In the last week of 2017 I kicked off the project I wanted to start for quite a while - live streaming about network programmability, automation and Python on Twitch.
I could have made it a New Year’s resolution, but there isn’t a better time to do something than now. So why wait?
An opportunity presented itself spontaneously. My RouterGods colleague Judson is currently preparing for CCIE R&S and of course, like any decent CCIE candidate, he is labbing a lot. Recently he started creating his own big lab with a massive number of devices (65+) in the network emulator EVE-NG, but unfortunately EVE-NG can’t handle more than 64 nodes properly. He wanted to switch to GNS3, but encountered some problems there as well. Together we resolved those, and he was ready to start rebuilding his EVE-NG lab in GNS3. Anyone who has ever created a big lab in any network emulator knows how much time it takes to connect everything together and to prepare the base configurations with IP addressing. When he mentioned this to me I immediately started thinking about simplifying this tedious process by writing a topology converter from EVE-NG to GNS3 in Python. I thought it would be an interesting experience to do the whole process on the stream live. So I offered Judson my help and this is how my first project on the stream was born.
This is the first post in a series about routing protocol EIGRP. Today we will deep dive into how metric is calculated in EIGRP classic mode.
EIGRP is a distance-vector routing protocol, but what does it really mean? How does a distance-vector routing protocol differ from link-state? Distance-vector is also referred to as “routing by rumor”. It means that a router makes its decision based on the metrics reported by his neighbors.
This is unlike a link-state routing protocol where every router in an area (OSPF) or level (IS-IS) knows the whole topology for this area/level and calculates the best path locally using the shortest-path algorithm (Dijkstra). Because routers have the same information, it results in a consistent choice of the best path.