ospf ldp-sync

Function

The ospf ldp-sync command enables synchronization between LDP and OSPF on an interface.

The undo ospf ldp-sync command disables synchronization between LDP and OSPF on an interface.

By default, synchronization between LDP and OSPF is disabled on an interface.

Format

ospf ldp-sync

undo ospf ldp-sync

Parameters

None

Views

Interface view

Default Level

2: Configuration level

Usage Guidelines

The LDP convergence speed depends on the convergence speed of OSPF routes. To enable MPLS LDP on a network with the primary and backup links, the following problems may occur:

Upon a fault on the active link, OSPF routes and ISP are switched to the backup link using LDP FRR. When the primary link recovers, OSPF routes are switched back to the primary link earlier than LDP traffic because IGP route convergence is faster than LDP convergence. As a result, LSP traffic is lost.
If a fault occurs on the LDP session between nodes on the primary link where the OSPF routes are working properly, the OSPF routes still use the primary link and the LSP on the primary link is deleted. No OSPF route exists on the backup link; therefore, no LSP can be established on the backup link. LSP traffic is lost.

Run the ospf ldp-sync command to enable synchronization between LDP and OSPF to prevent traffic loss in the preceding problems. Run this command on the interfaces on both ends of the link between the node where the primary LSP and the backup LSP diverge from each other and its LDP peer on the primary LSP.

Example

# Enable synchronization between LDP and OSPF on VLANIF100.

<HUAWEI> system-view
[HUAWEI] interface vlanif 100
[HUAWEI-Vlanif100] ospf ldp-sync

# Enable synchronization between LDP and OSPF on GE0/0/1.

<HUAWEI> system-view
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] undo portswitch
[HUAWEI-GigabitEthernet0/0/1] ospf ldp-sync