Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Backup configuration

I'm trying to implement a backup solution for my Internet connection. Right now, I have all my Internet bound traffic going to my Comcast Internet connection through a PIX which is connected to my Cisco 2811 router's fa 0/1. My WAN traffic is headed out a serial T1 connection. Our Atlanta office has an Internet connection that we use as a backup. The current config goes like this.

All WAN traffic is forwarded out the WAN interface, and the default route is pointing to Comcast. A static floating route exists that points to the WAN interface, so if I unplug the fa 0/1 (router to PIX connection) all the traffic that would normally go to Comcast, is now re-routed to Atlanta and the Internet successfully. However, the problem is when I take the Comcast cable modem down, the 2811 still sees the fa 0/1 interface as up and forwards Internet bound traffic its way, which of course is now a dead end. I've looked at HSRP, but it seems like that wouldn't work here since it involves making 2 gateways appear as one. I want Internet bound traffic to head toward Comcast unless it is down, and of course I can't send WAN traffic toward Comcast. Does anyone have any ideas for this scenario?

Thank you,



Re: Backup configuration

You can Use RTR and Track feature to monitor if Comcast gateway is down.

ip route track 9

##### Default route via Comcast network.

ip route serial 0 150

##### floating static route.

rtr 1

type echo protocol ipIcmpEcho

timeout 1000

frequency 3

threshold 2

rtr sched 1 start-time now life forever


track 9 rtr 1 reachability

Here is a link to more info on the commands.


PS: please remember to rate helpful posts.

New Member

Re: Backup configuration

I only got to test this today, but wanted to say it works great. Thank you very much.


CreatePlease login to create content