Help with static routes

[Chuck Smith]

OK I have a 3660 router connecting all my outer offices to the main office. I have to servers running microsoft ISA server as my internet firewalls. Each server has its own IP address. In my router have the static route

ip route 0.0.0.0 0.0.0.0 10.0.0.93

this points to one of the ISA servers.

What I want to do is point the router to the other as well but to only use it when the main router fails. As I am reading about how static routes are handle the router balances request between the 2 default routes. How do you force the router to only use the second route as a backup?

[thisisshanky]

I guess, what you want is to point the router (3660) to one of the ISA firewall server, and use the second ISA firewall server as backup.

For this,

give

ip route 0.0.0.0 0.0.0.0 10.0.0.93

ip route 0.0.0.0 0.0.0.0 10.0.0.94 2

Where 10.0.0.93 is ip add of first ISA and 10.0.0.94 is that of second ISA Server

The second route has administrative distance of 2 which is higher than the first route. Only first route will be in routing table. The second route kicks in when first server becomes inaccessible.

[Chuck Smith]

Man you know I just read that a second ago and was going to try it. If it works like you say it does then I am in biz. Thanks for the prompt reply. I will let you know if it preforms and desired.

Thanks,

Chuck

[vcjones]

This won't work if the 3660 and firewall servers are both on the same Ethernet, because the 3660 will only declare the 10.0.0.93 server unreachable when the router's Ethernet interface goes down, in which case it would not be able to reach the backup server either.

Automatic fallback in this scenario requires running a routing protocol so that the router can detect loss of communication with the firewall. For example, with PIX firewalls, you can turn on RIP between the firewalls and the 3660 and advertise a default route (preferably one that is conditional on the firewall being able to actually communicate with the ISP).

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com