OSPF Fluctuations every 32 Minutes in CSC Environment

Unanswered Question
May 18th, 2009

Hello Experts,

We experience the OSPF Fluctiations every 32 Minutes i.e. configured between PE & 'CSC' Router.

Note: It's a CSC Setup.

Few points are:


1) Last Mile is Healthy

2) OSPF Configuration are Fine

3) No MTU Related issues.

Can someone help in identifying the exact cause for the same.

Best Regards,

Guru Prasad R

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Giuseppe Larosa Mon, 05/18/2009 - 04:18

Hello Guru,

each OSPF LSA is refreshed by the original owner every 30 minutes on average, (LSA group pacing waits to collect a group of LSAs to refresh).

A new version of LSAs trigger a SPF recalculation and this might explain what you see.

Hope to help


guruprasadr Mon, 05/18/2009 - 05:22

Hello Giuseppe,

Thanks for the Reply.

I tried 'LSA Group Pacing' in CSC Router, but the problem was continue to be existing.

Any more help, would be really Appreciable.

Best Regards,

Guru Prasad R

Giuseppe Larosa Mon, 05/18/2009 - 05:36

Hello Guru,

I would suggest you to better define the problem:

what do you mean with OSPF fluctuations?

I may guess you can experience temporary loss of MPLS connectivity but it is a wild guess.

In this case you can try to play with LDP synchronization



on in the field of MPLS LDP graceful restart


Hope to help



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