Regular OSPF-5-ADJCHG On Core Routers

[kvitug]

Hello, 

 We have recently mentioned that on our core production routers we are getting constant, almost exactly every 10 min the following OSPF-5-ADJCHG: 

0337: .Apr 28 20:26:54.812: OSPF-5-ADJCHG: Process 7000, Nbr 188.143.143.12 on Vlan25 from LOADING to FULL, Loading Done

And about 10 min later: 

0338: .Apr 28 20:35:34.599: %OSPF-5-ADJCHG: Process 7000, Nbr 188.143.143.12 on Vlan25 from FULL to DOWN, Neighbor Down: Dead timer expired

We have mentioned that couple of months ago the CPU on the core routers spiked from 10% to about 20% and this is when we started seeing those ADJ changes but no changes were made on either device or in the network at all. 

The CPU process is showing that most resources are taken by "IP Input" and "BGP Router" 

CPU utilization for five seconds: 15%/7%; one minute: 16%; five minutes: 16%

The CPU spike is the only inconsistency that we see correlates with the time when we started seeing %OSPF-5-ADJCHG. 

Could you please advise if there is direction that we should look at to alleviate this issues? 

Thank you! 

[Leo Laohoo]

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@kvitug wrote:

0338: .Apr 28 20:35:34.599: %OSPF-5-ADJCHG: Process 7000, Nbr 188.143.143.12 on Vlan25 from FULL to DOWN, Neighbor Down: Dead timer expired

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Check this side of the network and confirm the WAN link isn't flapping. 
NOTE:  Some people like to disable link logging (i.  e.  when a link goes down/up the event won't show up in the logs).  If it is disabled, enable it.  

[kvitug]

Thank you for the suggestion Leo!
Unfortunately, the logging is enabled and we do see the state of the physical interface if it goes down.

[Vishnu Vardhan S]

Ping the neighbor device cont. and check if the unicast reach-ability fails. 

[paul driver]

Hello

sounds like a possible interface/neighbour flap due possible spf recalculations

router ospf xx

ospf log-adjacency-changes

sh ip ospf | in SPF

sh log | in OSPF

debug ip ospf monitor

[kvitug]

Thank you!

Will try that and will let you know of our findings.