About the Transparent Bridge Mode
The Transparent Bridge mode is one of the transparent network modes you can configure for the proxy functions of a Secure Web Gateway appliance if you do not want to use an explicit (direct) mode.
In this mode, the clients are unaware of the appliance and need not be configured to direct their web traffic to it. The appliance is usually placed between a firewall and a router, where it serves as an invisible bridge.
For the high-level steps that are needed to configure this mode, see Configure the Transparent Bridge Mode.
The following diagram shows a Transparent Bridge mode configuration with a Secure Web Gateway appliance placed between a firewall and a router.