ospf ldp-sync

Function

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

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

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

Format

ospf ldp-sync

undo ospf ldp-sync

Parameters

None

Views

Ethernet interface view, Ethernet sub-interface view, Eth-Trunk interface view, Eth-Trunk sub-interface view, Tunnel interface view, Dialer interface view, VLANIF interface view, Virtual-Template interface view, BDIF interface view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

LDP converges slower than OSPF routes, causing traffic loss on a network configured with active and standby links.

If an active link fails, an OSPF route of a standby link becomes reachable and a backup label switched path (LSP) over the standby link takes over traffic. This process is implemented usually using LDP FRR. After the active link recovers, the OSPF route of the active link becomes reachable before an LDP session is established over the active link. As a result, traffic is dropped over the reachable OSPF route along the unreachable LSP.
When the OSPF route of the active link is reachable and an LDP session between two nodes on the active link fails, traffic is directed using the IGP route of the active link, whereas the LSP over the active link is torn down. As the preferred IGP route of the standby link is unavailable, an LSP over the standby link cannot be established, causing LSP traffic loss.

The ospf ldp-sync command can be used on the interface at intersection of the active and standby link to enable LDP and OSPF synchronization to prevent traffic loss.

Example

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

<sysname> system-view
[sysname] interface GigabitEthernet 0/0/1
[sysname-GigabitEthernet0/0/1] ospf ldp-sync