Grouping forwarding servers and load balancing traffic to the servers

You can add multiple forwarding servers to a forwarding server group and then add the server group to an explicit policy instead of adding a single server. Forwarding server groups can only be created from the FortiProxy CLI using the config web-proxy forward-server-group command but can be added to policies from the GUI (or CLI).

When you create a forwarding server group, you can select a load balancing method to control how sessions are load balanced to the forwarding servers in the server group. Two load balancing methods are available:

• Weighted load balancing sends more sessions to the servers with higher weights. You can configure the weight for each server when you add it to the group.
• Least-session load balancing sends new sessions to the forwarding server that is processing the fewest sessions.

When you create a forwarding server group you can also enable affinity. Enable affinity to have requests from the same client processed by the same server. This can reduce delays caused by using multiple servers for a single multi-step client operation. Affinity takes precedence over load balancing.

You can also configure the behavior of the group if all of the servers in the group are down. You can select to block traffic or you can select to have the traffic pass through the FortiProxy explicit proxy directly to its destination instead of being sent to one of the forwarding servers.

Example

The following example adds a forwarding server group that uses weighted load balancing to load balance traffic to three forwarding servers. Server weights are configured to send most traffic to server2. The group has affinity enabled and blocks traffic if all of the forward servers are down.

config web-proxy forward-server
    edit server_1
        set ip 172.20.120.12
        set port 8080
    next
    edit server_2
        set ip 172.20.120.13
        set port 8000
    next
    edit server_3
        set ip 172.20.120.14
        set port 8090
    next
end

config web-proxy forward-server-group
    edit New-fwd-group
        set affinity enable
        set ldb-method weighted
        set group-down-option block
        config server-list
            edit server_1
                set weight 10
            next
            edit server_2
                set weight 40
            next
            edit server_3
                set weight 10
            next
        end
    next
end