We currently have a single Cisco 1841 router that has a few dozen serial subinterfaces(16K CIR each) that connect to remote locations. The traffic going to each location is extremely light (mostly just ICMP and SNMP). Of course, all of this is off the serial interface. The links are point-to-point frame relay, which is provided by at&t.
The ethernet interface is connected to our primary distribution switch (Cisco 3560G). We have a few servers on our LAN that uses this interface as their default gateway.
Both routing and NAT are all static (and must remain that way).
I recently discovered that we have a 1841 sitting in our closet that is doing nothing, and I was told to implement it into our network as a possible backup to our router that is currently in production.
Ideally, I would like to have this backup 1841 connected to our backup distribution switch (Cisco 3560G). I would like to have this backup 1841 automatically take over if the primary 1841 goes down.
What is the best way to go about doing this with my scenario?
I was thinking about incorporating HSRP on both routers, and using the virtual IP as the default gateway for our servers. However, I do not know how exactly that will work on the WAN/frame relay interfaces. My guess is that I will have to have at&t come out here and provision another line for us, and assign new DLCIs for the backup router? That of course would involve configuring backup interfaces and floating static routes on our remote site routers?
I am hoping to do something with this backup router, other than having it sit there powered off as a cold fail-over.