LDP session protection enables a device to start the extended LDP discovery mechanism to continue to maintain an LDP session established with an LDP peer if the basic LDP discovery mechanism fails. After the basic LDP discovery mechanism recovers, the LDP protocol can rapidly converge.
If the direct link of a local LDP session between two devices fails, an LDP adjacency for the LDP session is torn down. The LDP session and related labels are also deleted. After the direct link recovers, the LDP session can be reestablished and distribute labels so that an LDP LSP over the session can converge. During this process, LDP LSP traffic is dropped.
With LDP session protection configured, LDP establishes a remote adjacency when establishing local adjacencies and uses both adjacencies to maintain LDP sessions. If the direct link of an LDP session is faulty and other paths and routes are available, the remote adjacency can be used to maintain the LDP session without interruption. After the direct link recovers, the local outgoing label can still be used, without being distributed by the downstream node again. The LDP session does not need to be reestablished. This speeds up LDP LSP convergence and reduces traffic loss.
The system view is displayed.
The MPLS-LDP view is displayed.
LDP session protection is configured.
The parameter description is as follows.
| Parameter | Description | Value |
|---|---|---|
| peer-group peer-group-name | Name of an LDP peer group. The parameter is specified using the ip ip-prefix command. | The name is a string of 1 to 169 case-sensitive characters, spaces and question marks are not supported. When double quotation marks are used around the string, spaces are allowed in the string. |
| duration | Period of time, during which LDP session protection remains effective. | - |
| infinite | LDP session protection remains effective permanently. | - |
| time-value | Period of time, during which LDP session protection remains effective. | The value is an integer ranging from 30 to 2147483, in seconds. |
The configuration is committed.
After completing the configurations, run the display mpls ldp remote-peer command in any view to view the LDP session protection configuration and the function status. The command output shows that this function takes effect.