Inheritance of Corrupt Routing Table?

[Daran Blackwell]

Hello all,

This is a theoretical newbie query/question I have been wondering about (+ bit concerned about tbh..).

We had a situation at our company before where after one of our two on-site WAN routers had an IOS upgrade a bug caused by the IOS versions being out of parity corrupted one of the devices routing tables, and this manifested in causing problems getting LAN traffic out to WAN and vice versa.

At the time the senior network guy in our company sorted it, and he told me that he could see that one router has a lot less routes in it that should have been and he issued a clear ip ospf command to clear out the LAN routes. This has left me wondering (in case he's away and it happens again!) if say you repeated that command and/or tried to resolve the issue by a reboot of the corrupted router, could it's bad table be inherited / passed on to the other good router thereby corrupting that devices table also?

I have not gotten onto routing in my studies yet being a LAN man at the moment, but I do understand that the OSPF LAN routes from our distribution switches should be learned by the WAN routers, but is it possible that missing static routes on a corrupt table be 'learned' by another router therefore wiping out both tables and leaving a big hole in your tables even if they are no longer technically corrupted?

Any explanation appreciated.

Cheers,

[paolo bevilacqua]

One would have to look at the details of the problem, however the short answer is that if one router is propagating wrong routing information, clearing it or reloading it will remove the wrong information sent to other routers.

This the general theory, then it is surelly possible to come up with particular scenarios where that doesn't happen.

[Daran Blackwell]

Thanks Paolo. But as a follow up if a corrupt table has been passed on to another router isn't that router then corrupted also, and therefore needing to be cleared or does it always follow that the route inheritance is remembered so that if the original corrupt router table is cleared then that is then passed on router #2?

Cheers,