Saturday, September 18, 2021

Problem implementing OSPF

Our current network uses all static routes. I've been wanting to implement OSPF but it's one of those things that always gets kicked to the side since other stuff is "more urgent." I was reading that the simplest way to start would be to just leave all my statics setup, implement OSPF, put everything in area 0, verify that the OSPF routes looked correct, and then slowly start to remove the static routes. since the statics would have a lower cost by default, the idea sounded great because there really shouldn't be any risk of messing anything up (haha).

So, I started with just 2 routers that connect Site 1 and Site 2 together, but instantly ran into an issue. I had a static route set for a /23 subnet, but OSPF learned/generated a /24 include within that /23 and sent it somewhere else, which brough that segment down.

Being new to OSPF, I'm not sure how to find out where OSPF is learning/generating routes from or how to resolve the issue, so I disabled it for now. Basically looking for some info on how to find out where routes are being learned, why, and what to do in a situation like this. I'm just not familair enough with how it works and what to look for. Maybe if I had enabled it on all the vlans on the switches, that may have solved the issue, but I couldn't leave that network down for too long, especially since I knew the easy fix.

Here's a simple toplogy with some snippets of the code on those devices. Hopefully there's enough info here but if any additional info would help I can gladly send it

https://imgur.com/a/3b6B40u



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