Configuring BGP BGP Overview
OmniSwitch 6800/6850/9000 Advanced Routing Configuration Guide December 2007 page 4-11
BGP Confederations
Confederations are another way of dealing with large networks with many BGP speakers. Like route
reflectors, confederations are recommended when speakers are forced to handle large numbers of BGP
sessions at the same time.
Note. This feature is not supported in the IPv6 BGP environment.
Confederations are sub ASs within a larger AS. Inside each sub AS, all the rules of IBGP apply. Since
each sub AS has its own AS number, EBGP must be used to communicate between sub ASs. The
following example demonstrates a simple confederation set up:
AS 100 is now a confederation consisting of AS 1001 and AS 1002. Even though EBGP is used to
communicate between AS 1001 and 1002, the entire confederation behaves as though it were using IBGP.
In other words, the sub AS attributes are preserved when crossing the sub AS boundaries.
Confederations are discussed further in “Creating a Confederation” on page 4-44.
AS 100
AS 1001 AS 1002
EBGP
IBGP