1.3 Overview

This document describes extensions that are made by Microsoft to the T.120 protocol set. This document also describes extensions to the S20 protocol, which is a pre-T.120 protocol that is similar to T.120. S20 is also used for backward-compatibility with older implementations.<1>

The Microsoft extensions to the T.120 protocol set, as specified in the Microsoft NetMeeting Protocol, include:

  • S20 Protocol: The S20 protocol is specific to an application-sharing session, which allows for the transmission of a screen view of a remote node's running applications.

  • NetMeeting Object Manager Protocol: The NetMeeting Object Manager provides the mechanism to coordinate object creation, deletion, and synchronization between two or more nodes within an established session. It is utilized while initially establishing a connection to bring the connecting node up to date with existing objects (such as whiteboard, chat, or application-sharing objects).

  • Chat Protocol: A protocol for communicating textual data between nodes. The Chat Protocol utilizes MCS in order to transfer textual data between peers.

  • Extensions to the T.127 Protocol: The T.127 protocol is used to transmit binary files between nodes.

  • Extensions to the T.126 Protocol: The T.126 protocol is used to transmit bitmaps and other drawing primitives to support a shared whiteboard between nodes.

The following figure illustrates the various components and their relationship to the entire NetMeeting protocol stack.

NetMeeting protocol stack

Figure 1: NetMeeting protocol stack