Configuring Synchronization Between Ldp And Igp; Establishing The Configuration Task - Huawei Quidway S9300 series Configuration Manual

Quidway S9300 Terabit Routing Switch
Configuration Guide - MPLS
Procedure
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Example
Enable LDP Auto FRR. You can view that the backup LSP to the destination 2.2.2.9/32 has
already been set up. The configuration result is as follows:
[Quidway] display mpls lsp
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
FEC
2.2.2.9/32
**LDP FRR**
2.2.2.9/32
3.3.3.9/32
3.3.3.9/32
4.4.4.9/32
4.4.4.9/32
10.1.3.0/24
10.1.4.0/24

2.9 Configuring Synchronization Between LDP and IGP

By configuring LDP and IGP synchronization, you can delay the route switchback by
suppressing the setup of IGP neighbor relationship till an LDP session is established.

2.9.1 Establishing the Configuration Task

Before configuring LDP and IGP synchronization, familiarize yourself with the applicable
environment, complete the pre-configuration tasks, and obtain the required data. This can help
you complete the configuration task quickly and accurately.
Applicable Environment
In the networking where primary and backup LSPs are used, synchronization between LDP and
IGP is applied to avoid traffic loss in case the primary LSP fails. The situations are as follows:
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Issue 04 (2011-12-26)
Run the display mpls lsp command to view information about the established backup LSP
after LDP Auto FRR is enabled.
LSP Information: LDP LSP
In/Out Label
NULL/3
/1025
1024/3
**LDP FRR** /1025
NULL/3
**LDP FRR** /1025
1025/3
**LDP FRR** /1025
NULL/1026
**LDP FRR** /1026
1026/1026
**LDP FRR** /1026
1027/3
1028/3
**LDP FRR** /1027
When the primary LSP fails, the IGP traffic and LSP traffic are switched to the backup
LSP. When the primary LSP recovers, IGP converges faster than the creation of the LDP
session. Thus, IGP traffic is switched back to the primary LSP before the LDP session is
set up. This causes the loss of LSP traffic.
When the primary LSP runs normally whereas the LDP sessions between the nodes along
the primary LSP fail, the LSP is deleted, and the LSP traffic is lost. The IGP traffic, however,
is still transmitted along the primary link.
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In/Out IF
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2 MPLS LDP Configuration
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