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routes completely dropped from the node while running L2TP LNS service
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We're running L2TP LNS with MPLS-PE functionality terminating subscribers to 186 VRFs. During the tests i see constant issue with the node when it drops all routes learnt from frr daemons. All the BGP peers go down and the node can be recovered only with reboot.
I tried to use some debug logging for FRR, but can't see any particular messages pointing to the root cause.
The latest test logs contain:

  1. FRR logs with zebra kernel, bgp neighbor-events and nht debugging
  2. System syslog covering the issue. The problem starts at 23:40:51 with Network unreachable messages from accel-ppp daemon
  3. Some show commands after the problem occured
  4. system configuration

The size of the logging is too big for the upload, so sharing it here:

There is no visible reason for the routes to be dropped. The amount of subscribers at the time of the issue varies from 3k to 10k+
If you can advice what logs&debugs should be turned on additionally - we can repeat the tests next maintenance window.


Difficulty level
Unknown (require assessment)
Why the issue appeared?
Will be filled on close
Is it a breaking change?
Unspecified (possibly destroys the router)
Issue type
Bug (incorrect behavior)

Event Timeline

Actually only multihop BGP peers go down. Others are up, but the routes received from them does not go to kernel, so the connectivity drops.
Latest techsupport:
The system was alive more than 12 hours, but crashed the same way as before.