Chapter 23 WAN Optimization, Web Cache, Explicit Proxy, and WCCP : FortiGate WCCP : WCCP service groups, service numbers, service IDs and well known services : Other WCCP service group options : Server configuration options
  
Server configuration options
The server configuration must include the router-id, which is the WCCP server IP address. This is the IP address of the interface that the server uses to communicate with WCCP clients.
The group-address is used for multicast WCCP configurations to specify the multicast addresses of the clients.
The server-list defines the IP addresses of the WCCP clients that the server can connect to. Often the server list can be the address of the subnet that contains the WCCP clients.
The authentication option enables or disables authentication for the WCCP service group. Authentication must be enabled on all servers and clients in a service group and members of the group must have the same password.
The forward-method option specifies the protocol used for communication between the server and clients. The default forwarding method is GRE encapsulation. If required by your network you can also select to use unencapsulated layer-2 packets instead of GRE or select any to allow both. The return-method allows you to specify the communication method from the client to the server. Both GRE and layer-2 are supported.
The assignment-method determines how the server load balances sessions to the clients if there are multiple clients. Load balancing can be done using hashing or masking.