OSPF, Areas and Weirdness...

rakem

trying to get back into the wonderful world that is OSPF but having some issues at the moment,
I configured a network like the image below, all routers in a single area (0) all with the same bandwidth on every link. Some routers are connected via serial xover, others by ethernet xover.



So obviously there are multiple paths around the three routers all connected together, however when i shutdown an interface on a router, OSPF would not re-calculate a new route and my pings would keep dropping out since a new route was not put into the routing table.



Now then i configured the same network but this time with areas as shown in the figure below, did the same thing, shut down an interface, but this time OSPF would recalculate a new route and after a few timeouts my pings would get replies using the newly calculated route..



so why would my setup with a single area fail to re-calculate a new route?

i know im asking a lot without posting configs here but im tired and about to go to bed so i can post configs later if necessary... just wondering if im missing something blindingly obvious here.

dtlokee

When you shut down the link, did you see the neighbors change state to down? Did you see all your neighbors in the output of show ip ospf neighbors? I think you were missing a neighbor adjacency. Regardless of the area configuration, it will fail over to any backup link, although it may take some time to do that based on the dead timer (40-120 seconds with an indirect link failure)

rakem

the interfaces did go to the down state, but when i did the show ip ospf neighbors command the neighbour was gone..

i think you are correct, i was probably missing an adjacency... probably just a config mistake.

Paul Boz

use "debug ip ospf events" to see if the relationships are actually bouncing or not.

rakem

yea it was just a miss config problem, actually had an incorrect wildcard mask so the interface wasnt getting advertised... all good now.