PPP dialup as backup to high speed

[jrepetto]

Does anyone know of a Linux script or other mechanism to allow a PPP dialup connection act as a backup for an ADSL connection? Hopefully something that would autodial if the "main" connection failed, would hangup after some idle time, and only dial out again when the main connection was not working. This is for a Linux router machine.

This *must* have been answered before, but I did not find it. Please excuse me if this has been answered too many times already.

Jean-Claude

Note : This question has already been asked by Brad on usenet, but there was no answer ... Since I have exactly the same problem, and I am using Gentoo Linux, I try here.

[jamapii]

I thought about this before, but never implemented it.

I think a way to approach this would be to get the backup dialup connection working as well as the main connection. Then, have a cron job that checks the main connection in short intervals. If it goes down, start the backup connection, but keep the main connection trying and watch it. If it goes up, end the backup connection.

This should preferrably be a small set of scripts with as little as possible modification to anything else. The main connection, the backup connection and the scriptset that controls what is used should be separate entities to keep it maintainable.

Maybe it won't be done because nobody has the time and the pressing need for it and also happens to be a *ix user.