This article describes the behavior of Server-down-option in web proxy forwarding.
Scope
FortiGate.
Solution
Under web proxy forwarding server configuration, ‘Server Down Action’ has the following options: ‘Block’ or ‘Use Original Server’.
In the following example, FortiGate is a downstream/child proxy that listens to computer web sessions in port 8888.
It then redirects web proxy sessions to 10.150.4.151 in port 9999 (upstream/parent proxy).
Note:
Incorrect port 9900 has been set to simulate a failed connection to the upstream proxy.
When set to ‘Block’, if the upstream/parent proxy fails to respond properly, the downstream proxy (FortiGate) will return 504 to the computer:
When set to ‘Use Original Server’, if the upstream/parent proxy fails to respond properly, the downstream proxy (FortiGate) will use its internet gateway to reach the destination server.
