Squid server to use other Proxy (cache)

If you want Squid to be part of a hierarchy of proxies or want Squid to fetch content from another proxy

cache_peer proxy.isp.com parent 8080 0 no-query no-digest ever_direct allow all

For Multiple parent

cache_peer proxy.isp1.com parent 8080 0 no-query no-digest default

cache_peer proxy.isp2.com parent 8080 0 no-query no-digest

Multiple parents with weight:

cache_peer proxy.isp1.com parent 8080 0 no-query no-digest weight=1 

cache_peer proxy.isp2.com parent 8080 0 no-query no-digest weight=2

Multiple parents with round-robin:

cache_peer proxy.isp1.com parent 8080 round-robin no-query

cache_peer proxy.isp2.com parent 8080 round-robin no-query

cache_peer proxy.isp3.com parent 8080 round-robin no-query

In above examples proxy.isp1.com, proxy.isp2.com and proxy.isp2.com are other cache servers