two outgoing gateway and two parent proxy with load balancing in squid proxy

[spaceman <spacephai@xxxxxxxxx>]

Dear Sir or Madam,

	Firstly i would like to apologize for my poor english

          I want to load balance two isp connection with one linux
squid proxy server.Load balancing and failover is ok using shorewall
firewall.My network setup is here


                 eth0  is for LAN

                 eth1   is for A internet connection       It use
Parent-A upstream parent proxy server

                 eth2   is for B internet connection       It use
Parent-B upstream parent proxy server

            I user Fedora Core 10 and Shorewall Firewall (www.shorewall.net) .

           Shorewall automatically load balance and failover outgoing
internet gateway.

            Now i want to set up squid proxy server.

            My problem is that each internet connection has seperate
parent proxy.

           So i want to route,match or map A internet gateway request
to Parent-A upstream parent proxy server  and B internet gateway
request to Parent-B upstream parent proxy server in squid proxy.

                   I think i must be use
                      cache_peer
                      cache_peer_access
                       tcp_outgoing_address
                                 but no sure .i have test so many
times but fails

                        Any help would be great.With best regards