So, I can't remember what prompted me to test this but I came across an interesting issue.
we are pretty much taught that when you setup an OSPF instance you should set the router ID to an ip that exist on a loopback interface (in Mtik, that means using a bridge).
We are taught to do this because the interface never goes down (unless the router explodes or is turned off, mute point) and so the instance that is associating itself with the interface ip will not go down.
In my younger years saw first hand what happens when you don't use this.
So, using GNS3 and the new CHR router image I setup three routers with router IDs as 18.104.22.168 22.214.171.124 126.96.36.199
I setup bridges for those IPs as well. then constructed the interlink IPs and ospf network.
Next I turned off the bridge on one of the routers. I expected the OSPF to go down but it did not.
I tried a few things and in the end I have removed the bridges and their IPs and yet the OSPF still stays active.
I even rebooted to make sure.
So, this is the question, why is it staying up. what have I missed.
*Edit: I've just done the exact same thing on some Huaweis and I get the exact same result.
Gonna try some ciscos
*Edit: Cisco is the same