After getting familiar with the FA, when it’s set and when not, we’re ready to cook the recipe for chaos: NSSAs, Default Route injection and Forwarding Address.
The theme question is actually quite a good one, because it may seem like the fight has already been won by IS-IS in the Service Provider segment, and by OSPF on the enterprise market. So why ask it then? Well, because I got the following answer one too many times: “IS-IS is awesome, OSPF not so much. I have no idea how IS-IS works but it’s great. OSPF is so complicated and offers so little flexibility…”.
Hoping you all enjoyed the first part of the OSPF forwarding address saga, I’m back with the promise to make things clear regarding a nicely built redistribution case. I’m not sure if you’ve ever come across it, or ever will, but it’s interesting because it explains why we need the rules to set the forward address (if you don’t remember them, you can take a look at Part I).
OSPF (Open Shortest Path First) is mostly seen as a pretty nasty routing protocol, with a load of subtleties and corner cases. I’ve decided to talk about a subject which usually gives a lot of troubles to most network professionals – the Forwarding Address (FA).