OSPF Adjacency Flapping

[kaustav.gupta]

Hi,

Under what conditions can the OSPF adjacency after going to full state and complete database exchange tears down and again sets up again.

Regs

Kas

[Adam Frederick]

If your layer 2 topology is stable, I would look for network type problems (i.e hello/dead timers). Can you post a "show ip ospf interface serial0/0" from both routers. Replace serial0/0 with correct output (i.e. fastethernet0/0, serial0/0/0, etc). Also a "show interface" from each end will help to identify any errors. If your comfortable debugging, debug ip ospf adj should help as well.

[Danilo Dy]

Try this link http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800949f7.shtml

[amit-singh]

Hi Kas,

Following could be the reason for the adjaceny break up.

1. If the router doesnot receive hello packet from the neighbor router with in the specified hello timer.

2. If your link is unstable between the routers.

3. If some miscofiguration happen on one of the router like setting up the router link in a Stub area, misconfigured subnet mask of the interface connecting the two routers, misconfigured hello/dead interval.

For the adjacency to set up again all the criteia in point 3 should be matched.

HTH,

-amit singh

[kaustav.gupta]

Hi,

Now the problem has resolved. No changes made. It could be the link stability bcos out of the 4 hello packets maybe some were missed or cpu utilization which has now dropped from 87% to 13%. No misconfigurations checked.

Anyways thanks to all of you guys..

Regs

Kas