The Border Gateway Protocol 4 specification (RFC 4271) requires that iBGP peers be fully meshed; that is, every iBGP peer must have a connection to every other iBGP peer. A full mesh of iBGP peers does not scale well to large AS, which can have hundreds of iBGP routers. To scale well in a large AS, two enhancements have been developed for BGP:

• BGP Confederations (RFC 3065)
• Route Reflection (RFC 2796)