One squid instance, two WAN links, how to failover from primary to secondary link?

[Thomas Harold <thomas-lists@xxxxxxxxxx>]

In an instance where you have a single instance of squid running on a 
system with two WAN links, how would you configure things so that squid 
will default to proxying all traffic from the LAN to WAN#1, but fallback 
(failover) to WAN#2 if WAN#1 is down?

We're not interested in load-balance between the two WAN links as WAN #2 
is very slow compared to WAN #1.

Is this simply handled by changing the default gateway of the server 
using the "ip route" commands when we detect that WAN#1 is down?