actly that. By adding a couple of simple commands to our HSRP configurations, we can create a design that will allow the Ethernet interfaces to failover in the result of a serial interface failure: Router A: interface fo/o ip address 192.168.100.2 255.255.255.0 standby ip 192.168.100.1 standby preempt standby track Serialo/o 10 Router B: interface fo/o ip address 192.168.100.3 255.255.255.0 standby ip 192.168.100.1 standby priority 95 standby preempt standby track Serialo/o 10 HSRP Interface Tracking On each router, we have added the standby track Serialo/o 10 command to the Ethernet interface. This command tells HSRP to decrement the Ethernet interface's priority by 10 if the Serial0/0 interface goes down. I've seen many networks where one router has a priority of 100 and the other has a priority of 90. When a tracked interface on the primary fails, this will result in a tie, which will cause IOS to assign the router with the highest configured IP address as the active router. While this may not seem like a problem with only two routers, traffic may not flow where you expect it to in this situation. Adding a priority decrement value is a very handy feature. If each router had three links to the Internet, for instance, you could decrement the priority by 3 for each tracked interface. In our example, if one link went down, Router A would remain active, but if two serial links went down, we would decrement its priority by a total of 6, bringing it down to 94; this would be lower than Router B's priority of 95, SO Router B would become the active router. In other words, with two routers, each containing three links to the Internet, the one with the most serial links up would become the active router (of course, a router or Ethernet interface failure would still affect the routers in the same way as the basic example). When HSRP Isn't Enough HSRP is an awesome tool, and coupled with interface tracking, it can be the means for near-total redundancy. There are situations, however, where HSRP is not enough. The example 