[c-nsp] OSPF issue

[Pete Templin]

On 11/11/11 6:30 PM, John Elliot wrote:
>
> OSPF Issue Hope someone can assist with an ospf problem - We have an
> existing ospf adj running fine between R1+R2, we have just
> provisioned a second link, enabled ospf and we see it form adjacency
> which lasts ~60seconds, then R1 sees R2 as dead, and R2 Cannot see
> ourself in hello from R1, and then the whole thing starts again.
>
> With both adj. up(From R1): Neighbor ID     Pri   State
> Dead Time   Address         Interfacexxx.xxx.76.248    1   FULL/DR
> 00:00:00    xxx.xxx.66.62   Port-channel1.87xxx.xxx.76.248    1
> FULL/DR         00:00:39    xxx.xxx.66.2    FastEthernet3/0
>
> Then "new" link loses adj. after ~60seconds Neighbor ID     Pri
> State           Dead Time   Address         Interfacexxx.xxx.76.248
> 1   FULL/DR         00:00:38    xxx.xxx.66.2    FastEthernet3/0
>
> NB - pings to/from both R1+R2 are clean(No loss/excessive latency),
> and both ends(Ints) set to mtu of 1500.

Right, both ends are set to mtu of 1500.  Does it pass 1500?

ping <far-side> df size 1500

I'm suspecting an intermediate (carrier) MTU problem.  Neighboring up
uses small-enough packets, but delivering the initial load of routing
data hits the MTU problem and the session melts down.

pt