The RDP protocol has become more thin and more functional over the years. With the introduction of Microsoft Windows Vista and Windows Server codenamed “Longhorn”, the RDP protocol is becoming more intelligent on bandwidth as well. In the past, connections over a Terminal Server RDP share the available bandwidth unbiased with multiple applications (for example video, clipboard, printer output etc) that send data over the connection from server to client. On a low bandwidth connection these applications compete for available bandwidth. As a result, important graphics data, such as the location of a window the user moves on the desktop, has to compete with data transmitted in the background, like a print job or a file copy. This problem manifests itself most severely when printing a large document over a low bandwidth connection. The printer data competes for available bandwidth with the video rendering, thus deteriorating the graphics rendering significantly.

Vista (and Longhorn Server) fixes this by introducing a simple scheme wherein a fixed percentage of bandwidth is allocated to video, and the rest goes to virtual channel traffic (this means all kind of redirections). By default this allocation is 70% for Video and 30% for virtual channel data, meaning when bandwidth usage is under pressure video data is guaranteed to get 70% of the available bandwidth.

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