1.3.2 RDP Channels and Multitransport Connections

The main RDP connection is encapsulated in the Transmission Control Protocol (TCP) ([MS-RDPBCGR] section 2.1). The I/O channel ([MS-RDPBCGR] section 3.2.1.3 and 3.3.1.3) and the optional message channel ([MS-RDPBCGR] sections 3.2.1.3 and 3.3.1.5) are encapsulated within the main RDP connection and are used to transport core RDP PDUs, input and graphics data. In addition to these two channels there is a collection of negotiated static virtual channels ([MS-RDPBCGR] section 1.3.3). One of these static virtual channels, named "DRDYNVC", multiplexes a collection of dynamic virtual channels ([MS-RDPEDYC] sections 1, 2 and 3).

Multitransport connections run over a separate transport protocol to the main RDP connection and multiplex a collection of selected dynamic virtual channels.

The following figure illustrates the hierarchy and encapsulation of RDP channels and transports.

Figure 2: RDP channels and transport