                                All paths protected     0          0          4          1008       1012      
                                                                Some paths protected    0          0          0          0          0         
                                                                Unprotected             0          0          0          0          0         
                                                                Protection coverage     0.00%      0.00%      100.00%    100.00%    100.00%   
                                                              Prefixes reachable in L2
                                                                All paths protected     0          0          1          0          1         
                                                                Some paths protected    0          0          0          0          0         
                                                                Unprotected             0          0          0          0          0         
                                                                Protection coverage     0.00%      0.00%      100.00%    0.00%      100.00%   
                                                              
                                                              
                                                              The following example shows how to verify the IGP route 211.1.1.1/24 in ISIS Fast Reroute output:
                                                              RP/0/RP0/CPU0:router#show isis fast-reroute 211.1.1.1/24
                                                              
                                                              L1 211.1.1.1/24 [40/115]
                                                                   via 12.0.0.2, GigabitEthernet0/6/0/13, NORTH
                                                                     FRR backup via 14.0.2.2, GigabitEthernet0/6/0/0.3, SOUTH
                                                              
                                                              RP/0/RP0/CPU0:router#show isis fast-reroute 211.1.1.1/24 detail
                                                              
                                                              L1 211.1.1.1/24 [40/115] low priority
                                                                   via 12.0.0.2, GigabitEthernet0/6/0/13, NORTH
                                                                     FRR backup via 14.0.2.2, GigabitEthernet0/6/0/0.3, SOUTH
                                                                     P: No, TM: 130, LC: No, NP: Yes, D: Yes
                                                                   src sr1.00-00, 173.1.1.2
                                                                 L2 adv [40] native, propagated
                                                              
                                                              
                                                              The following example shows how to verify the IGP route 211.1.1.1/24 in RIB output:
                                                              
                                                              RP/0/RP0/CPU0:router#show route 211.1.1.1/24
                                                              
                                                              Routing entry for 211.1.1.0/24
                                                                Known via "isis 1", distance 115, metric 40, type level-1
                                                                Installed Nov 27 10:22:20.311 for 1d08h
                                                                Routing Descriptor Blocks
                                                                  12.0.0.2, from 173.1.1.2, via GigabitEthernet0/6/0/13, Protected
                                                                    Route metric is 40
                                                                  14.0.2.2, from 173.1.1.2, via GigabitEthernet0/6/0/0.3, Backup
                                                                    Route metric is 0
                                                                No advertising protos. 
                                                              
                                                              
                                                              The following example shows how to verify the IGP route 211.1.1.1/24 in FIB output:
                                                              
                                                              RP/0/RP0/CPU0:router#show cef 211.1.1.1/24
                                                              211.1.1.0/24, version 0, internal 0x40040001 (ptr 0x9d9e1a68) [1], 0x0               \
                                                              (0x9ce0ec40), 0x4500 (0x9e2c69e4)
                                                               Updated Nov 27 10:22:29.825 
                                                               remote adjacency to GigabitEthernet0/6/0/13
                                                               Prefix Len 24, traffic index 0, precedence routine (0)
                                                                 via 12.0.0.2, GigabitEthernet0/6/0/13, 0 dependencies, weight 0, class 0,         \
                                                              protected [flags 0x400]
                                                                  path-idx 0, bkup-idx 1 [0x9e5b71b4 0x0]
                                                                  next hop 12.0.0.2
                                                                   local label 16080      labels imposed {16082}
                                                                 via 14.0.2.2, GigabitEthernet0/6/0/0.3, 3 dependencies, weight 0, class 0,        \
                                                              backup [flags 0x300]
                                                                  path-idx 1
                                                                  next hop 14.0.2.2
                                                                  remote adjacency
                                                                   local label 16080      labels imposed {16079}
                                                              
                                                              RP/0/RP0/CPU0:router#show cef 211.1.1.1/24 detail
                                                              211.1.1.0/24, version 0, internal 0x40040001 (ptr 0x9d9e1a68) [1], 0x0               \
                                                              (0x9ce0ec40), 0x4500 (0x9e2c69e4)
                                                               Updated Nov 27 10:22:29.825 
                                                               remote adjacency to GigabitEthernet0/6/0/13
                                                               Prefix Len 24, traffic index 0, precedence routine (0)
                                                                gateway array (0x9cc622f0) reference count 1158, flags 0x28000d00, source lsd      \
                                                              (2), 
                                                                              [387 type 5 flags 0x101001 (0x9df32398) ext 0x0 (0x0)]
                                                                LW-LDI[type=5, refc=3, ptr=0x9ce0ec40, sh-ldi=0x9df32398]
                                                                 via 12.0.0.2, GigabitEthernet0/6/0/13, 0 dependencies, weight 0, class 0,         \
                                                              protected [flags 0x400]
                                                                  path-idx 0, bkup-idx 1 [0x9e5b71b4 0x0]
                                                                  next hop 12.0.0.2
                                                                   local label 16080      labels imposed {16082}
                                                                 via 14.0.2.2, GigabitEthernet0/6/0/0.3, 3 dependencies, weight 0, class 0,        \
                                                              backup [flags 0x300]
                                                                  path-idx 1
                                                                  next hop 14.0.2.2
                                                                  remote adjacency
                                                                   local label 16080      labels imposed {16079}
                                                              
                                                              
                                                                  Load distribution: 0 (refcount 387)
                                                              
                                                                  Hash  OK  Interface                 Address
                                                                  0     Y   GigabitEthernet0/6/0/13   remote         
                                                              
                                                              
                                                              

                                                              The following example shows how to verify the IGP route 211.1.1.1/24 in MPLS LDP output:

                                                              
                                                              RP/0/RP0/CPU0:router#show mpls ldp forwarding 211.1.1.1/24
                                                              
                                                              Prefix           Label   Label      Outgoing     Next Hop            GR Stale
                                                                               In      Out        Interface                                
                                                              ---------------- ------- ---------- ------------ ------------------- -- -----
                                                              211.1.1.0/24     16080   16082      Gi0/6/0/13   12.0.0.2            Y  N
                                                                                       16079      Gi0/6/0/0.3  14.0.2.2 (!)        Y  N
                                                              
                                                              
                                                              
                                                              RP/0/RP0/CPU0:router#show mpls ldp forwarding 211.1.1.1/24 detail
                                                              
                                                              Prefix           Label   Label      Outgoing     Next Hop            GR Stale
                                                                               In      Out        Interface                                
                                                              ---------------- ------- ---------- ------------ ------------------- -- -----
                                                              211.1.1.0/24     16080   16082      Gi0/6/0/13   12.0.0.2            Y  N
                                                                                       [ Protected; path-id 1 backup-path-id 33; 
                                                                                         peer 20.20.20.20:0 ]
                                                                                       16079      Gi0/6/0/0.3  14.0.2.2 (!)        Y  N
                                                                                       [ Backup; path-id 33; peer 40.40.40.40:0 ]
                                                                Routing update   : Nov 27 10:22:19.560 (1d08h ago)
                                                                Forwarding update: Nov 27 10:22:29.060 (1d08h ago)
                                                              
                                                              

                                                              MPLS LDP CSC for Multiple VRFs Configuration: Examples

                                                              This figure shows a L3VPN LDP CSC topology that uses either BGP or LDP between PE and CE routers to distribute routes and MPLS labels.

                                                              L3VPN CSC VPN: LDP / BGP

                                                              
                                                              CE13 ---
                                                                        \      
                                                                CE12 --- PE1 ---------- PE2 
                                                                        // \               \
                                                                      //     \               \
                                                                    //         \               \
                                                                 CE11            \              CE21
                                                                    \              \           /
                                                                      \              \        / 
                                                                        \              \     /
                                                                         PE11 --------- PE22
                                                              
                                                              

                                                              VRF red: CE11, CE21

                                                              VRF blue: CE12, CE13 (local only switching)

                                                              Multi-home CEs: CE11, CE21

                                                              LDP CSC: PE1/PE11 with CE1x

                                                              BGP CSC: PE2/PE22 with CE2x

                                                              CSC-CE11 Configuration
                                                              hostname ce11
                                                              
                                                              interface Loopback0
                                                               ipv4 address 11.11.11.11 255.255.255.255
                                                              !
                                                              interface POS0/2/0/0
                                                               ipv4 address 192.168.1.11 255.255.255.0
                                                              !
                                                              interface POS0/2/0/1
                                                               ipv4 address 192.168.2.11 255.255.255.0
                                                              !
                                                              interface POS0/2/0/2
                                                               ipv4 address 192.168.3.11 255.255.255.0
                                                              !
                                                              router ospf 100
                                                               log adjacency changes
                                                               router-id 11.11.11.11
                                                               area 0
                                                                interface Loopback0
                                                                !
                                                                interface POS0/2/0/0
                                                                !
                                                                interface POS0/2/0/1
                                                                !
                                                                interface POS0/2/0/2
                                                                !
                                                               !
                                                              !
                                                              mpls ldp
                                                               log
                                                                adjacency
                                                                neighbor
                                                               !
                                                               router-id 11.11.11.11
                                                               address-family ipv4
                                                               !
                                                               interface POS0/2/0/0
                                                                address-family ipv4
                                                                !
                                                               !
                                                               interface POS0/2/0/1
                                                                address-family ipv4
                                                                !
                                                               !
                                                               interface POS0/2/0/2
                                                                address-family ipv4
                                                                !
                                                               !
                                                              !
                                                              no interface POS0/2/0/0 shut
                                                              no interface POS0/2/0/1 shut
                                                              no interface POS0/2/0/2 shut
                                                              end
                                                              
                                                              
                                                              CSC-CE12 Configuration
                                                              
                                                              hostname ce12
                                                              
                                                              interface Loopback0
                                                               ipv4 address 11.11.11.12 255.255.255.255
                                                              !
                                                              interface POS0/2/0/0
                                                               ipv4 address 192.169.1.12 255.255.255.0
                                                              !
                                                              router ospf 100
                                                               log adjacency changes
                                                               router-id 11.11.11.12
                                                               area 0
                                                                interface Loopback0
                                                                !
                                                                interface POS0/2/0/0
                                                                !
                                                               !
                                                              !
                                                              mpls ldp
                                                               log
                                                                adjacency
                                                                neighbor
                                                               !
                                                               router-id 11.11.11.12
                                                               address-family ipv4
                                                               !
                                                               interface POS0/2/0/0
                                                                address-family ipv4
                                                                !
                                                               !
                                                              !
                                                              no interface POS0/2/0/0 shut
                                                              end
                                                              
                                                              
                                                              CSC-CE13 Configuration
                                                              
                                                              hostname ce13
                                                              
                                                              interface Loopback0
                                                               ipv4 address 11.11.11.11 255.255.255.255
                                                              !
                                                              interface POS0/2/0/0
                                                               ipv4 address 192.170.1.12 255.255.255.0
                                                              !
                                                              router ospf 100
                                                               log adjacency changes
                                                               router-id 11.11.11.11
                                                               area 0
                                                                interface Loopback0
                                                                !
                                                                interface POS0/2/0/0
                                                                !
                                                               !
                                                              !
                                                              mpls ldp
                                                               log
                                                                adjacency
                                                                neighbor
                                                               !
                                                               router-id 11.11.11.11
                                                               address-family ipv4
                                                               !
                                                               interface POS0/2/0/0
                                                                address-family ipv4
                                                                !
                                                               !
                                                              !
                                                              no interface POS0/2/0/0 shut
                                                              end
                                                              
                                                              
                                                              CSC-CE21 Configuration
                                                              
                                                              hostname ce21
                                                              
                                                              interface Loopback0
                                                               ipv4 address 21.21.21.21 255.255.255.255
                                                              !
                                                              interface POS0/2/0/0
                                                               ipv4 address 193.168.1.21 255.255.255.0
                                                              !
                                                              interface POS0/2/0/1
                                                               ipv4 address 193.169.1.21 255.255.255.0
                                                              !
                                                              route-policy pass-all
                                                                pass
                                                              end-policy
                                                              !
                                                              router static
                                                               address-family ipv4 unicast
                                                                193.168.1.2/32 POS0/2/0/0
                                                                193.169.1.2/32 POS0/2/0/1
                                                               !
                                                               address-family ipv6 unicast
                                                                1:1:1::1/128 POS0/2/0/0
                                                               !
                                                              !
                                                              router bgp 2
                                                               bgp router-id 21.21.21.21
                                                               address-family ipv4 unicast
                                                                redistribute connected
                                                                allocate-label all
                                                               !
                                                               neighbor 193.168.1.2
                                                                remote-as 100
                                                                address-family ipv4 labeled-unicast
                                                                 route-policy pass-all in
                                                                 route-policy pass-all out
                                                                !
                                                               !
                                                               neighbor 193.169.1.22
                                                                remote-as 100
                                                                address-family ipv4 labeled-unicast
                                                                 route-policy pass-all in
                                                                 route-policy pass-all out
                                                                !
                                                               !
                                                              !
                                                              no interface POS0/2/0/0 shut
                                                              no interface POS0/2/0/1 shut
                                                              end
                                                              
                                                              
                                                              CSC-PE1 Configuration
                                                              
                                                              hostname pe1
                                                              
                                                              vrf red
                                                               address-family ipv4 unicast
                                                                import route-target
                                                                 100:1
                                                                !
                                                                export route-target
                                                                 100:1
                                                                !
                                                               !
                                                              !
                                                              vrf blue
                                                               address-family ipv4 unicast
                                                               !
                                                              !
                                                              interface Loopback0
                                                               ipv4 address 1.1.1.1 255.255.255.255
                                                               ipv6 address 1:1:1::1/128
                                                              !
                                                              interface Loopback1
                                                               vrf red
                                                               ipv4 address 1.1.1.1 255.255.255.255
                                                              !
                                                              interface Loopback2
                                                               vrf blue
                                                               ipv4 address 1.1.1.1 255.255.255.255
                                                              !
                                                              interface Loopback11
                                                               ipv4 address 1.1.1.2 255.255.255.255
                                                               ipv6 address 1:1:1::2/128
                                                              !
                                                              interface Loopback112
                                                               vrf blue
                                                               ipv4 address 1.1.1.112 255.255.255.255
                                                              !
                                                              interface POS0/2/0/0
                                                               vrf red
                                                               ipv4 address 192.168.1.1 255.255.255.0
                                                              !
                                                              interface POS0/2/0/1
                                                               vrf red
                                                               ipv4 address 192.168.2.1 255.255.255.0
                                                              !
                                                              interface POS0/2/0/2
                                                               vrf blue
                                                               ipv4 address 192.169.1.1 255.255.255.0
                                                              !
                                                              interface POS0/2/0/3
                                                               vrf blue
                                                               ipv4 address 192.170.1.1 255.255.255.0
                                                              !
                                                              interface POS0/2/0/4
                                                               ipv4 address 12.1.0.1 255.255.255.0
                                                               ipv6 address 12:1::1/120
                                                              !
                                                              interface POS0/2/0/5
                                                               ipv4 address 122.1.0.1 255.255.255.0
                                                              !
                                                              router static
                                                               address-family ipv6 unicast
                                                                2:2:2::2/128 POS0/2/0/4
                                                               !
                                                              !
                                                              router ospf 100
                                                               log adjacency changes
                                                               router-id 1.1.1.1
                                                               area 0
                                                                interface Loopback0
                                                                !
                                                                interface POS0/2/0/4
                                                                !
                                                                interface POS0/2/0/5
                                                                !
                                                               !
                                                               vrf red
                                                                router-id 1.1.1.1
                                                                redistribute bgp 100
                                                                area 0
                                                                 interface Loopback1
                                                                 !
                                                                 interface POS0/2/0/0
                                                                 !
                                                                 interface POS0/2/0/1
                                                                 !
                                                                !
                                                               !
                                                               vrf blue
                                                                router-id 1.1.1.1
                                                                area 0
                                                                 interface Loopback2
                                                                 !
                                                                 interface POS0/2/0/2
                                                                 !
                                                                 interface POS0/2/0/3
                                                                 !
                                                                !
                                                               !
                                                              !
                                                              router bgp 100
                                                               address-family ipv4 unicast
                                                               !
                                                               address-family vpnv4 unicast
                                                               !
                                                               neighbor 2.2.2.2
                                                                remote-as 100
                                                                update-source Loopback0
                                                                address-family vpnv4 unicast
                                                                !
                                                               !
                                                               neighbor 2.2.2.22
                                                                remote-as 100
                                                                update-source Loopback0
                                                                address-family vpnv4 unicast
                                                                !
                                                               !
                                                               vrf red
                                                                rd 1:1
                                                                address-family ipv4 unicast
                                                                 maximum-paths eibgp 8
                                                                 redistribute ospf 100
                                                                !
                                                               !
                                                              !
                                                              mpls ldp
                                                               log
                                                                adjacency
                                                                neighbor
                                                               !
                                                               nsr
                                                               router-id 1.1.1.1
                                                               address-family ipv4
                                                                label
                                                                 local
                                                                  advertise
                                                                   explicit-null
                                                                  !
                                                                 !
                                                                !
                                                               !
                                                               interface POS0/2/0/4
                                                                address-family ipv4
                                                                !
                                                               !
                                                               interface POS0/2/0/5
                                                                address-family ipv4
                                                                !
                                                               !
                                                               vrf red
                                                                address-family ipv4
                                                                !
                                                                interface POS0/2/0/0
                                                                 address-family ipv4
                                                                 !
                                                                !
                                                                interface POS0/2/0/1
                                                                 address-family ipv4
                                                                 !
                                                                !
                                                               !
                                                               vrf blue
                                                                router-id 1.1.1.2
                                                                address-family ipv4
                                                                 discovery transport-address 1.1.1.1
                                                                 label
                                                                  local
                                                                   allocate for host-routes
                                                                  !
                                                                 !
                                                                !
                                                                interface POS0/2/0/2
                                                                 address-family ipv4
                                                                 !
                                                                !
                                                                interface POS0/2/0/3
                                                                 address-family ipv4
                                                                 !
                                                                !
                                                               !
                                                              !
                                                              no interface POS0/2/0/0 shut
                                                              no interface POS0/2/0/1 shut
                                                              no interface POS0/2/0/2 shut
                                                              no interface POS0/2/0/3 shut
                                                              no interface POS0/2/0/4 shut
                                                              no interface POS0/2/0/5 shut
                                                              end
                                                              
                                                              
                                                              CSC-PE2 Configuration
                                                              
                                                              hostname pe2
                                                              
                                                              vrf red
                                                               address-family ipv4 unicast
                                                                import route-target
                                                                 100:1
                                                                !
                                                                export route-target
                                                                 100:1
                                                                !
                                                               !
                                                              !
                                                              interface Loopback0
                                                               ipv4 address 2.2.2.2 255.255.255.255
                                                               ipv6 address 2:2:2::2/128
                                                              !
                                                              interface Loopback1
                                                               vrf red
                                                               ipv4 address 2.2.2.2 255.255.255.255
                                                              !
                                                              interface POS0/2/0/0
                                                               ipv4 address 12.1.0.2 255.255.255.0
                                                               ipv6 address 12:1::2/120
                                                              !
                                                              interface POS0/2/0/1
                                                               vrf red
                                                               ipv4 address 193.168.1.2 255.255.255.0
                                                              !
                                                              route-policy pass-all
                                                                pass
                                                              end-policy
                                                              !
                                                              router static
                                                               address-family ipv6 unicast
                                                                1:1:1::1/128 POS0/2/0/0
                                                                1:1:1::2/128 POS0/2/0/0
                                                               !
                                                               vrf red
                                                                address-family ipv4 unicast
                                                                 193.168.1.21/32 POS0/2/0/1
                                                                !
                                                               !
                                                              !
                                                              router ospf 100
                                                               log adjacency changes
                                                               router-id 2.2.2.2
                                                               area 0
                                                                interface Loopback0
                                                                !
                                                                interface POS0/2/0/0
                                                                !
                                                               !
                                                              !
                                                              router bgp 100
                                                               address-family ipv4 unicast
                                                               !
                                                               address-family vpnv4 unicast
                                                               !
                                                               neighbor 1.1.1.1
                                                                remote-as 100
                                                                update-source Loopback0
                                                                address-family vpnv4 unicast
                                                                !
                                                               !
                                                               vrf red
                                                                rd 1:1
                                                                address-family ipv4 unicast
                                                                 allocate-label all
                                                                !
                                                                neighbor 193.168.1.21
                                                                 remote-as 2
                                                                 address-family ipv4 labeled-unicast
                                                                  route-policy pass-all in
                                                                  route-policy pass-all out
                                                                 !
                                                                !
                                                               !
                                                              !
                                                              mpls ldp
                                                               log
                                                                adjacency
                                                                neighbor
                                                               !
                                                               router-id 2.2.2.2
                                                               address-family ipv4
                                                                label
                                                                 local
                                                                  advertise
                                                                   explicit-null
                                                                  !
                                                                 !
                                                                !
                                                               !
                                                               interface POS0/2/0/0
                                                                address-family ipv4
                                                                !
                                                               !
                                                              !
                                                              no interface POS0/2/0/0 shut
                                                              no interface POS0/2/0/1 shut
                                                              end
                                                              
                                                              
                                                              CSC-PE11 Configuration
                                                              
                                                              hostname pe11
                                                              
                                                              vrf red
                                                               address-family ipv4 unicast
                                                                import route-target
                                                                 100:1
                                                                !
                                                                export route-target
                                                                 100:1
                                                                !
                                                               !
                                                              !
                                                              interface Loopback0
                                                               ipv4 address 1.1.1.11 255.255.255.255
                                                              !
                                                              interface Loopback1
                                                               vrf red
                                                               ipv4 address 1.1.1.11 255.255.255.255
                                                              !
                                                              interface POS0/2/0/0
                                                               vrf red
                                                               ipv4 address 192.168.3.1 255.255.255.0
                                                              !
                                                              interface POS0/2/0/1
                                                               ipv4 address 112.1.0.1 255.255.255.0
                                                              !
                                                              router ospf 100
                                                               log adjacency changes
                                                               router-id 1.1.1.11
                                                               area 0
                                                                interface Loopback0
                                                                !
                                                                interface POS0/2/0/1
                                                                !
                                                               !
                                                               vrf red
                                                                router-id 1.1.1.11
                                                                redistribute bgp 100
                                                                area 0
                                                                 interface Loopback1
                                                                 !
                                                                 interface POS0/2/0/0
                                                                 !
                                                                !
                                                               !
                                                              !
                                                              router bgp 100
                                                               address-family ipv4 unicast
                                                               !
                                                               address-family vpnv4 unicast
                                                               !
                                                               neighbor 2.2.2.22
                                                                remote-as 100
                                                                update-source Loopback0
                                                                address-family vpnv4 unicast
                                                                !
                                                               !
                                                               vrf red
                                                                rd 1:1
                                                                address-family ipv4 unicast
                                                                 maximum-paths eibgp 8
                                                                 redistribute ospf 100
                                                                !
                                                               !
                                                              !
                                                              mpls ldp
                                                               log
                                                                adjacency
                                                                neighbor
                                                               !
                                                               router-id 1.1.1.11
                                                               address-family ipv4
                                                               !
                                                               interface POS0/2/0/1
                                                                address-family ipv4
                                                                !
                                                               !
                                                               vrf red
                                                                address-family ipv4
                                                                !
                                                                interface POS0/2/0/0
                                                                 address-family ipv4
                                                                 !
                                                                !
                                                               !
                                                              !
                                                              no interface POS0/2/0/0 shut
                                                              no interface POS0/2/0/1 shut
                                                              end
                                                              
                                                              
                                                              CSC-PE22 Configuration
                                                              
                                                              hostname pe22
                                                              
                                                              vrf red
                                                               address-family ipv4 unicast
                                                                import route-target
                                                                 100:1
                                                                !
                                                                export route-target
                                                                 100:1
                                                                !
                                                               !
                                                              !
                                                              interface Loopback0
                                                               ipv4 address 2.2.2.22 255.255.255.255
                                                              !
                                                              interface Loopback1
                                                               vrf red
                                                               ipv4 address 2.2.2.22 255.255.255.255
                                                              !
                                                              interface POS0/2/0/0
                                                               ipv4 address 122.1.0.22 255.255.255.0
                                                              !
                                                              interface POS0/2/0/1
                                                               vrf red
                                                               ipv4 address 193.169.1.22 255.255.255.0
                                                              !
                                                              interface POS0/2/0/2
                                                               ipv4 address 112.1.0.22 255.255.255.0
                                                              !
                                                              route-policy pass-all
                                                                pass
                                                              end-policy
                                                              !
                                                              router static
                                                               vrf red
                                                                address-family ipv4 unicast
                                                                 193.169.1.21/32 POS0/2/0/1
                                                                !
                                                               !
                                                              !
                                                              router ospf 100
                                                               log adjacency changes
                                                               router-id 2.2.2.22
                                                               area 0
                                                                interface Loopback0
                                                                !
                                                                interface POS0/2/0/0
                                                                !
                                                                interface POS0/2/0/2
                                                                !
                                                               !
                                                              !
                                                              router bgp 100
                                                               address-family ipv4 unicast
                                                               !
                                                               address-family vpnv4 unicast
                                                               !
                                                               neighbor 1.1.1.1
                                                                remote-as 100
                                                                update-source Loopback0
                                                                address-family vpnv4 unicast
                                                                !
                                                               !
                                                               neighbor 1.1.1.11
                                                                remote-as 100
                                                                update-source Loopback0
                                                                address-family vpnv4 unicast
                                                                !
                                                               !
                                                               vrf red
                                                                rd 1:1
                                                                address-family ipv4 unicast
                                                                 allocate-label all
                                                                !
                                                                neighbor 193.169.1.21
                                                                 remote-as 2
                                                                 address-family ipv4 labeled-unicast
                                                                  route-policy pass-all in
                                                                  route-policy pass-all out
                                                                 !
                                                                !
                                                               !
                                                              !
                                                              mpls ldp
                                                               router-id 2.2.2.22
                                                               address-family ipv4
                                                               !
                                                               interface POS0/2/0/0
                                                                address-family ipv4
                                                                !
                                                               !
                                                               interface POS0/2/0/2
                                                                address-family ipv4
                                                                !
                                                               !
                                                              !
                                                              no interface POS0/2/0/0 shut
                                                              no interface POS0/2/0/1 shut
                                                              no interface POS0/2/0/2 shut
                                                              end
                                                              
                                                              
                                                              The following example shows the output for the show running-config mpls ldp command.
                                                              
                                                              RP/0/RSP0/CPU0:router# show running-config mpls ldp
                                                              
                                                              mpls ldp
                                                               log
                                                                adjacency
                                                                neighbor
                                                                nsr
                                                                graceful-restart
                                                                session-protection
                                                               !
                                                               nsr
                                                               graceful-restart
                                                               graceful-restart reconnect-timeout 60
                                                               graceful-restart forwarding-state-holdtime 180
                                                               igp sync delay on-proc-restart 300
                                                               igp sync delay on-session-up 15
                                                               discovery
                                                                quick-start disable
                                                                instance-tlv disable
                                                                hello holdtime 30
                                                                hello interval 10
                                                                targeted-hello holdtime 180
                                                                targeted-hello interval 20
                                                               !
                                                               session backoff 5 15
                                                               session holdtime 300
                                                               signalling dscp 48
                                                               mldp
                                                                logging notifications
                                                                address-family ipv4
                                                                 static p2mp 1.1.1.1 1
                                                                 static mp2mp 10.10.10.10 1
                                                                 make-before-break delay 10
                                                                 mofrr
                                                                 recursive-fec
                                                                !
                                                               !
                                                               router-id 1.1.1.1
                                                               neighbor
                                                                password encrypted 01100F17580454
                                                                2.2.2.2:0 password disable
                                                                3.3.3.3:0 password encrypted 02050D480809
                                                               !
                                                               session downstream-on-demand with peer_acl1
                                                               session protection for peer_acl2 duration 30
                                                               address-family ipv4
                                                                discovery targeted-hello accept from peer_acl1
                                                                neighbor 2.2.2.2 targeted
                                                                traffic-eng
                                                                 auto-tunnel mesh
                                                                  group all
                                                                  group 10
                                                                  group 20
                                                                 !
                                                                !
                                                                redistribute
                                                                 bgp
                                                                  as 100
                                                                  advertise-to peer_acl1
                                                                 !
                                                                !
                                                                label
                                                                 local
                                                                  default-route
                                                                  implicit-null-override for pfx_acl1
                                                                  allocate for pfx_acl
                                                                  advertise
                                                                   disable
                                                                   for pfx_acl1 to peer_acl1
                                                                   for pfx_acl2 to peer_acl2
                                                                   interface GigabitEthernet0/0/0/0
                                                                   explicit-null for pfx_acl1 to peer_acl1
                                                                  !
                                                                 !
                                                                 remote
                                                                  accept
                                                                   from 2.2.2.2:0 for pfx_acl2
                                                                   from 3.3.3.3:0 for pfx_acl3
                                                                  !
                                                                 !
                                                                !
                                                               !
                                                               interface GigabitEthernet0/0/0/0
                                                                igp sync delay on-session-up disable
                                                                discovery quick-start disable
                                                                discovery hello holdtime 30
                                                                discovery hello interval 10
                                                                address-family ipv4
                                                                 igp auto-config disable
                                                                 discovery transport-address interface
                                                                 mldp disable
                                                                !
                                                               !
                                                               interface GigabitEthernet0/0/0/1
                                                                igp sync delay on-session-up 10
                                                                address-family ipv4
                                                                 discovery transport-address 1.1.1.1
                                                                !
                                                               !
                                                               interface GigabitEthernet0/0/0/2
                                                               !
                                                              !
                                                              
                                                              

                                                              Additional References

                                                              For additional information related to Implementing MPLS Label Distribution Protocol, refer to the following references:

                                                              Related Documents

                                                              Related Topic

                                                              Document Title

                                                              LDP Commands

                                                              MPLS Label Distribution Protocol Commands module in Cisco IOS XR MPLS Command Reference for the Cisco CRS Router.

                                                              Standards

                                                              Standards

                                                              Title

                                                              No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

                                                              MIBs

                                                              MIBs

                                                              MIBs Link

                                                              To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http:/​/​cisco.com/​public/​sw-center/​netmgmt/​cmtk/​mibs.shtml

                                                              RFCs

                                                              RFCs
                                                              Note   

                                                              Not all supported RFCs are listed.

                                                              Title

                                                              RFC 3031

                                                              Multiprotocol Label Switching Architecture

                                                              RFC 3036

                                                              LDP Specification

                                                              RFC 3037

                                                              LDP Applicability

                                                              RFC 3478

                                                              Graceful Restart Mechanism for Label Distribution Protocol

                                                              RFC 3815

                                                              Definitions of Managed Objects for MPLS LDP

                                                              RFC 5036

                                                              Label Distribution and Management

                                                              Downstream on Demand Label Advertisement

                                                              RFC 5286

                                                              Basic Specification for IP Fast Reroute: Loop-Free Alternates

                                                              Technical Assistance

                                                              Description

                                                              Link

                                                              The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

                                                              http:/​/​www.cisco.com/​techsupport

                                                              1 For L3VPN Inter-AS option C, LDP may also be required to assign local labels for some BGP prefixes.