BROCADE IP PRIMER

Configuring BGPTo summarize, the peers go through this checklist:• TCP three-way handshake (Connect state) — check• You told me you were ready (OPEN), and I acknowledged (KEEPALIVE)(OpenSent state) — check• I told you I was ready (OPEN), and you acknowledged (KEEPALIVE) (Open-Confirm state) — check• We're Established! Let's start talking!Configuring BGPAs complicated as the BGP protocol is, configuring a basic BGP setup is verystraightforward. We start by telling the switch's Global config that we want touse BGP:BR-Switch#conf tBR-Switch(config)#router bgpNow, one of the very next things we'll want to do is define which AS the switchis in. Where OSPF may have interfaces in many different areas, one switch mayonly be a member of one AS. It may peer with other ASs (and often does), but itmay not be a member of more than one AS.BR-Switch(config)#router bgpBR-Switch(config-bgp-router)#local-as 12345Here, we've defined our AS as AS 12345. This is a public AS number, so wewould want to make sure we have it registered with the appropriate InternetRegistry. We could certainly have used a private number as well (which wouldrequire no registration).Configuring Neighbors (Peers)Neighbors are defined in the BGP config. You define the IP address of theneighbor, and the AS that the neighbor belongs to.BR-Switch(config)#router bgpBR-Switch(config-bgp-router)#neighbor 1.2.3.4 remote-as 731We've defined our neighbor's address as 1.2.3.4, and we've specified theneighbor's AS as AS 731. This is important, because this defines whether youare using iBGP or eBGP. The neighbor we've configured above is eBGP. Why?Because the AS number of the neighbor is different from the local AS wedefined earlier (AS 12345). The following is an example of defining an iBGPneighbor:BR-Switch(config)#router bgpBR-Switch(config-bgp-router)#neighbor 4.3.2.1 remote-as 12345Even though the command says remote-as, the AS defined is the same AS asthe local AS we defined earlier. This is an iBGP peer.You can define as many neighbors as your switch's resources will allow. Somecan be iBGP. Some can be eBGP.Brocade IP Primer 279