BROCADE IP PRIMER

Redundancy: Virtual Router Redundancy Protocol (VRRP)VRRP allows us to configure a virtual IP address that both routers (in thisexample) can share. Only one will answer for it at a time. The two routers willsend “hello” messages back and forth to each other. When the active routerfails, the other will assume the responsibility. Let's see how we would set thisup.Configuring VRRPTo set up VRRP, you start out like you're setting up a routing protocol. You startby defining VRRP in the Global config:BR-RouterA#conf tBR-RouterA(config)#router vrrpNext, you need to configure the interface on Router A:BR-RouterA#conf tBR-RouterA(config)#int e 1BR-RouterA(config-if-e1000-1)#ip address 10.1.1.11/24BR-RouterA(config-if-e1000-1)#ip vrrp vrid 1BR-RouterA(config-if-e1000-1-vrid-1)#owner track-priority 20BR-RouterA(config-if-e1000-1-vrid-1)#track-port e 4BR-RouterA(config-if-e1000-1-vrid-1)#ip-address 10.1.1.11BR-RouterA(config-if-e1000-1-vrid-1)#activateLet's step through these a bit. First off, we've got to give e 1 an IP address (thediagram shows that it was configured already, but I put it in there just toremind you it was there). The next thing we do is define the Virtual Router ID(VRID). We've given the VRID a number “1” arbitrarily. This is just to identifythis specific VRID. A single interface could have more than one VRID.Next, we defined this router as the owner. In VRRP, the owner is the device thatanswers for the address. All other devices configured with the same VRID aremerely backups, waiting for the opportunity to take over, should the needarise. We've also specified a “track-priority.” By default, the owner of a link hasa priority of 255 (priority is an 8-bit number). The track-priority (in VRRP) is thepriority number that the router takes on, if the primary link (e 1 in this link) or atrack-port fails. In our example, the track-priority is 20.The next line, “track-port e 4” is a Brocade enhancement to the VRRP protocol.It allows you to track the failure of a port other than the primary port. Look atthe diagram again. If e 1 of Router A went down, we'd want VRRP to fail over.That's obvious. But what if e 4 on Router A went down? The e 1 interface wouldstill be up, but the router's function would be useless. This way, we've toldVRRP to track e 4. If it goes down, the priority changes (and we'll likely configureRouter B with a higher priority than 20; we'll get there in a minute).Next, we have to give it the virtual IP address. Notice that we use the keyword“ip-address” (with a hyphen). More importantly, notice that the IP address isthe exact same IP address we assigned to e 1. With VRRP, the virtual addressmust be the same address as the owner's physical address.Brocade IP Primer 311