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!
Let’s get an IPv4 default route into EIGRP. There are a few methods to do it. I hate most of them, though. I think it will be obvious which one I like. LOL
I wanted to do some analysis of the EIGRP topology table last night, so I fired up a small lab. I was especially interested in how external routes appear there and compare to internal entries. Like all good scientific endeavors, the whole thing got derailed when I made a realization.
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.
Are you sensing a theme lately? Since we covered the basics of the main IGPs (I’m an enterprise guy, so no IS-IS comments, please.), I thought I’d try to describe the basics of advertising IPv6 routes over BGP. Yet again, we’re not going to do any route manipulation or change any of the 948284928 BGP attributes. We’re just trying to get routes exchanged.
A few hours ago, the last of the IPv4 addresses were allocated by IANA. Now’s the time to learn more about IPv6! Yesterday, I posted about EIGRP for IPv6, so I think I’ll continue the trend by introducing OSPFv3, which is the IPv6 implementation of OSPF
I’m not going to go all out like Jeremy over at Packetlife.net has, but I’m going to start to discuss a few IPv6 topics. In time (like in September when APNIC runs out of IPv4 addresses), I’m sure I’ll ramp up the IPv6 talk, but let’s start easy and get EIGRP for IPv6 up and running.
EIGRP allows you to tag external routes. That is, any route redistributed into EIGRP can be tagged with a numeric descriptor from 0 to 4294967295.
I passed the ROUTE test today. I don’t know what I’m going to do with my evenings now.
What’s this? More IGP redistribution? Yes. Yes, it is.