Best configuration for fail-over?

Hi there

We are going to be altering our Internet connectivity topology in the near
future and I'm trying to figure out the best way to have Squid configured to
deal with it.

Soon we will have two separate Internet links via different networks, both
of which will be our Squid "parents". What I want is for our proxies to only
talk exclusively to one parent until that parent reports it can't see the
Internet anymore (due to it's WAN link going down), at that stage our squid
servers should start talking to the other network's parent instead.

Should I use the 'default' keyword for a last-resort parent? What I don't
know is when is a parent defined as being "down"? Is it when it stops
responding (no good for what I need) or is it when it says it can't connect
to the sites you are after...?

Thanks

-- 
Cheers
Jason Haar
Unix/Network Specialist, Trimble NZ
Phone: +64 3 3391 377 Fax: +64 3 3391 417