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Backup async interface


I have a network which connects in a star configuration. I have one central router with 9 outer routers connecting in. The outer routers have 2 asyncs, the line connecting these routers to the central router has 2 presentations (on-line and off-line). I have configured async2 to 'backup' async 1. No problems this all works fine.

At the central router we have an N+1 configuration. This means if the line from any of the outer routers fail, it can do a N+1 switch to the spare '+1' interface. Switching done by other means beyond the scope of this discussion.

I want to try and get the N+1 async interface on the central router to backup ANY of the outer routers. Obviously it can only do the first one which fails if we had multiple faliures. But hey, its an N+1 system!

The current IP config at the moment is a basic point to point PPP, async 1 and 2 on the outer router have and address each and so does the central routers async.

Although I havent tried I presume you can't configure >1 interface on a router in the same subnet.

I have configured ip un-numbered on all asyncs including the N+1. This worked well. I want to try to do this another way. I have a feeling Cisco Works/Open view isn't going to like un-numbered interfaces if i roll this out.

I have also tried creating an async group and then backup to a single async, but you can't give the group an IP address.

Any commenst welcome.


Re: Backup async interface

I am not sure if I understand your question correctly, but just wanted to point out that there other ways to backup links like 'dialer-watch' and floating static routes apart from the 'backup interface' command. Check if those mechanisms will be able to help you.