Background: I have 2 routers; 3640 and 3660 connected to the same LAN, each of these routers provides access to remote sites using 1750's via primary Kilostream links with ISDN BRI links as backup. Each 1750 has serial interface providing Kilostream conncetion and BRI interface providing ISDN backup. Each of the 3600 routers has serial E1 interface providing 64K to multiple remote locations and PRI interface providing multiple dialup access for back up. So for example each remote site has a Kilostream link to one 3600 router and the ISDN BRI is connected to the other 3600 router.
Problem: My problem is that on the 3600 routers configuring the serial interface so that when a kilostream channel goes down the router will route the packets via the PRI interface on the alternate router. I have tried setting up the backup interface using the ethernet port on the router and then using static routes to route packets via the LAN. However this only resulted in the router locking me and the rest of the network out.
I am sure that someone somewhere has done this before, and without doubt the solution will incredibly easy and obvious, but I am prepared to humble myself in the interest of learning.
Thanking you in anticipation