When you configure OSPF network statements, IOS orders them most-specific to least-specific then does a top-to-bottom match of the interfaces. It doesn’t matter which order you put them in, the configuration will always be ordered with the longest prefix matches first. Lab time!
Tag: ospf
For both OSPF and EIGRP routers to become neighbors, their interface’s primary IP address must be on the same subnet. That statement is true. There is a subtle difference between the two, though.
This isn’t hard stuff at all. I’m sure there are a couple of cool tricks I don’t know yet, but let’s try anyway.
Here’s a story from last week with little of no teaching value. I got a call from one of our business units looking for some routing help. We don’t usually care about their production networks, but they were seeing some funky traceroutes, so I agreed to try and help them out.
I was studying via Google+ Hangout the other day with CJ and Rob, and one of the topics that came up was the idea of OSPFv2 advertising all loopbacks as 32-bit no matter what the configured mask is. I rarely use loopbacks outside of a lab and had no idea, so I set up a quick lab to see for myself. Sure enough! That’s exactly what I saw.
Corrections appreciated.
Corrections are always welcome.