Common Causes:
- The route between LSP peers is flapping.
- The LDP session flaps.
Procedure:
1. Check that the routes alternate between unreachable and reachable.
Run the display ip routing-table command to check information about the routes to the destination of the LSP. Run this command at 1-second interval. If routes exist, routing information is displayed. If no routes exist, no routing information is displayed. If sometimes routing information is displayed but sometimes not after the command is run several times, the routes alternate between unreachable and reachable.
- If routes alternate between unreachable and reachable or no route is displayed, see The Ping Operation Fails and rectify the fault in IGP routes.
- If the routes are always reachable, go to Step 2.
2. Check that the LDP session flaps.
Run the display mpls ldp session command to check the Status field. Running this command every second is recommended. If Operational and Initialized are displayed alternatively, the LDP session flaps.
- If the LDP session flaps, see LDP Session Flapping.
- If the LDP session does not flap, go to Step 3.
3. Collect the following information, and contact technical support personnel.
Results of the preceding troubleshooting procedure
Configuration files, logs, and alarms
https://support.huawei.com/enterprise/en/doc/EDOC1000079719/22ae4e31/ldp-lsp-flapping
