1.3 Overview

The sequence of messages exchanged by the Remote Desktop Protocol: Virtual Channel Echo Extension is described in the following figure. The messages exchanged in this diagram are strictly sequential.

The echo message sequence

Figure 1: The echo message sequence

The terminal server originates all Echo Request protocol data units (PDUs) (section 2.2.1). Each Echo Request PDU sent to a terminal-server client contains a sequence of bytes ([MS-DTYP] section 2.1.2) that is sent back to the server in an Echo Response PDU (section 2.2.2).