Example for Configuring LDP Session Protection

This session provides an example for configuring LDP session protection. The configuration involves configuring a local LDP session and the LDP session protection function.

Networking Requirements

In Figure 1, an LDP session is established between PE1 and PE2. If the direct link between PE1 and PE2 fails, the LDP session is expected to remain connected. To meet this requirement, if a redundancy link between PE1 and PE2 is available, LDP session protection can be configured for the LDP session between PE1 and PE2. If the direct link between PE1 and PE2 fails, LDP session protection prevents the LDP session from being disconnected and the LDP peer relationship from being torn down.

Figure 1 LDP session protection

Interfaces 1 and 2 represent GE 0/1/0 and GE 0/1/1, respectively.

Configuration Roadmap

The configuration roadmap is as follows:

Assign an IP address to each interface and configure IGP routes.
Configure a local LDP session.
Configure LDP session protection.

Data Preparation

To complete the configuration, you need the following data:

**Table 1** Data to be prepared
Device Name	Data Item	Value
PE1	Period of time session protection remains effective	Infinite
PE2	Period of time session protection remains effective	Infinite

Procedure

Assign an IP address to each interface and configure IGP routes. For configuration details, see Configuration Files in this section.

Configure a local LDP session.

# Configure PE1.

<PE1> system-view
[~PE1] mpls lsr-id 1.1.1.1
[*PE1] mpls
[*PE1-mpls] quit
[*PE1] mpls ldp
[*PE1-mpls-ldp] quit
[*PE1] interface gigabitethernet 0/1/1
[*PE1-GigabitEthernet0/1/1] mpls
[*PE1-GigabitEthernet0/1/1] mpls ldp
[*PE1-GigabitEthernet0/1/1] quit
[*PE1-GigabitEthernet0/1/1] commit

# Repeat this step for PE2. For configuration details, see Configuration Files in this section.

Configure LDP session protection.

# Configure PE1.

[~PE1] mpls ldp
[*PE1-mpls-ldp] session protection duration infinite
[*PE1-mpls-ldp] commit
[~PE1-mpls-ldp] quit

# Configure PE2.

[~PE2] mpls ldp
[*PE2-mpls-ldp] session protection duration infinite
[*PE2-mpls-ldp] commit
[~PE2-mpls-ldp] quit

Verify the configuration.

# Run the shutdown command to disable PE1's GE 0/1/1 to simulate a link fault. Then run the display mpls ldp remote-peer command on PE1. The command output shows that LDP session protection has taken effect.

[~PE1] display mpls ldp remote-peer 
                         LDP Remote Entity Information
 ------------------------------------------------------------------------------
 Remote Peer Name  : pe2
 Description       : ----
 Remote Peer IP    : 3.3.3.3              LDP ID        : 1.1.1.1:0
 Transport Address : 1.1.1.1              Entity Status : Active

 Configured Keepalive Hold Timer : 45 Sec
 Configured Keepalive Send Timer : ----
 Configured Hello Hold Timer     : 45 Sec
 Negotiated Hello Hold Timer     : 45 Sec
 Configured Hello Send Timer     : ----
 Configured Delay Timer          : 10 Sec
 Hello Packet sent/received      : 91/86
 Label Advertisement Mode        : Downstream Unsolicited
 Auto-config                     : Session-Protect
 Session-Protect effect          : YES
 Session-Protect Duration        : infinite
 Session-Protect Remain          : ----
 ------------------------------------------------------------------------------
 TOTAL: 1 Remote-Peer(s) Found.

Configuration Files

PE1 configuration file

#
sysname PE1
#
mpls lsr-id 1.1.1.1
#
mpls
#
mpls ldp
 session protection duration infinite
 #
 ipv4-family
#
isis 1
 is-level level-2
 network-entity 10.0000.0000.0001.00
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.1 255.255.255.252
 isis enable 1
#
interface GigabitEthernet0/1/1
 undo shutdown
 ip address 10.1.2.1 255.255.255.252
 isis enable 1
 mpls
 mpls ldp
#
interface LoopBack0
 ip address 1.1.1.1 255.255.255.255
 isis enable 1
#
return

PE3 configuration file

#
sysname PE3
#
isis 1
 is-level level-2
 network-entity 10.0000.0000.0003.00
#               
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.2 255.255.255.252
 isis enable 1
#
interface GigabitEthernet0/1/1
 undo shutdown
 ip address 10.1.3.1 255.255.255.252
 isis enable 1
#
interface LoopBack0
 ip address 2.2.2.2 255.255.255.255
 isis enable 1
#
return

PE2 configuration file

#
sysname PE2
#
mpls lsr-id 3.3.3.3
#
mpls
#
mpls ldp
 session protection duration infinite
 #
 ipv4-family
#
isis 1
 is-level level-2
 network-entity 10.0000.0000.0002.00
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.3.2 255.255.255.252
 isis enable 1
#
interface GigabitEthernet0/1/1
 undo shutdown
 ip address 10.1.2.2 255.255.255.252
 isis enable 1
 mpls
 mpls ldp
#
interface LoopBack0
 ip address 3.3.3.3 255.255.255.255
 isis enable 1
#
return