Alternate route

[manish-young]

(router1)-----------------(router2)------------------(router3)

router 1 have a serial link to router2 backed up by isdn line, so do router 2 to router3 . is it possible to make router3 dial router 1 if link between router 2 and router 1 is down

with regards

manish young

[rwiesmann]

Hi

Do you intend to work with backup interface?

If you have a dynamic routing protocol in place you could add a static route with a higher admin distance which points to the isdn. So as soon as the route from the dyn. Routing Protocol disappears the static route will take over. If there is data to forward for that network the isdn line will go up.

In my opinion you should work also with dialer interfaces.

Hope that helps

Roger

[vcjones]

Sure you can. The easiest way is with dialer watch monitoring a route which router 2 can only learn from router 1. You can also do it with dial on demand routing (you should not use dialer watch with IOS preleases prior to 12.1(7) so you may not have a choice). There are all sorts of ways to play around with dial backup, see for example the scenario "Spoke Dialing Around Loss of Hub Internal Connectivity" starting on page 368 of my book (High Availability Networking with Cisco) for an equivalent setup to your request. The configurations are on my web site.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com