It seems that you want to use nearby proxy (ISP proxy) to save bandwidth or to improve speed. If so.. then you need to setup cache peer for hierarchy configuration.
For example consider following option (squid.conf):
Code:
cache_peer cache.isp.cache.com parent 3128 3130 default
Where,
cache.isp.cache.com ISP cache
parent (see url for more info
http://squid.visolve.com/squid/squid24s1/neighbour.htm)
3128 Proxy port
3130 ICMP port
proxy-only (options can be found at above url or in squid.conf)
But your ISP must provide the access to ICMP port 3130 (or whatever used on that squid proxy).
If you have more questions reply back.