1.3.1 RDP-UDP Protocol
The Remote Desktop Protocol: UDP Transport Extension Protocol has two distinct phases of operation. The initial phase, UDP Connection Initialization (section 1.3.2.1), occurs when a UDP connection is initialized between the terminal client and the terminal server. Data pertaining to the connection is exchanged and the UDP connection is set up. Once this phase is completed successfully, the protocol enters the UDP Data Transfer (section 1.3.2.2) phase, where Coded Packets are exchanged.
The protocol can operate in one of two modes. The operational mode is determined during the UDP Connection Initialization phase. These modes are as follows:
RDP-UDP-R or "Reliable" Mode: In this mode, the endpoint retransmits datagrams that have been lost by the underlying network fabric.
RDP-UDP-L or "Best-Efforts" Mode: In this mode, the reliable delivery of datagrams is not guaranteed, and the endpoint does not retransmit datagrams.
The connection between the endpoints is terminated when either the terminal client or terminal server terminates the connection. No protocol-specific messages are exchanged to communicate that the endpoint is no longer present.