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

[Richard Mikisa]

Hi all

Issue was mismatched MTU. I reduced them down to 2000 after a ping
sweep and its been steady since.

On Thu, Jul 18, 2019 at 3:18 AM Mike
<mike-cisconsplist at tiedyenetworks.com> wrote:
>
> 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.
>
>
> Mike-
>
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-- 
cheers
Richard