BROCADE IP PRIMER

SummarySummary• BGP is the standard routing protocol for the Internet• BGP is a path vector routing protocol• BGP is both an IGP (iBGP) and an EGP (eBGP)• An autonomous system (AS) is a collection of routers that are all administeredby the same entity• Multihoming is providing more than one entrance and exit link for your AS(e.g., peering with more than one Internet Service Provider)• A Stub AS is an AS that only has one entrance and exit link• A confederation is a collection of Stub ASs• In BGP, a neighbor (peer) must be manually defined• A neighbor goes through several states:— Idle - no packets have been sent or received yet— Connect - a TCP session has been attempted— Active - the TCP session failed, but the router is actively listening— OpenSent - TCP succeeded, and the router is waiting for an OPENmessage— OpenConfirm - router sends an OPEN message, and waits forKEEPALIVE— Established - routers exchange routing information• Networks must be defined; by default, BGP shares nothing• Neighbors in the same AS are automatically iBGP• Neighbors in different ASs are automatically eBGP• Use loopback interfaces with iBGP, but be sure to use “update-source”• When using iBGP, remember to use “next-hop-self” to make sure thosewithin your AS know how to get out• There's no metric conversion when using iBGP and eBGP together• When your BGP router can't be directly connected to your eBGP peerrouter, use “ebgp-multihop”Brocade IP Primer 285