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Cisco IOS Software Releases 12.0 S

MPLS LDP Graceful Restart

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Table Of Contents

MPLS LDP Graceful Restart

Contents

Information About MPLS LDP Graceful Restart

How MPLS LDP Graceful Restart Works

How a Route Processor Advertises That It Supports MPLS LDP Graceful Restart

What Happens If a Route Processor Does Not Have LDP Graceful Restart

How to Configure MPLS LDP Graceful Restart

Configuring MPLS LDP Graceful Restart

Restrictions

Verifying the Configuration

Configuration Example for MPLS LDP Graceful Restart

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

debug mpls ldp graceful-restart

mpls ldp graceful-restart

mpls ldp graceful-restart timers max-recovery

mpls ldp graceful-restart timers neighbor-liveness

show mpls ip binding

show mpls ldp bindings

show mpls ldp graceful-restart

show mpls ldp neighbor


MPLS LDP Graceful Restart

When a router is configured with Multiprotocol Label Switching (MPLS) Label Distribution Protocol (LDP) Graceful Restart (GR), it assists a neighboring router that has MPLS LDP Stateful Switchover/Nonstop Forwarding (SSO/NSF) Support and Graceful Restart to recover gracefully from an interruption in service. In this Cisco IOS release, MPLS LDP GR functions strictly in helper mode, which means it can only help other routers that are enabled with MPLS SSO/NSF and GR to recover. If the router with LDP GR fails, its peer routers cannot help it recover.

Notes:

•MPLS LDP SSO/NSF Support and Graceful Restart is supported in Cisco IOS Release 12.2(25)S. For brevity, this feature is called LDP SSO/NSF in this document.

•The MPLS LDP GR feature described in this document refers to helper mode.

When you enable MPLS LDP GR on a router that peers with an MPLS LDP SSO/NSF-enabled router, the SSO/NSF-enabled router can maintain its forwarding state when the LDP session between them is interrupted. While the SSO/NSF-enabled router recovers, the peer router forwards packets using stale information. This enables the SSO/NSF-enabled router to become operational more quickly.

Feature History for MPLS LDP Graceful Restart

Release
Modification

12.0(29)S

The MPLS LDP Graceful Restart feature (in helper mode) was introduced.

12.3(14)T

This feature was integrated into Cisco IOS Release 12.3(14)T.

12.2(33)SRA

This feature was integrated into Cisco IOS Release 12.2(33)SRA.


Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

Contents

•Information About MPLS LDP Graceful Restart

•How to Configure MPLS LDP Graceful Restart

•Configuration Example for MPLS LDP Graceful Restart

•Additional References

•Command Reference

Information About MPLS LDP Graceful Restart

To configure MPLS LDP GR, you need to understand the following concepts:

•How MPLS LDP Graceful Restart Works

•How a Route Processor Advertises That It Supports MPLS LDP Graceful Restart

•What Happens If a Route Processor Does Not Have LDP Graceful Restart

How MPLS LDP Graceful Restart Works

MPLS LDP GR works in strict helper mode, which means it helps a neighboring route processor that has MPLS LDP SSO/NSF to recover from disruption in service without losing its MPLS forwarding state. The disruption in service could be the result of a TCP or UDP event or the stateful switchover of a route processor. When the neighboring router establishes a new session, the LDP bindings and MPLS forwarding states are recovered.

In the topology shown in Figure 1, the following elements have been configured:

•LDP sessions are established between Router 1 and Router 2, as well as between Router 2 and Router 3.

•Router 2 has been configured with MPLS LDP SSO/NSF. Routers 1 and 3 have been configured with MPLS LDP GR.

•A label switched path (LSP) has been established between Router 1 and Router 3.

Figure 1 Example of a Network Using LDP Graceful Restart

The following process shows how Routers 1 and 3, which have been configured with LDP GR help Router 2, which has been configured with LDP SSO/NSF recover from a disruption in service:

1. Router 1 notices an interruption in service with Router 2. (Router 3 also performs the same actions in this process.)

2. Router 1 marks all the label bindings from Router 2 as stale, but it continues to use the bindings for MPLS forwarding.

Router 1 reestablishes an LDP session with Router 2, but keeps its stale label bindings. If you issue a show mpls ldp neighbor command with the graceful-restart keyword, the command output displays the recovering LDP sessions.

3. Both routers readvertise their label binding information. If Router 1 relearns a label from Router 2 after the session has been established, the stale flags are removed. The show mpls forwarding-table command displays the information in the MPLS forwarding table, including the local label, outgoing label or VC, prefix, label-switched bytes, outgoing interface, and next hop.

You can set various graceful restart timers. See the following commands for more information:

•mpls ldp graceful-restart timers neighbor-liveness

•mpls ldp graceful-restart timers max-recovery

How a Route Processor Advertises That It Supports MPLS LDP Graceful Restart

A route processor that is configured to perform MPLS LDP GR includes the Fault Tolerant (FT) Type Length Value (TLV) in the LDP initialization message. The route processor sends the LDP initialization message to a neighbor to establish an LDP session.

The FT session TLV includes the following information:

•The Learn from Network (L) flag is set to 1, which indicates that the route processor is configured to perform MPLS LDP GR.

•The Reconnect Timeout field shows the time (in milliseconds) that the neighbor should wait for a reconnection if the LDP session is lost. In this release, the timer is set to 0, which indicates that if the local router fails, its peers should not wait for it to recover. The timer setting indicates that the local router is working in helper mode.

•The Recovery Time field shows the time (in milliseconds) that the neighbor should retain the MPLS forwarding state during a recovery. If a neighbor did not preserve the MPLS forwarding state before the restart of the control plane, the neighbor sets the recovery time to 0.

What Happens If a Route Processor Does Not Have LDP Graceful Restart

If two route processors establish an LDP session and one route processor is not configured for MPLS LDP GR, the two route processors create a normal LDP session but do not have the ability to perform MPLS LDP GR. Both route processors must be configured for MPLS LDP GR.

How to Configure MPLS LDP Graceful Restart

This section contains the following procedures:

•Configuring MPLS LDP Graceful Restart (required)

•Verifying the Configuration (optional)

Configuring MPLS LDP Graceful Restart

You must enable MPLS LDP GR on all route processors for an LDP session to be preserved during an interruption in service.

MPLS LDP GR is enabled globally. When you enable MPLS LDP GR, it has no effect on existing LDP sessions. New LDP sessions that are established can perform MPLS LDP GR.

Restrictions

•MPLS LDP GR is supported in strict helper mode.

•Tag Distribution Protocol (TDP) sessions are not supported. Only LDP sessions are supported.

•MPLS LDP GR cannot be configured on label-controlled ATM (LC-ATM) interfaces.

•MPLS LDP SSO/NSF is supported in IOS Release 12.2(25)S. It is not supported in this release.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip cef [distributed]

4. mpls ldp graceful-restart

5. interface type slot/port

6. mpls ip

7. mpls label protocol {ldp | tdp | both}

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ip cef [distributed]

Example:

Router(config)# ip cef distributed

Enables Cisco Express Forwarding (CEF).

Step 4  

mpls ldp graceful-restart
Example: 
Router(config)# mpls ldp graceful-restart

Enables the router to protect the LDP bindings and MPLS forwarding state during a disruption in service.

Step 5  

interface type slot/port
Example: 
Router(config)# interface pos 3/0

Specifies an interface and enters interface configuration mode.

Step 6  

mpls ip
Example:

Router(config-if)# mpls ip

Configures MPLS hop-by-hop forwarding for an interface.

Step 7  

mpls label protocol {ldp | tdp | both}
Example:

Router(config-if)# mpls label protocol ldp

Configures the use of LDP for an interface. You must use LDP.


Note You can also issue the mpls label protocol ldp command in global configuration mode, which enables LDP on all interfaces configured for MPLS.

Verifying the Configuration

The following commands help verify that MPLS LDP GR has been configured correctly:

show mpls ldp neighbor with the graceful-restart keyword

Displays the Graceful Restart information for LDP sessions.

show mpls ldp graceful-restart

Displays Graceful Restart sessions and session parameters.


Configuration Example for MPLS LDP Graceful Restart

Figure 2 shows a configuration where MPLS LDP GR is enabled on Router 1 and MPLS LDP SSO/NSF is enabled on Routers 2 and 3. In this configuration example, Router 1 creates an LDP session with Router 2. Router 1 also creates a targeted session with Router 3 through a traffic engineering tunnel using Router 2.

Note MPLS LDP SSO/NSF is supported in Cisco IOS Release 12.2(25)S. It is not supported in this release.

Figure 2 MPLS LDP Graceful Restart Configuration Example

Router 1 configured with LDP GR: 

boot system slot0:rsp-pv-mz 

hw-module slot 2 image slot0:rsp-pv-mz 

hw-module slot 3 image slot0:rsp-pv-mz  

!

ip subnet-zero

ip cef

mpls label range 16 10000 static 10001 1048575

mpls label protocol ldp

mpls ldp logging neighbor-changes

mpls ldp graceful-restart

mpls traffic-eng tunnels

no mpls traffic-eng auto-bw timers frequency 0

mpls ldp router-id Loopback0 force

!

interface Loopback0

 ip address 20.20.20.20 255.255.255.255

 no ip directed-broadcast

 no ip mroute-cache

!

interface Tunnel1

 ip unnumbered Loopback0

 no ip directed-broadcast

 mpls label protocol ldp

 mpls ip

 tunnel destination 19.19.19.19

 tunnel mode mpls traffic-eng

 tunnel mpls traffic-eng autoroute announce

 tunnel mpls traffic-eng priority 7 7

 tunnel mpls traffic-eng bandwidth  500

 tunnel mpls traffic-eng path-option 1 dynamic

!

interface ATM5/1/0

 no ip address

 no ip directed-broadcast

 atm clock INTERNAL

 no atm enable-ilmi-trap

 no atm ilmi-keepalive

!

interface ATM5/1/0.5 point-to-point

 ip address 12.0.0.2 255.0.0.0

 no ip directed-broadcast

 no atm enable-ilmi-trap

 pvc 6/100 

  encapsulation aal5snap

mpls label protocol ldp

mpls traffic-eng tunnels

mpls ip

ip rsvp bandwidth 1000

!

router ospf 100

 log-adjacency-changes

 redistribute connected

     network 12.0.0.0 0.255.255.255 area 100

 network 20.20.20.20 0.0.0.0 area 100

 mpls traffic-eng router-id Loopback0

 mpls traffic-eng area 100

Router 2 configured with LDP SSO/NSF: 

boot system slot0:rsp-pv-mz 

hw-module slot 2 image slot0:rsp-pv-mz 

hw-module slot 3 image slot0:rsp-pv-mz  

!

redundancy

  mode sso

!

ip cef

no ip domain-lookup

mpls label range 17 10000 static 10001 1048575

mpls label protocol ldp

mpls ldp logging neighbor-changes

mpls ldp graceful-restart

mpls traffic-eng tunnels

no mpls traffic-eng auto-bw timers frequency 0

no mpls advertise-labels

mpls ldp router-id Loopback0 force

!

interface Loopback0

 ip address 17.17.17.17 255.255.255.255

 no ip directed-broadcast

!

interface ATM4/0/0

 no ip address

 no ip directed-broadcast

 no ip mroute-cache

 atm clock INTERNAL

 atm sonet stm-1

 no atm enable-ilmi-trap

 no atm ilmi-keepalive

!

interface ATM4/0/0.5 point-to-point

 ip address 12.0.0.1 255.0.0.0

 no ip directed-broadcast

 no atm enable-ilmi-trap

 pvc 6/100 

  encapsulation aal5snap

mpls label protocol ldp

mpls traffic-eng tunnels

mpls ip

ip rsvp bandwidth 1000

!

interface POS5/1/0

 ip address 11.0.0.1 255.0.0.0

 no ip directed-broadcast

 encapsulation ppp

 mpls label protocol ldp

 mpls traffic-eng tunnels

 mpls ip

 no peer neighbor-route

 clock source internal

 ip rsvp bandwidth 1000

!

router ospf 100

 log-adjacency-changes

 redistribute connected

 nsf enforce global

 network 11.0.0.0 0.255.255.255 area 100

 network 12.0.0.0 0.255.255.255 area 100

 network 17.17.17.17 0.0.0.0 area 100

 mpls traffic-eng router-id Loopback0

 mpls traffic-eng area 100

!

ip classless

Router 3 configured with LDP SSO/NSF: 

boot system slot0:rsp-pv-mz 

hw-module slot 2 image slot0:rsp-pv-mz 

hw-module slot 3 image slot0:rsp-pv-mz  

!

redundancy

  mode sso

!

ip subnet-zero

ip cef

!

no ip finger

no ip domain-lookup

mpls label protocol ldp

mpls ldp neighbor 11.11.11.11 targeted ldp

mpls ldp logging neighbor-changes

mpls ldp graceful-restart

mpls traffic-eng tunnels

no mpls traffic-eng auto-bw timers frequency 0

mpls ldp discovery directed-hello interval 12

mpls ldp discovery directed-hello holdtime 130

mpls ldp discovery directed-hello accept

mpls ldp router-id Loopback0 force

!

interface Loopback0

 ip address 19.19.19.19 255.255.255.255

 no ip directed-broadcast

!

interface POS1/0

 ip address 11.0.0.2 255.0.0.0

 no ip directed-broadcast

 encapsulation ppp

 mpls label protocol ldp

 mpls traffic-eng tunnels

 mpls ip

 no peer neighbor-route

 clock source internal

 ip rsvp bandwidth 1000

!

router ospf 100

 log-adjacency-changes

 redistribute connected

 nsf enforce global

network 11.0.0.0 0.255.255.255 area 100

network 19.19.19.19 0.0.0.0 area 100

mpls traffic-eng router-id Loopback0

 mpls traffic-eng area 100

!

ip classless

Additional References

The following sections provide references related to MPLS LDP GR.

Related Documents

Related Topic
Document Title

MPLS Label Distribution Protocol

MPLS Label Distribution Protocol (LDP)


Standards

Standards
Title

None

—


MIBs

MIBs1
MIBs Link

•MPLS Label Distribution Protocol MIB Version 8 Upgrade

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

1 Not all supported MIBs are listed.


RFCs

RFCs1
Title

RFC 3036

LDP Specification

RFC 3478

Graceful Restart Mechanism for Label Distribution

1 Not all supported RFCs are listed.


Technical Assistance

Description
Link

The Cisco Technical Support & Documentation 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


Command Reference

This section documents modified commands.

New Commands

•debug mpls ldp graceful-restart

•mpls ldp graceful-restart

•mpls ldp graceful-restart timers max-recovery

•mpls ldp graceful-restart timers neighbor-liveness

Modified Commands

•show mpls ip binding

•show mpls ldp bindings

•show mpls ldp graceful-restart

•show mpls ldp neighbor

debug mpls ldp graceful-restart

To display debugging information for Multiprotocol (MPLS) Label Distribution Protocol (LDP) Stateful Switchover (SSO) Nonstop Forwarding (NSF) Support and Graceful Restart, use the debug mpls ldp graceful-restart command in privileged EXEC mode. To disable the display of this debugging information, use the no form of this command.

debug mpls ldp graceful-restart

no debug mpls ldp graceful-restart

Syntax Description

This command has no arguments or keywords.

Defaults

The display of debugging information is not enabled.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.0(29)S

This command was introduced.

12.3(14)T

This command was integrated into Cisco IOS Release 12.3(14)T.

12.2(25)S

This command was introduced.

12.2(28)SB

This command was integrated into Cisco IOS Release 12.2(28)SB and implemented on the Cisco 10000 series routers.

12.2(33)SRA

This command was integrated into Cisco IOS Release 12.2(33)SRA.


Usage Guidelines

This command shows events and errors related to LDP Graceful Restart.

Examples

The following example shows sample output from the debug mpls ldp graceful-restart command. The output shows that a session was lost. The status message show the events that happen during recovery of the bindings. 

Router# debug mpls ldp graceful-restart


LDP GR: GR session 10.110.0.10:0:: lost

LDP GR: down nbr 10.110.0.10:0:: created [1 total]

LDP GR: GR session 10.110.0.10:0:: bindings retained

LDP GR: down nbr 10.110.0.10:0:: added all 7 addresses [7 total]

LDP GR: down nbr 10.110.0.10:0:: state change (None -> Reconnect-Wait)

LDP GR: down nbr 10.110.0.10:0:: reconnect timer started [120000 msecs]

LDP GR: down nbr 10.110.0.10:0:: added to bindings task queue [1 entries]

LDP GR: searching for down nbr record (10.110.0.10:0, 10.2.0.10)

LDP GR: search for down nbr record (10.110.0.10:0, 10.2.0.10) returned 10.110.0.10:0

LDP GR: Added FT Sess TLV (Rconn 120000, Rcov 120000) to INIT msg to 10.110.0.10:0

LDP GR: Tagcon querying for up to 12 bindings update tasks

LDP GR: down nbr 10.110.0.10:0:: requesting bindings MARK for {10.110.0.10:0, 1}

LDP GR: down nbr 10.110.0.10:0:: removed from bindings task queue [0 entries]

LDP GR: Requesting 1 bindings update tasks [0 left in queue]

LDP GR: 10.0.0.0/8:: updating binding from 10.110.0.10:0, inst 1:: marking stale; 

LDP GR: 10.2.0.0/16:: updating binding from 10.110.0.10:0, inst 1:: marking stale; 

LDP GR: 14.0.0.14/32:: updating binding from 10.110.0.10:0, inst 1:: marking stale; 

LDP GR: searching for down nbr record (10.110.0.10:0, 10.2.0.10)

LDP GR: search for down nbr record (10.110.0.10:0, 10.2.0.10) returned 10.110.0.10:0

LDP GR: Added FT Sess TLV (Rconn 120000, Rcov 120000) to INIT msg to 10.110.0.10:0

LDP GR: searching for down nbr record (10.110.0.10:0, 10.2.0.10)

LDP GR: search for down nbr record (10.110.0.10:0, 10.2.0.10) returned 10.110.0.10:0

LDP GR: Added FT Sess TLV (Rconn 120000, Rcov 120000) to INIT msg to 10.110.0.10:0

LDP GR: searching for down nbr record (10.110.0.10:0, 10.2.0.10)

LDP GR: search for down nbr record (10.110.0.10:0, 10.2.0.10) returned 10.110.0.10:0

LDP GR: Added FT Sess TLV (Rconn 120000, Rcov 120000) to INIT msg to 10.110.0.10:0

LDP GR: searching for down nbr record (10.110.0.10:0, 10.2.0.10)

LDP GR: search for down nbr record (10.110.0.10:0, 10.2.0.10) returned 10.110.0.10:0

LDP GR: Added FT Sess TLV (Rconn 120000, Rcov 120000) to INIT msg to 10.110.0.10:0

LDP GR: searching for down nbr record (10.110.0.10:0, 10.2.0.10)

LDP GR: search for down nbr record (10.110.0.10:0, 10.2.0.10) returned 10.110.0.10:0

LDP GR: Added FT Sess TLV (Rconn 120000, Rcov 120000) to INIT msg to 10.110.0.10:0

LDP GR: Received FT Sess TLV from 10.110.0.10:0  (fl 0x1, rs 0x0, rconn 120000, rcov 
120000)

LDP GR: GR session 10.110.0.10:0:: allocated instance, 2

LDP GR: GR session 10.110.0.10:0:: established

LDP GR: GR session 10.110.0.10:0:: found down nbr 10.110.0.10:0

LDP GR: down nbr 10.110.0.10:0:: reconnect timer stopped

LDP GR: down nbr 10.110.0.10:0:: state change (Reconnect-Wait -> Recovering)

LDP GR: down nbr 10.110.0.10:0:: recovery timer started [120000 msecs]

%LDP-5-GR: GR session 10.110.0.10:0 (inst. 2): starting graceful recovery

%LDP-5-NBRCHG: LDP Neighbor 10.110.0.10:0 is UP

LDP GR: 2.0.0.0//8:: refreshing stale binding from 10.110.0.10:0, inst 1 -> inst 2

LDP GR: 10.43.0.0//16:: refreshing stale binding from 10.110.0.10:0, inst 1 -> inst 2

LDP GR: down nbr 10.110.0.10:0:: recovery timer expired

%LDP-5-GR: GR session 10.110.0.10:0 (inst. 2): completed graceful recovery

LDP GR: down nbr 10.110.0.10:0:: destroying record [0 left]

LDP GR: down nbr 10.110.0.10:0:: state change (Recovering -> Delete-Wait)

LDP GR: down nbr 10.110.0.10:0:: added to bindings task queue [1 entries]

LDP GR: Tagcon querying for up to 12 bindings update tasks

LDP GR: down nbr 10.110.0.10:0:: requesting bindings DEL for {10.110.0.10:0, 1}

LDP GR: down nbr 10.110.0.10:0:: removed from bindings task queue [0 entries]

LDP GR: Requesting 1 bindings update tasks [0 left in queue]

LDP GR: GR session 10.110.0.10:0:: released instance, 1

The debug output is formatted in three general ways. Table 1 describes the fields for the debug command output:

Table 1 debug mpls ldp graceful-restart Command Field Descriptions 

Field
Description

LDP GR: GR session 10.110.0.10:0:: found down nbr 10.110.0.10:0

LDP GR

Identifies LDP Graceful Restart application

GR session 10.110.0.10:0

ID of the LDP session that is enabled for Graceful Restart.

found down nbr 10.110.0.10:0

Describes the event that is happening to that LDP session.

LDP GR: down nbr 10.110.0.10:0:: removed from bindings task queue [0 entries]

down nbr 10.110.0.10:0::

Identifies the Down Neighbor record, which logs the state of a recently lost Graceful Restart session.

removed from bindings task queue [0 entries]

Describes the event that is happening to the recently lost Graceful Restart session.

LDP GR: 10.0.0.0/8:: updating binding from 10.110.0.10:0, inst 1:: marking stale;

10.0.0.0/8::

Identifies the Forwarding Equivalence Class (FEC) associated with the remote label binding being modified. The FEC identifies the Label Information Base (LIB) entry.

updating binding

Lists the operation being performed on the remote label binding.

10.110.0.10:0, inst 1:: marking stale;

Identifies the LDP session during which the remote label binding was learned.


:

Related Commands

Command
Description

show mpls ldp graceful-restart

Displays a summary of the LDP Graceful Restart status.


mpls ldp graceful-restart

To enable Multiprotocol Label Switching (MPLS) Label Distribution Protocol (LDP) Graceful Restart, use the mpls ldp graceful-restart command in global configuration mode. To disable LDP Graceful Restart, use the no form of this command.

mpls ldp graceful-restart

no mpls ldp graceful-restart

Syntax Description

This command has no arguments or keywords.

Defaults

LDP Graceful Restart is not enabled.

Command Modes

Global configuration

Command History

Release
Modification

12.0(29)S

This command was introduced.

12.3(14)T

This command was integrated into Cisco IOS Release 12.3(14)T.

12.2(25)S

This command was integrated into Cisco IOS Release 12.2(25)S.

12.2(28)SB

This command was integrated into Cisco IOS Release 12.2(28)SB and implemented on the Cisco 10000 series routers.

12.2(33)SRA

This command was integrated into Cisco IOS Release 12.2(33)SRA.


Usage Guidelines

LDP Graceful Restart must be enabled before an LDP session is established.

Using the no form of the command disables the Graceful Restart functionality on all LDP sessions.

Examples

The command in the following example enables LDP Graceful Restart on a router: 

Router(config)# mpls ldp graceful-restart

Related Commands

Command
Description

mpls ldp graceful-restart timers forwarding-holding

Specifies the amount of time the MPLS forwarding state should be preserved after the control plane restarts.

mpls ldp graceful-restart timers neighbor-liveness

Specifies the amount of time a router should wait for an LDP session to be reestablished.

mpls ldp graceful-restart timers max-recovery

Specifies the amount of time a router should hold stale label-FEC bindings after an LDP session has been reestablished.


mpls ldp graceful-restart timers max-recovery

To specify the amount of time a router should hold stale label-Forwarding Equivalence Class (FEC) bindings after a Label Distribution Protocol (LDP) session has been reestablished, use the mpls ldp graceful-restart timers max-recovery command in global configuration mode. To revert to the default timer value, use the no form of this command.

mpls ldp graceful-restart timers max-recovery secs

no mpls ldp graceful-restart timers max-recovery

Syntax Description

secs

The amount of time (in seconds) that the router should hold stale label-FEC bindings after an LDP session has been reestablished. The default is 120 seconds. The acceptable range of values is 15 to 600 seconds.


Defaults

Stale label-FEC bindings are held for 120 seconds after an LDP session has been reestablished.

Command Modes

Global configuration

Command History

Release
Modification

12.0(29)S

This command was introduced.

12.3(14)T

This command was integrated into Cisco IOS Release 12.3(14)T.

12.2(28)SB

This command was integrated into Cisco IOS Release 12.2(28)SB and implemented on the Cisco 10000 series routers.

12.2(33)SRA

This command was integrated into Cisco IOS Release 12.2(33)SRA.


Usage Guidelines

After the timer expires, all stale label-FEC bindings learned from the associated LDP session are removed, which results in the removal of any forwarding table entries that are based on those bindings.

Examples

In the following example, the router should hold stale label-FEC bindings after an LDP session has been reestablished for 180 seconds: 

Router(config)# mpls ldp graceful-restart timers max-recovery 180

Related Commands

Command
Description

mpls ldp graceful-restart timers forwarding-holding

Specifies the amount of time the MPLS forwarding state should be preserved after the control plane restarts.

mpls ldp graceful-restart timers neighbor-liveness

Specifies the amount of time a router should wait for an LDP session to be reestablished.


mpls ldp graceful-restart timers neighbor-liveness

To specify the upper bound on the amount of time a router should wait for a Label Distribution Protocol (LDP) session to be reestablished, use the mpls ldp graceful-restart timers neighbor-liveness command in global configuration mode. To revert to the default timer value, use the no form of this command.

mpls ldp graceful-restart timers neighbor-liveness secs

no mpls ldp graceful-restart timers neighbor-liveness

Syntax Description

secs

The amount of time (in seconds) that the router should wait for an LDP session to be reestablished. The default is 120 seconds. The range is 5 to 300 seconds.


Defaults

The default is a maximum of 120 seconds.

Command Modes

Global configuration

Command History

Release
Modification

12.0(29)S

This command was introduced.

12.3(14)T

This command was integrated into Cisco IOS Release 12.3(14)T.

12.2(28)SB

This command was integrated into Cisco IOS Release 12.2(28)SB and implemented on the Cisco 10000 series routers.

12.2(33)SRA

This command was integrated into Cisco IOS Release 12.2(33)SRA.


Usage Guidelines

The amount of time a router waits for an LDP session to be reestablished is the lesser of the following values:

•The value of the peers Fault Tolerant (FT) Type Length Value (TLV) Reconnect Timeout

•The value of the neighbor liveness timer

If the router cannot reestablish an LDP session with the neighbor in the time allotted, the router deletes the stale label-FEC bindings received from that neighbor.

Examples

The command in the following example sets the amount of time that the router should wait for an LDP session to be reestablished to 30 seconds: 

Router(config)# mpls ldp graceful-restart timers neighbor-liveness 30

Related Commands

Command
Description

mpls ldp graceful-restart timers forwarding-holding

Specifies the amount of time the MPLS forwarding state should be preserved after the control plane restarts.

mpls ldp graceful-restart timers max-recovery

Specifies the amount of time a router should hold stale label-FEC bindings after an LDP session has been reestablished.


show mpls ip binding

To display specified information about label bindings learned by the Multiprotocol Label Switching (MPLS) Label Distribution Protocol (LDP), use the show mpls ip binding command in user EXEC or privileged EXEC mode.

show mpls ip binding [vrf vrf-name | all] [network {mask | length} [longer-prefixes]]
[neighbor address | local] [local-label {atm vpi vci | label  [- label]}]
[remote-label {atm vpi vci | label  [- label]}] [interface interface] [generic | atm]

show mpls ip binding [vrf vrf-name | all] [detail | summary]

Cisco 10000 Series Routers

show mpls ip binding [network {mask | length} [longer-prefixes]] [neighbor address | local] [local-label label [- label]] [remote-label label  [- label]] [generic]

show mpls ip binding [detail | summary]

Syntax Description

vrf vrf-name

(Optional) Displays the LDP neighbors for the specified Virtual Private Network (VPN) routing and forwarding (VRF) instance (vrf-name).

Note This keyword and argument pair does not apply to the Cisco 10000 series routers.

all

(Optional) Displays binding information for all VRFs.

Note This keyword does not apply to the Cisco 10000 series routers.

network

(Optional) Defines the destination network number.

mask

(Optional) Defines the network mask, written as A.B.C.D.

length

(Optional) Defines the mask length (1 to 32 characters).

longer-prefixes

(Optional) Selects any prefix that matches the mask with a length from 1 to 32 characters.

neighbor address

(Optional) Displays label bindings assigned by the selected neighbor.

local

(Optional) Displays the local label bindings.

local-label atm vpi vci

(Optional) Displays the entry with the locally assigned ATM label that matches the specified ATM label value. The virtual path identifier (VPI) range is 0 to 4095. The virtual channel identifier (VCI) range is 0 to 65535.

Note These keywords and arguments do not apply to the Cisco 10000 series routers.

local-label label - label

(Optional) Displays entries with locally assigned labels that match the specified label values. Use the label - label arguments and keyword to indicate the label range. The hyphen (-) keyword is required for a label range.

remote-label atm vpi vci

(Optional) Displays entries with remotely assigned ATM label values learned from neighbor routers that match the specified ATM label value. The VPI range is 0 to 4095. The VCI range is 0 to 65535.

Note These keywords and arguments do not apply to the Cisco 10000 series routers.

remote-label label - label

(Optional) Displays entries with remotely assigned labels learned from neighbor routers that match the specified label values. Use the label - label arguments and keyword to indicate the label range. The hyphen (-) keyword is required for a label range.

interface interface

(Optional) Displays label bindings associated with the specified interface (for label-controlled (LC)-ATM only).

Note This keyword and argument pair does not apply to the Cisco 10000 series routers.

generic

(Optional) Displays only generic (non-LC-ATM) label bindings.

atm

(Optional) Displays only LC-ATM label bindings.

Note This keyword does not apply to the Cisco 10000 series routers.

detail

(Optional) Displays detailed information about label bindings learned by LDP.

summary

(Optional) Displays summary information about label bindings learned by LDP.


Defaults

All label bindings are displayed when no optional arguments or keywords are specified.

Command Modes

User EXEC
Privileged EXEC

Command History

Release
Modification

12.0(10)ST

This command was introduced.

12.0(14)ST

This command was modified to reflect MPLS VPN support for LDP.

12.1(2)T

This command was integrated into Cisco IOS Release 12.1(2)T.

12.1(8a)E

This command was integrated into Cisco IOS Release 12.1(8a)E.

12.2(2)T

This command was integrated into Cisco IOS Release 12.2(2)T.

12.2(4)T

The VPI range of values was extended to 4095.


12.2(8)T

This command was integrated into Cisco IOS Release 12.2(8)T.

12.0(21)ST

This command was integrated into Cisco IOS Release 12.0(21)ST.

12.0(22)S

This command was integrated into Cisco IOS Release 12.0(22)S.

12.0(23)S

This command was integrated into Cisco IOS Release 12.0(23)S.

12.2(13)T

This command was integrated into Cisco IOS Release 12.2(13)T.

12.2(14)S

This command was integrated into Cisco IOS Release 12.2(14)S.

12.2(25)S

The detail keyword was added to display checkpoint status for local label bindings.

12.2(28)SB

This command was integrated into Cisco IOS Release 12.2(28)SB and implemented on the Cisco 10000 series routers.

12.2(33)SRA

This command was integrated into Cisco IOS Release 12.2(33)SRA.


Usage Guidelines

The show mpls ip binding command displays label bindings learned by LDP or the Tag Distribution Protocol (TDP).

Note TDP is not supported for LDP features in Cisco IOS 12.0(30)S and later releases, 12.2(27)SBC and later 12.2S releases, and 12.3(14)T and later releases.

To summarize information about label bindings learned by LDP, use the show mpls ip binding summary command in user EXEC or privileged EXEC mode.

A request can specify that the entire database be displayed, that a summary of entries from the database be displayed, or that the display be limited to a subset of entries. The subset can be limited according to any of the following:

•Prefix

•Input or output label values or ranges

•Neighbor advertising the label

•Interface for label bindings of interest (LC-ATM only)

Note LC-ATM label binding interface does not apply to the Cisco 10000 series routers.

•Generic (non-LC-ATM) label bindings

•LC-ATM label bindings

Note LC-ATM label binding interface does not apply to the Cisco 10000 series routers.

Examples

The following is sample output from the show mpls ip binding command. The output shows all the label bindings in the database. 

Router# show mpls ip binding 


  10.0.0.0/8 

        in label:     20        

        out label:    26        lsr: 10.0.0.55:0    

        out vc label: 1/80      lsr: 10.0.7.7:2      ATM1/0.8

                      Active    ingress 3 hops (vcd 49) 

  172.16.0.0/8 

        in label:     25        

        in vc label:  1/36      lsr: 10.0.7.7:2      ATM1/0.8

                      Active    egress (vcd 55) 

        out label:    imp-null  lsr: 10.0.0.55:0     inuse

  192.168.0.66/32 

        in label:     26        

        in vc label:  1/39      lsr: 10.0.7.7:2      ATM1/0.8

                      Active    egress (vcd 58) 

        out label:    16        lsr: 10.0.0.55:0     inuse

.

.

.

In the following example, a request is made for the display of the label binding information for prefix 192.168.44.0/24: 

Router# show mpls ip binding 192.168.44.0 24


  192.168.44.0/24 

        in label:     24        

        in vc label:  1/37      lsr: 10.0.7.7:2      ATM1/0.8

                      Active    egress (vcd 56) 

        out label:    imp-null  lsr: 10.0.0.55:0     inuse

Router#

In the following example, the local-label keyword is used to request that label binding information be displayed for the prefix with local label 58: 

Router# show mpls ip binding local-label 58


  192.168.0.0/16 

        in label:     58        

        out label:    imp-null  lsr: 10.0.0.55:0     inuse

Router#

The following sample output shows the label bindings for the VPN routing and forwarding instance named vpn1: 

Router# show mpls ip binding vrf vpn1


  10.3.0.0/16 

        in label:    117       

        out label:   imp-null  lsr:10.14.14.14:0   

  10.13.13.13/32 

        in label:    1372      

        out label:   268       lsr:10.14.14.14:0   

  10.14.14.14/32 

        in label:    118       

        out label:   imp-null  lsr:10.14.14.14:0   

  10.15.15.15/32 

        in label:    1370      

        out label:   266       lsr:10.14.14.14:0   

  10.16.16.16/32 

        in label:    8370      

        out label:   319       lsr:10.14.14.14:0   

  10.18.18.18/32 

        in label:    21817     

        out label:   571       lsr:10.14.14.14:0   

  30.2.0.0/16 

        in label:    6943      

        out label:   267       lsr:10.14.14.14:0   

  10.30.3.0/16 

        in label:    2383      

        out label:   imp-null  lsr:10.14.14.14:0   

  10.30.4.0/16 

        in label:    77        

        out label:   imp-null  lsr:10.14.14.14:0   

  10.30.5.0/16 

        in label:    20715     

        out label:   504       lsr:10.14.14.14:0   

  10.30.7.0/16 

        in label:    17        

        out label:   imp-null  lsr:10.14.14.14:0   

  10.30.10.0/16 

        in label:    5016      

        out label:   269       lsr:10.14.14.14:0   

  10.30.13.0/16 

        in label:    76        

        out label:   imp-null  lsr:10.14.14.14:0

The following sample output shows label binding information for all VRFs: 

Router# show mpls ip binding all     


  10.0.0.0/24 

        in label:     imp-null  

        out label:    imp-null  lsr: 10.131.0.1:0     

  10.11.0.0/24 

        in label:     imp-null  

        out label:    imp-null  lsr: 10.131.0.1:0 

  10.101.0.1/32 

        out label:    imp-null  lsr: 10.131.0.1:0 

  10.131.0.1/32 

        in label:     20        

        out label:    imp-null  lsr: 10.131.0.1:0      inuse

  10.134.0.1/32 

        in label:     imp-null  

        out label:    16        lsr: 10.131.0.1:0     

VRF vrf1:

  10.0.0.0/24 

        out label:    imp-null  lsr: 10.132.0.1:0     

  10.11.0.0/24 

        out label:    imp-null  lsr: 10.132.0.1:0     

  10.12.0.0/24 

        in label:     17        

        out label:    imp-null  lsr: 10.132.0.1:0     

  10.132.0.1/32 

        out label:    imp-null  lsr: 10.132.0.1:0     

  10.134.0.2/32 

        in label:     18        

        out label:    16        lsr: 10.132.0.1:0     

  10.134.0.4/32 

        in label:     19        

        out label:    17        lsr: 10.132.0.1:0     

  10.138.0.1/32 

        out label:    imp-null  lsr: 10.132.0.1:0

Cisco 10000 Series Examples Only

The following sample shows binding information for a Cisco 10000 series router: