BROCADE IP PRIMER

Chapter 13: Border Gateway Protocol (BGP)Also, like OSPF, you can define an MD5 key for authentication. This key mustbe defined the same on both sides, otherwise, the peering will never establish.BR-Switch(config)#router bgpBR-Switch(config-bgp-router)#neighbor 1.2.3.4 remote-as 731BR-Switch(config-bgp-router)#neighbor 1.2.3.4 passwordSomethingLater, if you show the running config, “Something” will be replaced by anencrypted hash.Advertising RoutesI implied this earlier, but to share routes via BGP, you must define which routesyou want to share. You do so using this command:BR-Switch(config)#router bgpBR-Switch(config-bgp-router)#network 1.2.3.0/24Notice that you have defined only one network: 1.2.3.0/24. This will be theonly route passed to your eBGP peer. Also, if your are peering with an InternetService Provider, you will find that you will need to tell them which routes youare advertising. They've learned long ago that there are people who will try toadvertise network ranges which they do not own, or they may make a mistakein the configuration. Coordinating with the ISP provides an extra checkpoint.When configuring an iBGP peer, you will share all of the eBGP routes learnedto your iBGP neighbors by default. No extra configuration is needed.When routes are sent, they include the network address, the AS number (thatthe network belongs to), the next-hop (the IP address of the router you wouldsend to; usually the IP address of your router, the router that advertised theroute), and the route origin (which would be the AS path up to this point; if yourrouter is originating the route, it would include only your AS number). For example,we are advertising network 1.2.3.0/24. When this route is passed to oureBGP peer, the neighbor will see:• Network address — 1.2.3.0/24• AS number — 12345• Next-hop — • Route Origin — 12345Loopback Interfaces (iBGP)Just as in OSPF, it's very wise to use a loopback interface for the neighboraddress. Here again, if you have multiple ways that your switch may bereached, you don't want a session to die purely because only one of your interfaceswent down. The loopback interface is always up, as long as the switch isup.280 Brocade IP Primer