CCDE – BGP Confederations
Introduction
BGP Confederations are one of two tools a network designer has to work around the full mesh requirement of iBGP. BGP confederations are defined in RFC 5065 which obsoletes RFC 3065. This is how the RFC defines BGP confederations:
This document describes an extension to BGP that may be used
to create a confederation of autonomous systems that is
represented as a single autonomous system to BGP peers
external to the confederation, thereby removing the “full mesh”
requirement. The intention of this extension is to aid in
policy administration and reduce the management complexity
of maintaining a large autonomous system.
The other option to work around the full mesh requirement is of course route reflection.
BGP Confederation Operation and Use Case
BGP confederations work by having several sub AS or member AS that are used internally to divide the BGP domain. From the outside they all look like they are the same AS though. By breaking up the BGP domain, there will be less iBGP peerings which makes the full mesh requirements easier to handle. Do note though that it’s entirely possible to use route reflection within a member AS to combine the two technologies.
BGP confederations made a Continue reading