As keith points out you need to disable the default compression in RDP, or at best you can set the encryption to low which will encrypt data from client to server (i.e. logon) but data returned to client is in the clear. We get upto circ 60% for RDP occasionally a little higher and at worst 50%. Be ware that as Win2003 and 2008 arrive using the RDP 5.2 or 6.0 client allows you to use SSL to encrypt the data rather then propietary encryption we can better interact with out 5.5 code and provide a more comprehensive solution.
Danny Jump Technical Marketing Manager - Access and Acceleration Business Unit
Just a quick add-on on how to do that on your Windows server: To change the encryption level, you must be an administrator. In Programs | Administrative Tools, select Terminal Services Configuration and perform these steps: 1. In the left console pane, select Connections. 2. In the right details pane, right click RDP-TCP and select Properties. 3. Click the General tab. 4. Under Encryption level, select the desired level in the drop down box and click OK.
• High: encrypts both the data sent from client to server and the data sent from server to client using a 128 bit key. • Medium: encrypts both the data sent from client to server and the data sent from server to client using a 56 bit key if the client is a Windows 2000 or above client, or a 40 bit key if the client is an earlier version. • Low: encrypts only the data sent from client to server, using either a 56 or 40 bit key, depending on the client version. Useful to protect usernames and passwords sent from client to server.
And, as Danny said if the PC-Clients are using RDP 5.2/6.0, you can configure the Windows 2003/2008 servers "Security Layer" (in the same General tab as "Encryption Level") to use SSL encryption ("Negotiate" option). With our SSL acceleration (in 5.5 release) the WX will be able to accelerate that traffic even with encryption is at High level.