In transparent mode, the packets for accelerated connections must pass through the target appliance, much as they do in appliance-to-appliance acceleration.
The plug-in is configured with a list of appliances available for acceleration. It attempts to contact each appliance, opening a signaling connection. If the signaling connection is successful, the plug-in downloads the acceleration rules from the appliance, which sends the destination addresses for connections that the appliance can accelerate.
Whenever the plug-in opens a new connection, it consults the acceleration rules. If the destination address matches any of the rules, the plug-in attempts to accelerate the connection by attaching acceleration options to the initial packet in the connection (the SYN packet). If any appliance known to the plug-in attaches acceleration options to the SYN-ACK response packet, an accelerated connection is established with that appliance.
The application and server are unaware that the accelerated connection has been established. Only the plug-in software and the appliance know that acceleration is taking place.
Transparent mode is often used with VPNs. The CloudBridge Plug-in is compatible with most IPSec and PPTP VPNs, and with Citrix Access Gateway VPNs.
The following figure shows packet flow in transparent mode. This packet flow is almost identical to appliance-to-appliance acceleration, except that the decision of whether or not to attempt to accelerate the connection is based on acceleration rules downloaded over the signaling connection.