HSRP with BGP

[c.daly]

Hi,

I am planning to run HSRP and BGP on two routers. The two routers are connected to the same LAN. And each router has an ethernet type of WAN connection (some sort of DSL network) to the ISP. With HSRP, one router will be active and the other will be passive, no load balancing is required. From my understanding, I can configure HSRP to monitor the WAN (serial) interface of the active router. If it goes down, it will increase the priority value of the active router and hence force the passive router become the active one. My questions are 1)Can HSRP monitor an ethernet interface instead of a serial interface? 2) If it doesn't, I am thinking to put a direct ethernet link between the two routers. In case the primary link goes down but the active router stays active, it can still send the traffic out via the passive router. Is this workable? Thanks for your advise.

[Richard Burts]

In traditional implementation of HSRP it works better to track serial interfaces and less well to track Ethernet interfaces. The issue is that HSRP tracking needs the line protocol to go down, which is the trigger for changing the HSRP priority. On most serial interfaces if there is a failure of the connection the line protocol will go down which means that HSRP tracking works (there are some exceptions to this). The issue tracking Ethernet interfaces is that there are numerous failure modes where you lose connectivity but the line protocol stays up which means that HSRP tracking is not effective.

There is an enhancement to HSRP tracking in recent versions of IOS. This new feature is Object Tracking and it tracks reachability of remote objects (like the IP address of the neighbor on the Ethernet interface) and if the remote object is no longer reachable then it will force the line protocol down. I believe this enhancement will allow you to do what you want in tracking the relationship of the other router connected via Ethernet.

HTH

Rick