I am running an OSPF network. Each one of my routers has two subnets. 10.1.x.0/24 and 10.21.x.0/24 for the first time yesterday, I found that the neighboring routers received both subnets and showed them in their LSA tables, but only the first, or 10.1.x.0/24 subnet was installed as a route. This left 10.21.x.0/24 not being installed. Therefore traffic had no return path for data on 10.21.x.0/24 subnet.
Starting and stopping OSPF on the neighboring interface caused the tables to be repopulated, and the routes were then installed properly. This is very perplexing though, because we have been running this configuration for about three years and have never seen this problem, and it did not happen to all routers, only a handful.
And on the routers where it happened, some of them were connected and some were not.
Any ideas here?
Thanks,
Dan Darden.