MPLS LDP Session Protection

Table Of Contents

MPLS LDP Session Protection

Contents

Information About MPLS LDP Session Protection

How to Configure MPLS LDP Session Protection

Enabling MPLS LDP Session Protection

Prerequisites

Restrictions

Customizing MPLS LDP Session Protection

Specifying How Long an LDP Targeted Hello Adjacency Should Be Retained

Specifying Which Routers Should Have MPLS LDP Session Protection

Verifying MPLS LDP Session Protection

Troubleshooting Tips

Configuration Examples for MPLS LDP Session Protection

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

debug mpls ldp session protection

mpls ldp session protection

show mpls ldp neighbor

MPLS LDP Session Protection

---

The MPLS LDP Session Protection feature provides faster label distribution protocol (LDP) convergence when a link recovers following an outage. MPLS LDP Session Protection protects an LDP session between directly connected neighbors or an LDP session established for a Traffic Engineering (TE) tunnel.

Feature History for the MPLS LDP Session Protection

Release	Modification
12.0(30)S	This feature was introduced.
12.3(14)T	This feature was integrated into Cisco IOS Release 12.3(14)T.
12.2(27)SBA	This feature was integrated into Cisco IOS Release 12.2(27)SBA.

Feature

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 Session Protection

•How to Configure MPLS LDP Session Protection

•Configuration Examples for MPLS LDP Session Protection

•Additional References

•Command Reference

Information About MPLS LDP Session Protection

MPLS LDP Session Protection maintains LDP bindings when a link fails. MPLS LDP sessions are protected through the use of LDP Hello messages. When you enable MPLS LDP, the label switched routers (LSRs) send messages to find other LSRs with which they can create LDP sessions.

•If the LSR is one hop from its neighbor, it is directly connected to its neighbor. The LSR sends out LDP Hello messages as User Datagram Protocol (UDP) packets to all the routers on the subnet. The hello message is called an LDP Link Hello. A neighboring LSR responds to the hello message and the two routers begin to establish an LDP session.

•If the LSR is more than one hop from its neighbor, it is not directly connected to its neighbor. The LSR sends out a directed hello message as a UDP packet, but as a unicast message specifically addressed to that LSR. The hello message is called an LDP Targeted Hello. The nondirectly connected LSR responds to the Hello message and the two routers establish an LDP session. (If the path between two LSRs has been traffic engineered and has LDP enabled, the LDP session between them is called a targeted session.)

MPLS LDP Session Protection uses LDP Targeted Hellos to protect LDP sessions. Take, for example, two directly connected routers that have LDP enabled and can reach each other through alternate IP routes in the network. An LDP session that exists between two routers is called an LDP Link Hello Adjacency. When MPLS LDP Session Protection is enabled, an LDP Targeted Hello Adjacency is also established for the LDP session. If the link between the two routers fails, the LDP Link Adjacency also fails. However, if the LDP peer is still reachable through IP, the LDP session stays up, because the LDP Targeted Hello Adjacency still exists between the routers. When the directly connected link recovers, the session does not need to be reestablished, and LDP bindings for prefixes do not need to be relearned.

How to Configure MPLS LDP Session Protection

This section explains how to configure and verify MPLS LDP Session Protection:

•Enabling MPLS LDP Session Protection (required)

•Customizing MPLS LDP Session Protection (optional)

•Verifying MPLS LDP Session Protection (optional)

Enabling MPLS LDP Session Protection

You use the mpls ldp session protection command to enable MPLS LDP Session Protection. This command enables LDP sessions to be protected during a link failure. By default, the command protects all LDP sessions. The command has several options that enable you to specify which LDP sessions to protect. The vrf keyword lets you protect LDP sessions for a specified VRF. The for keyword lets you specify a standard IP access control list (ACL) of prefixes that should be protected. The duration keyword enables you to specify how long the router should retain the LDP Targeted Hello Adjacency following the loss of the LDP Link Hello Adjacency.

Prerequisites

LSRs must be able to respond to LDP targeted hellos. Otherwise, the LSRs cannot establish a targeted adjacency. All routers that participate in MPLS LDP Session Protection must be enabled to respond to targeted hellos. Both neighbor routers must be configured for session protection or one router must be configured for session protection and the other router must be configured to respond to targeted hellos.

Restrictions

This feature is not supported under the following circumstances:

•With TDP sessions

•With extended access lists

•With LC-ATM routers

SUMMARY STEPS

1. enable

2. configure terminal

3. ip cef [distributed]

4. interface loopbacknumber

5. ip address {prefix mask}

6. interface interface

7. mpls ip

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

9. mpls ldp session protection [vrf vpn-name] [for acl] [duration seconds]

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	Configures Cisco Express Forwarding.
Step 4	interface loopbacknumber Example: Router(config)# interface Loopback0	Configures a loopback interface.
Step 5	ip address {prefix mask} Example: Router(config-if)# ip address 131.25.0.11 255.255.255.255	Assigns an IP address to the loopback interface.
Step 6	interface interface Example: Router(config)# interface POS3/0	Specifies the interface to configure.
Step 7	mpls ip Example: Router(config-if)# mpls ip	Configures MPLS hop-by-hop forwarding for a specified interface.
Step 8	mpls label protocol {ldp | tdp | both} Example: Router(config-if)# mpls label protocol ldp or Router(config)# mpls label protocol ldp	Configures the use of LDP on a specific interface or on all interfaces. In interface configuration mode, the command sets the default label distribution protocol for the interface to be LDP, overriding any default set by the global mpls label protocol command. In global configuration mode, the command sets all the interfaces to LDP.
Step 9	mpls ldp session protection [vrf vpn-name] [for acl] [duration seconds] Example: Router(config)# mpls ldp session protection	Enables MPLS LDP Session Protection.

Customizing MPLS LDP Session Protection

You can modify MPLS LDP Session Protection by using the keywords in the mpls ldp session protection command. The following sections explain how to customize the feature.

Specifying How Long an LDP Targeted Hello Adjacency Should Be Retained

The default behavior of the mpls ldp session protection command allows an LDP Targeted Hello Adjacency to exist indefinitely following the loss of an LDP Link Hello Adjacency. You can issue the duration keyword to specify the number of seconds (from 30 to 2,147,483) that the LDP Targeted Hello Adjacency is retained after the loss of the LDP Link Hello Adjacency. When the link is lost, a timer starts. If the timer expires, the LDP Targeted Hello Adjacency is removed.

Specifying Which Routers Should Have MPLS LDP Session Protection

The default behavior of the mpls ldp session protection command allows MPLS LDP Session Protection for all neighbor sessions. You can issue either the vrf or for keyword to limit the number of neighbor sessions that are protected.

Enabling MPLS LDP Session Protection on Specified VPN Routing and Forwarding Instances

If the router is configured with at least one VPN routing and forwarding (VRF) instance, you can use the vrf keyword to select which VRF is to be protected. You cannot specify more than one VRF with the mpls ldp session protection command. To specify multiple VRFs, issue the command multiple times.

Enabling MPLS LDP Session Protection on Specified Peer Routers

You can create an access list that includes several peer routers. You can specify that access list with the for keyword to enable LDP Session Protection for the peer routers in the access control list.

Verifying MPLS LDP Session Protection

To verify that LDP Session Protection has been correctly configured, perform the following steps.

SUMMARY STEPS

1. show mpls ldp discovery

2. show mpls ldp neighbor

3. show mpls ldp neighbor detail

DETAILED STEPS

---

Step 1 show mpls ldp discovery

Issue this command and check that the output contains xmit/recv to the peer router.

Router# show mpls ldp discovery

 Local LDP Identifier:

    16.0.0.5:0

    Discovery Sources:

    Interfaces:

        ATM5/1/0.5 (ldp): xmit/recv

            LDP Id: 16.0.0.1:0

    Targeted Hellos:

        16.0.0.5 -> 16.0.0.3 (ldp): active, xmit/recv

            LDP Id: 16.0.0.3:0

Step 2 show mpls ldp neighbor

Issue this command to check that the targeted hellos are active.

Router# show mpls ldp neighbor 

Peer LDP Ident: 16.0.0.3:0; Local LDP Ident 16.0.0.5:0

TCP connection: 16.0.0.3.646 - 16.0.0.5.11005

State: Oper; Msgs sent/rcvd: 1453/1464; Downstream

Up time: 21:09:56

LDP discovery sources:

 Targeted Hello 16.0.0.5 -> 16.0.0.3, active

Addresses bound to peer LDP Ident:

 3.3.104.3       10.0.0.2        16.0.0.3

Step 3 show mpls ldp neighbor detail

Issue this command to check that the MPLS LDP Session Protection state is Ready or Protecting. If the second last line of the output shows Incomplete, the Targeted Hello Adjacency is not up yet.

Router# show mpls ldp neighbor detail

    Peer LDP Ident: 16.16.16.16:0; Local LDP Ident 15.15.15.15:0

        TCP connection: 16.16.16.16.11013 - 15.15.15.15.646

        State: Oper; Msgs sent/rcvd: 53/51; Downstream; Last TIB rev sent 74

        Up time: 00:11:32; UID: 1; Peer Id 0;

        LDP discovery sources:

          Targeted Hello 15.15.15.15 -> 16.16.16.16, active, passive;

            holdtime: infinite, hello interval: 10000 ms

        Addresses bound to peer LDP Ident:

          10.0.0.2        16.16.16.16     101.101.101.101 11.0.0.1        

        Peer holdtime: 180000 ms; KA interval: 60000 ms; Peer state: estab

        Clients: Dir Adj Client

        LDP Session Protection enabled, state: Protecting

            duration: infinite

---

Troubleshooting Tips

Use the clear mpls ldp neighbor command if you need to terminate an LDP session after a link goes down. This is useful for situations where the link needs to be taken out of service or needs to be connected to a different neighbor.

Configuration Examples for MPLS LDP Session Protection

Figure 1 shows a sample configuration for MPLS LDP Session Protection.

Figure 1 MPLS LDP Session Protection Example

R1

redundancy

 no keepalive-enable

 mode hsa

!

ip cef distributed

no ip domain-lookup

multilink bundle-name both

mpls label protocol ldp

mpls ldp session protection

no mpls traffic-eng auto-bw timers frequency 0

tag-switching tdp router-id Loopback0 force

!

interface Loopback0

 ip address 10.0.0.1 255.255.255.255

 no ip directed-broadcast

 no ip mroute-cache

!

interface Multilink4

 no ip address

 no ip directed-broadcast

 no ip mroute-cache

 load-interval 30

 ppp multilink

 multilink-group 4

!

interface Ethernet1/0/0

 ip address 3.3.123.1 255.255.0.0

 no ip directed-broadcast

!

interface Ethernet4/0/0

 no ip address

 no ip directed-broadcast

 shutdown

!

interface Ethernet4/0/1

 description --  ip address 11.0.0.2 255.255.255.0

 no ip address

 no ip directed-broadcast

 shutdown

!

interface Ethernet4/0/4

 ip address 33.0.0.1 255.0.0.0

 no ip directed-broadcast

 mpls label protocol ldp

 tag-switching ip

!

interface Ethernet4/0/6

 ip address 30.0.0.1 255.0.0.0

 no ip directed-broadcast

 mpls label protocol ldp

 tag-switching ip

!

interface Ethernet4/0/7

 ip address 31.0.0.1 255.0.0.0

 no ip directed-broadcast

 mpls label protocol ldp

 tag-switching ip

!

router ospf 100

 log-adjacency-changes

 redistribute connected

 network 10.0.0.1 0.0.0.0 area 100

 network 30.0.0.0 0.255.255.255 area 100

 network 31.0.0.0 0.255.255.255 area 100

 network 32.0.0.0 0.255.255.255 area 100

 network 33.0.0.0 0.255.255.255 area 100

!

ip classless

R2

redundancy

 no keepalive-enable

 mode hsa

!

ip subnet-zero

ip cef distributed

mpls label protocol ldp

mpls ldp session protection

no mpls traffic-eng auto-bw timers frequency 0

tag-switching tdp router-id Loopback0 force

!

interface Loopback0

 ip address 10.0.0.3 255.255.255.255

 no ip directed-broadcast

!

interface Ethernet5/0/0

 no ip address

 no ip directed-broadcast

 shutdown

 full-duplex

!

interface Ethernet5/0/2

 ip address 32.0.0.1 255.0.0.0

 no ip directed-broadcast

 full-duplex

 mpls label protocol ldp

 tag-switching ip

!

interface Ethernet5/0/6

 ip address 30.0.0.2 255.0.0.0

 no ip directed-broadcast

 ip load-sharing per-packet

 full-duplex

 mpls label protocol ldp

 tag-switching ip

!

interface FastEthernet5/1/0

 ip address 3.3.123.112 255.255.0.0

 no ip directed-broadcast

!

router ospf 100

 log-adjacency-changes

 redistribute connected

 network 10.0.0.3 0.0.0.0 area 100

 network 30.0.0.0 0.255.255.255 area 100

 network 32.0.0.0 0.255.255.255 area 100

!

ip classless

R3

ip cef

no ip domain-lookup

mpls label range 200 100000 static 16 199

mpls label protocol ldp

no mpls traffic-eng auto-bw timers frequency 0

tag-switching tdp router-id Loopback0 force

!

interface Loopback0

 ip address 10.0.0.5 255.255.255.255

 no ip directed-broadcast

!

interface Ethernet1/0

 no ip address

 no ip directed-broadcast

 shutdown

 half-duplex

!

interface Ethernet1/2

 ip address 32.0.0.2 255.0.0.0

 no ip directed-broadcast

 full-duplex

 mpls label protocol ldp

 tag-switching ip

!

interface Ethernet1/4

 ip address 31.0.0.2 255.0.0.0

 no ip directed-broadcast

 full-duplex

 mpls label protocol ldp

 tag-switching ip

!

router ospf 100

 log-adjacency-changes

 redistribute connected

 network 10.0.0.5 0.0.0.0 area 100

 network 31.0.0.0 0.255.255.255 area 100

 network 32.0.0.0 0.255.255.255 area 100

!

ip classless

Additional References

The following sections provide references related to MPLS LDP Session Protection.

Related Documents

Related Topic	Document Title
MPLS LDP	MPLS Label Distribution Protocol
MPLS LDP-IGP Synchronization	MPLS LDP-IGP Synchronization
LDP Autoconfiguration	LDP Autoconfiguration

Standards

Standard	Title
None	—

MIBs

MIB	MIBs Link
•MPLS LDP MIB	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

RFCs

RFC	Title
RFC 3036	LDP Specification
RFC 3037	LDP Applicability

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

Command Reference

This section documents new and modified commands.

New commands

•debug mpls ldp session protection

•mpls ldp session protection

Modified commands

•show mpls ldp neighbor

All other commands used with this features are documented in the Cisco IOS Release 12.3 Command Reference.

debug mpls ldp session protection

To enable the display of events related to Multiprotocol Label Switching (MPLS) Label Distribution Protocol (LDP) Session Protection, use the debug mpls ldp session protection command in privileged EXEC mode. To disable this feature, use the no form of this command.

debug mpls ldp session protection [peer-acl acl]

no debug mpls ldp session protection [peer-acl acl]

Syntax Description

peer-acl acl

(Optional) Enables the display of events for the peers whose router IDs are listed in the access control list.

Defaults

None

Command Modes

Privileged EXEC

Command History

Release	Modification
12.0(30)S	This command was introduced.
12.3(14)T	This command was integrated into Cisco IOS Release 12.3(14)T.
12.2(27)SBA	This command was integrated into Cisco IOS Release 12.2(27)SBA.

Examples

In the following example, the display of events related to MPLS LDP Session Protection are enabled:

Router# debug mpls ldp session protection 

Related Commands

Command	Description
clear mpls ldp neighbor	Forcibly resets an LDP session.
show mpls ldp neighbor	Displays the contents of the LDP.

mpls ldp session protection

To enable MPLS LDP Session Protection for existing Label Distribution Protocol (LDP) sessions or when new sessions are established, use the mpls ldp session protection command in global configuration mode. To disable this feature, use the no form of this command.

mpls ldp session protection [vrf vpn-name] [for acl] [duration seconds]

no mpls ldp session protection [vrf vpn-name] [for acl] [duration seconds]

Syntax Description

vrf vpn-name	(Optional) Specifies VPN routing and forwarding instance (vpn-name) for accepting labels. This keyword is available when the router has at least one VRF configured.
for acl	(Optional) Specifies a standard IP access control list that contains the prefixes that are to be protected.
duration seconds	(Optional) Specifies the number of seconds the LDP Targeted Hello Adjacency should be retained after a link is lost. The default is infinite. The valid range of values is 30 to 2,147,483 seconds.

Defaults

LDP sessions are not established.

Command Modes

Global configuration

Command History

Release	Modification
12.0(30)S	This command was introduced.
12.3(14)T	This command was integrated into Cisco IOS Release 12.3(14)T.
12.2(27)SBA	This command was integrated into Cisco IOS Release 12.2(27)SBA.

Usage Guidelines

This command is not supported under the following circumstances:

•With TDP sessions

•With extended access lists

•With LC-ATM routers

Examples

In the following example, MPLS LDP Session Protection is enabled for LDP sessions for peers whose router IDs are listed in access control list rtr4:

Router(config)# mpls ldp session protection for rtr4

Related Commands

Command	Description
clear mpls ldp neighbor	Forcibly resets an LDP session.
show mpls ldp neighbor	Displays the contents of the LDP.

show mpls ldp neighbor

To display the status of Label Distribution Protocol (LDP) sessions, use the show mpls ldp neighbor command in privileged EXEC mode.

show mpls ldp neighbor [vrf vpn-name] [address | interface] [detail] [graceful-restart]

show mpls ldp neighbor [all]

Syntax Description

vrf vpn-name	(Optional) Displays the LDP neighbors for the specified virtual private network (VPN) routing/forwarding (VRF) instance (vpn-name).
address	(Optional) Identifies the neighbor with this IP address.
interface	(Optional) Defines the LDP neighbors accessible over this interface.
detail	(Optional) Displays information in the long form, including the name or number of the access control list (ACL) used for inbound filtering.
graceful-restart	(Optional) Displays per-neighbor graceful restart information.
all	(Optional) When the all keyword is specified alone in this command, the command displays LDP neighbor information for all VPNs, including those in the default routing domain.

Defaults

If you do not specify a VRF, this command displays information about LDP neighbors for the default routing domain.

Command Modes

Privileged EXEC

Command History

Release	Modification
11.1CT	This command was introduced.
12.0(10)ST	This command was modified to reflect MPLS IETF command syntax and terminology.
12.0(14)ST	This command was modified to reflect MPLS VPN support for LDP.
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.
12.0(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.
12.2(14)S	This command was integrated into Cisco IOS Release 12.2(14)S.
12.0(26)S	This command was integrated into Cisco IOS Release 12.0(26)S. The detail keyword displays information about inbound filtering.
12.0(29)S	The graceful-restart keyword was added.
12.3(14)T	This command was integrated into Cisco IOS Release 12.3(14)T.
12.2(18)SXE	This command was integrated into Cisco IOS Release 12.2(18)SXE.
12.2(27)SBA	This command was integrated into Cisco IOS Release 12.2(27)SBA.

Usage Guidelines

The show mpls ldp neighbor command can provide information about all LDP neighbors, or the information can be limited to the following:

•Neighbor with a specific IP address

•LDP neighbors known to be accessible over a specific interface

This command displays information about LDP and Tag Distribution Protocol (TDP) neighbor sessions.

If you specify the optional detail keyword, the command displays of all the information about the neighbor, including the name or number of the ACL (if any) configured for inbound filtering.

Examples

For explanations of the significant fields shown in the displays, see Table 1.

The following shows sample output from the show mpls ldp neighbor command:

Router# show mpls ldp neighbor

Peer LDP Ident: 203.0.7.7:2; Local LDP Ident 8.1.1.1:1

        TCP connection: 203.0.7.7.11032 - 8.1.1.1.646

        State: Oper; Msgs sent/rcvd: 5855/6371; Downstream on demand

        Up time: 13:15:09

        LDP discovery sources:

          ATM3/0.1

Peer LDP Ident: 7.1.1.1:0; Local LDP Ident 8.1.1.1:0

        TCP connection: 7.1.1.1.646 - 8.1.1.1.11006

        State: Oper; Msgs sent/rcvd: 4/411; Downstream

        Up time: 00:00:52

        LDP discovery sources:

          Ethernet1/0/0

        Addresses bound to peer LDP Ident:

          2.0.0.29        7.1.1.1         59.0.0.199      212.10.1.1

          10.205.0.9 

The following shows sample output from the show mpls ldp neighbor vrf vpn10 command, which displays the LDP neighbor information for the VPN routing/forwarding (VRF) instance named vpn10:

Router# show mpls ldp neighbor vrf vpn10

Peer LDP Ident:14.14.14.14:0; Local LDP Ident 30.29.0.2:0

        TCP connection:14.14.14.14.646 - 30.29.0.2.11384

        State:Oper; Msgs sent/rcvd:1423/800; Downstream

        Up time:02:38:11

        LDP discovery sources:

          ATM3/0/0.10

        Addresses bound to peer LDP Ident:

          3.3.36.9        30.7.0.1        14.14.14.14     30.13.0.1       

          30.15.0.1       30.17.0.1       30.19.0.1       30.21.0.1       

          30.23.0.1       30.25.0.1       30.27.0.1       30.29.0.1       

          30.31.0.1       30.33.0.1       30.35.0.1       30.37.0.1       

          30.39.0.1       30.41.0.1       30.43.0.1       30.45.0.1       

          30.47.0.1       30.49.0.1       30.51.0.1       30.53.0.1       

          30.55.0.1       30.57.0.1       30.59.0.1       30.61.0.1       

          30.63.0.1       30.65.0.1       30.67.0.1       30.69.0.1       

          30.71.0.1       30.73.0.1       30.75.0.1       30.77.0.1       

          30.79.0.1       30.81.0.1       30.83.0.1       30.85.0.1       

          30.87.0.1       30.89.0.1       30.91.0.1       30.93.0.1       

          30.95.0.1       30.97.0.1       30.99.0.1       30.101.0.1      

          30.103.0.1      30.105.0.1      30.107.0.1      30.109.0.1      

          30.4.0.2        30.3.0.2        

The following shows sample output from the show mpls ldp neighbor detail command, which displays information about inbound filtering:

Router# show mpls ldp neighbor vrf vpn1 detail

 Peer LDP Ident: 13.13.13.13:0; Local LDP Ident 33.0.0.2:0

   TCP connection: 13.13.13.13.646 - 33.0.0.2.31581

   State: Oper; Msgs sent/rcvd: 11/10; Downstream; Last TIB rev sent 13

   Up time: 00:02:25; UID: 26; Peer Id 0;

   LDP discovery sources:

    Ethernet1/0/2; Src IP addr: 33.0.0.1 

     holdtime: 15000 ms, hello interval: 5000 ms

   Addresses bound to peer LDP Ident:

    3.3.105.1       13.13.13.13     33.0.0.1        

   Peer holdtime: 180000 ms; KA interval: 60000 ms; Peer state: estab

   LDP inbound filtering accept acl:1

 Peer LDP Ident: 14.14.14.14:0; Local LDP Ident 33.0.0.2:0

   TCP connection: 14.14.14.14.646 - 33.0.0.2.31601

   State: Oper; Msgs sent/rcvd: 10/9; Downstream; Last TIB rev sent 13

   Up time: 00:01:17; UID: 29; Peer Id 3;

   LDP discovery sources:

    Ethernet1/0/3; Src IP addr: 32.0.0.1 

     holdtime: 15000 ms, hello interval: 5000 ms

   Addresses bound to peer LDP Ident:

    3.3.104.1       14.14.14.14     32.0.0.1        

   Peer holdtime: 180000 ms; KA interval: 60000 ms; Peer state: estab

   LDP inbound filtering accept acl:1 

The following shows sample output from the show mpls ldp neighbor all command, which displays the LDP neighbor information for all VPN VRFs, including those in the default routing domain. In this example, the same neighbor LDP ID (14.14.14.14) appears in all of the listed VRF interfaces, which shows that the same IP address can be used in different VPN VRFs.

Router# show mpls ldp neighbor all 

Peer TDP Ident:11.11.11.11:0; Local TDP Ident 12.12.12.12:0

        TCP connection:11.11.11.11.711 - 12.12.12.12.11003

        State:Oper; PIEs sent/rcvd:185/187; Downstream

        Up time:02:40:02

        TDP discovery sources:

          ATM1/1/0.1

        Addresses bound to peer TDP Ident:

          3.3.38.3        30.1.0.2        11.11.11.11     

VRF vpn1:

    Peer LDP Ident:14.14.14.14:0; Local LDP Ident 30.7.0.2:0

        TCP connection:14.14.14.14.646 - 30.7.0.2.11359

        State:Oper; Msgs sent/rcvd:952/801; Downstream

        Up time:02:38:49

        LDP discovery sources:

          ATM3/0/0.1

        Addresses bound to peer LDP Ident:

          3.3.36.9        30.7.0.1        14.14.14.14     30.13.0.1       

          30.15.0.1       30.17.0.1       30.19.0.1       30.21.0.1       

          30.23.0.1       30.25.0.1       30.27.0.1       30.29.0.1       

          30.31.0.1       30.33.0.1       30.35.0.1       30.37.0.1       

          30.39.0.1       30.41.0.1       30.43.0.1       30.45.0.1       

          30.47.0.1       30.49.0.1       30.51.0.1       30.53.0.1       

          30.55.0.1       30.57.0.1       30.59.0.1       30.61.0.1       

          30.63.0.1       30.65.0.1       30.67.0.1       30.69.0.1       

          30.71.0.1       30.73.0.1       30.75.0.1       30.77.0.1       

          30.79.0.1       30.81.0.1       30.83.0.1       30.85.0.1       

          30.87.0.1       30.89.0.1       30.91.0.1       30.93.0.1       

          30.95.0.1       30.97.0.1       30.99.0.1       30.101.0.1      

          30.103.0.1      30.105.0.1      30.107.0.1      30.109.0.1      

          30.4.0.2        30.3.0.2        

VRF vpn2:

    Peer LDP Ident:14.14.14.14:0; Local LDP Ident 30.13.0.2:0

        TCP connection:14.14.14.14.646 - 30.13.0.2.11361

        State:Oper; Msgs sent/rcvd:964/803; Downstream

        Up time:02:38:50

        LDP discovery sources:

          ATM3/0/0.2

        Addresses bound to peer LDP Ident:

          3.3.36.9        30.7.0.1        14.14.14.14     30.13.0.1       

          30.15.0.1       30.17.0.1       30.19.0.1       30.21.0.1       

          30.23.0.1       30.25.0.1       30.27.0.1       30.29.0.1       

          30.31.0.1       30.33.0.1       30.35.0.1       30.37.0.1       

          30.39.0.1       30.41.0.1       30.43.0.1       30.45.0.1       

          30.47.0.1       30.49.0.1       30.51.0.1       30.53.0.1       

          30.55.0.1       30.57.0.1       30.59.0.1       30.61.0.1       

          30.63.0.1       30.65.0.1       30.67.0.1       30.69.0.1       

          30.71.0.1       30.73.0.1       30.75.0.1       30.77.0.1       

          30.79.0.1       30.81.0.1       30.83.0.1       30.85.0.1       

          30.87.0.1       30.89.0.1       30.91.0.1       30.93.0.1       

          30.95.0.1       30.97.0.1       30.99.0.1       30.101.0.1      

          30.103.0.1      30.105.0.1      30.107.0.1      30.109.0.1      

          30.4.0.2        30.3.0.2        

VRF vpn3:

    Peer LDP Ident:14.14.14.14:0; Local LDP Ident 30.15.0.2:0

        TCP connection:14.14.14.14.646 - 30.15.0.2.11364

        State:Oper; Msgs sent/rcvd:1069/800; Downstream

        Up time:02:38:52

        LDP discovery sources:

          ATM3/0/0.3

        Addresses bound to peer LDP Ident:

          3.3.36.9        30.7.0.1        14.14.14.14     30.13.0.1       

          30.15.0.1       30.17.0.1       30.19.0.1       30.21.0.1       

          30.23.0.1       30.25.0.1       30.27.0.1       30.29.0.1       

          30.31.0.1       30.33.0.1       30.35.0.1       30.37.0.1       

          30.39.0.1       30.41.0.1       30.43.0.1       30.45.0.1       

          30.47.0.1       30.49.0.1       30.51.0.1       30.53.0.1       

          30.55.0.1       30.57.0.1       30.59.0.1       30.61.0.1       

          30.63.0.1       30.65.0.1       30.67.0.1       30.69.0.1       

          30.71.0.1       30.73.0.1       30.75.0.1       30.77.0.1       

          30.79.0.1       30.81.0.1       30.83.0.1       30.85.0.1       

          30.87.0.1       30.89.0.1       30.91.0.1       30.93.0.1       

          30.95.0.1       30.97.0.1       30.99.0.1       30.101.0.1      

          30.103.0.1      30.105.0.1      30.107.0.1      30.109.0.1      

          30.4.0.2        30.3.0.2        

VRF vpn4:

    Peer LDP Ident:14.14.14.14:0; Local LDP Ident 30.17.0.2:0

        TCP connection:14.14.14.14.646 - 30.17.0.2.11366

        State:Oper; Msgs sent/rcvd:1199/802; Downstream

The following example shows the Graceful Restart status of the LDP neighbors:

Router# show mpls ldp neighbor graceful-restart

Peer LDP Ident: 20.20.20.20:0; Local LDP Ident 17.17.17.17:0

    TCP connection: 20.20.20.20.16510 - 17.17.17.17.646

    State: Oper; Msgs sent/rcvd: 8/18; Downstream

    Up time: 00:04:39

    Graceful Restart enabled; Peer reconnect time (msecs): 120000

Peer LDP Ident: 19.19.19.19:0; Local LDP Ident 17.17.17.17:0

    TCP connection: 19.19.19.19.11007 - 17.17.17.17.646

    State: Oper; Msgs sent/rcvd: 8/38; Downstream

    Up time: 00:04:30

    Graceful Restart enabled; Peer reconnect time (msecs): 120000

Table 1 describes the significant fields in the sample displays shown above.

Table 1 show mpls ldp neighbor Field Descriptions 

Field	Description
Peer LDP Ident	LDP identifier of the neighbor (peer) for this session.
Local LDP Ident	LDP identifier for the local label switch router (LSR) for this session.
TCP connection	TCP connection used to support the LDP session, shown in the following format: •peer IP address.peer port •local IP address.local port
State	State of the LDP session. Generally this is Oper (operational), but transient is another possible state.
Msgs sent/rcvd	Number of LDP messages sent to and received from the session peer. The count includes the transmission and receipt of periodic keepalive messages, which are required for maintaining the LDP session.
Downstream or Downstream on Demand	Indicates the downstream method of label distribution that is being used for this LDP session. When the downstream method is used, an LSR advertises its locally assigned (incoming) labels to its LDP peer (subject to any configured access list restrictions). When the Downstream on Demand method is used, an LSR advertises its locally assigned (incoming) labels to its LDP peer only when the peer asks for them.
Up time	Length of time the LDP session has existed.
UID	Used for troubleshooting.
Peer Id	Used for troubleshooting.
LDP discovery sources	Source(s) of LDP discovery activity that led to the establishment of this LDP session.
Addresses bound to peer LDP Ident	The known interface addresses of the LDP session peer. These are addresses that might appear as next hop addresses in the local routing table. They are used to maintain the Label Forwarding Information Base (LFIB).
Peer holdtime	The time the neighbor session will be retained without the receipt of an LDP message from the neighbor.
KA interval	Keep Alive Interval. The amount of time a router lets pass without sending an LDP message to its neighbor. If this time elapses and the router has nothing to send, it will send a Keep Alive message.
LDP inbound filtering accept acl	Access list that is permitted for inbound label binding filtering.
Graceful Restart	Indicates whether the LDP session has LDP Graceful Restart enabled.
Peer Reconnect Time	The length of time the peer router waits for a router to reconnect.

Related Commands

Command	Description
show mpls ldp discovery	Displays the status of the LDP discovery process.

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