Failsafe proxy hierarchy configuration

Hi,

I wonder whether the following szenario is possible:

We have more than one WAN lines to different Internet providers. On our
end each line is connected to its own Squid proxy server (running Squid
1.0.16). These local servers are normally using remote parents at the
other end of the WAN lines, for instance the proxy servers of the
Internet providers. This would make it possible to detect the failure of
a WAN line (the remote parent just doesn't answer anymore and is
therefore considered offline). Direct accesses over this very WAN line
aren't possible then, either. So the local proxy at the defective line
needs a fallback parent.

The easiest solution would be that the local proxy servers all use each
other as parents, but with a weight value that strongly prefers the
remote proxies at the other end of the WAN lines as long as they are
available. As far as I can imagine, this should work. However, what
happens if all WAN lines break down? Wouldn't the local proxies forward
their requests back and forth in a loop, using each other as parents?

So, I would like to know whether Squid contains code that detects and
prevents those parent proxy loops, or whether I have to take care of
that in the config file (if that is possible at all).

Does anyone know what to do or has a better idea how to set up a
failsafe proxy hierarchy using multiple WAN lines?

Thanks.

      Uwe

-- 
Uwe Doering
Interactive Networx
EMail: gemini@unlisys.NET