Drawing Layer 3 Maps on the CCIE Lab

05 May 2011 - Lab-Rat

Last time, I went over layer 2 diagramming- here’s how I diagram the layer 3 Internal Gateway Protocols (IGPs).

Drawing IGPs

I begin with a logical diagram on the layer 3 connections. I add the IP addressing scheme, and I’ll also include IPv6 as a shortcut to avoid having to draw another map. Sometimes the IPv6 is complicated enough that it justifies it’s own diagram, but about 80% of the time I can get away with one. I add loopbacks one line at a time- more than one just stack them. I don’t usually include the mask unless it’s different than the default, which is USUALLY /24- be sure to check carefully this is definitely a gotcha.

In the workbooks, you’ll see they tend to loosely outline the routing domains- if you’re lucky, they’re in color. I prefer to color the actual connections to match the IGP. I use red for OSPF, blue for RIP, and green for EIGRP. Of course feel free to develop your own color scheme, lol. I use arrows in the appropriate color for redirection as well.
CCIE Lab Layer 3 Diagram

Drawing BGP

Here’s how I draw BGP if including it on the IGP layout would be too cluttered. Boxes for the autonomous systems, and some folks do, but I don’t label iBGP and eBGP- if it’s in the AS, then it’s iBGP. Including the interfaces helps me keep the update sources straight- if it’s a loopback and eBGP, then I remember to add multihop.
CCIE Lab Layer 3 BGP Diagram