Transparent interception and multicast mode
To configure Content Gateway to run in multicast mode, you must enable multicast mode and specify the multicast IP address in the Content Gateway manager.
Important: GRE packet Forward/Return method cannot be used with multicast mode.
In addition, you must set the multicast address on your routers for each service group being intercepted (HTTP, FTP, DNS, and SOCKS). The following procedure provides an example of how to set the multicast address for different service groups on a WCCP v2-enabled router.