BACKUP INTERFACE (ADDITIONALY POSTED ON WAN ROUTING AND SWITCHING)

[derekgroome]

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

Derek Groome

[tepatel]

First of all you need to decide which site will dialout on bri line when the kilo stream went down. In your case, remote sites 1750 should dial to 3600 when primary connection went down.

Now there are multiple ways to configyre a backup scheme. Following is the link which will help you to evaluate which scheme is the best one for your network.

http://www.cisco.com/warp/public/123/backup-main.html

Above link has a sample config for various scheme too.

I am not sure which interface is the primary On 1750, you can configure backup interface command to work when the kilostream went down..