1.6 Applicability Statement

The Remote Desktop Protocol: USB Devices Virtual Channel Extension is designed to run within the context of a Remote Desktop Protocol (RDP) virtual channel established between a client and server. This protocol is applicable when any local client USB devices are to be accessible (redirected) in the remote session hosted on the server.

Device drivers and applications have to meet the following requirements if they are to be redirected:

  • This protocol is not intended for use with devices that require quality-of-service guarantees (because the I/O is sent over a network, there is no guarantee about the timeframe for delivering the I/O to and receiving it from the device).

  • For redirection to operate properly using this protocol, all communication between devices and applications are routed through the I/O routines supported by device drivers. Communication cannot be routed by any other means, such as shared memory, the registry, or disk files.

  • This protocol redirects the following operating system-specific I/O calls: Read, Write, and IOControl. Communication between the device driver and the application cannot be anything other than these basic calls. If there is any other I/O, the device cannot be redirected using this protocol hence the device will be treated as any other device attached to the client and this protocol will not be involved in any means.