3.1.1.1 RDP-UDP2 Data Transfer Operation

In the data transfer phase of RDP-UDP2 transport, the terminal client and terminal server of an RDP-UDP2 connection are treated as peers and use the same protocol. The connection between the two endpoints is bidirectional; data and acknowledgments can be transmitted in both directions independently and simultaneously. Logically, each single RDP-UDP2 transport connection can be viewed as two unidirectional connections. Both of these unidirectional connections are symmetrical, and each endpoint has both a Sender and a Receiver entity. Although the bidirectional connections operate as independent transports, it is possible to combine the Sender and Receiver packets from endpoint as an optimization to reduce the number of packets sent on the network. For example, the acknowledgment packets for the received packets can be combined with the data packets in the same RDP-UDP2 packet because they are both sent to the same endpoint. Multiple acknowledgment packets can be combined into a burst acknowledgment packet to further reduce the number of packets sent.

The RDP-UDP2 transport only supports reliable UDP mode. In this mode, any packet that has been detected as lost must be retransmitted. This transport does not include an FEC layer.