  I solved the problem by adding static routes to the firewall.   Since ISA doesn’t do routing I added them at the OS layer so the server could then see the subnets which resulted in the clients on the subnets seeing the firewall.  
  I have a powerconnect 6224 router configured with 3 subnets. 10.10.10.0 10.10.11.0 10.10.12.0 Our firewall has an internal ip address of 10.10.10.254 Its an ISA firewall on a windows 2004 server. Since we can only assign one default gateway to our server it has been assigned a default gateway on the external Interface. So the internal interface has no default gateway! As a result the only clients than can route to the internet are those on the 10.10.10.0 How can I route the other subnets to the firewall (10.10.10.254) ? Can I add static routes to do this? If so how? Regards, Stephen     
Adding routes to a firewall with no default gateway