[c-nsp] OSPF flapping between Nexus 7000 and ASR 1001x

Mike mike-cisconsplist at tiedyenetworks.com
Wed Jul 17 22:17:45 EDT 2019

On 7/17/19 6:54 AM, Łukasz Bromirski wrote:
>> On 9 Jul 2019, at 17:58, Richard Mikisa <rmikisa at gmail.com> wrote:
>> Hi All,
>> I am running OSPF across a point to point link between a Nexus 7000
>> and an ASR1000x.
>> The OSPF works fine but every couple of hours, it breaks and neighbor
>> state goes into EXCHANGE and remains there for another 40 minutes or
>> so. It then goes into full, OSPF comes up and all is well for another
>> couple of hours or so and then the cycle starts again. All the time,
>> IP connectivity between the two point to point IPs is up.
> Apart from OSPF config changes already mentioned, check what’s going
> on in your CoPP policies on both ends. This doesn’t look like a directly
> config-related problem, rather environmental (like circuit switchover and
> problems with MTU) but it may also be something related to amount
> of traffic hitting CoPP policies from time to time and OSPF traffic overflowing
> defined queues.

You can do some debugging on ip ospf adjacency and such. I have seen
cases like this where there have been duplicate loopback ip's, duplicate
ptp link id's, and such, which cause similar results. The adjacency
debugging should give you more of a reason WHY the adjacency is going down.

Post your results if you find the cause.


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