[c-nsp] Strange RIP behaviour

[Michael Costello]

> router rip
>  version 2
>  timers basic 3 10 0 10
>  redistribute connected
>  redistribute static
>  passive-interface default
>  no passive-interface FastEthernet0/32
>  network 1.0.0.0
>  neighbor 1.2.2.3
>  neighbor 1.2.2.4
>  no auto-summary
> 
> During the outage (that affected only this customer out of 40 on this 3550),
> it showed:
> 
> 1.6.7.8/28    possibly down
> 1.2.3.4/30 directly connected, FastEthernet0/35
> 
> What strikes me is: how could it be possible to have a static selected as
> possibly down, when the connected route is (and has always be) up? I could
> ping the point to point fine from the router, no problems. The way to
> recover was simply to shut/unshut the relevant interface. Any hints what
> could be happened?


The route should stay "possibly down" until the holddown timer
expires, which appears to be never.  You could try to configure a
non-zero value for the holddown timer and watch where the route ends
up pointing.  Otherwise debup ip rip and see what the router is
interpreting as the cause of marking the route possibly down.  If you
decide to modify timer values, make sure to do it on every router in
your routing domain.