Chapter 9 - Convergence Standards and Protocols

Abstract

This chapter discusses various aspects of convergence standards and protocols. An H.323 gateway is an end point on the network that provides for real-time, two-way communications between H.323 terminals on the Internet Protocol network and other International Telecommunication Union terminals on a switch-based network, or to another H.323 gateway. It performs the function of a “translator,” performing the translation among different transmission formats. Terminals are the LAN client end points that provide real time, two-way communications. All H.323 terminals have to support H.245, Q.931, Registration Admission Status (RAS), and Real Time Transport Protocol (RTP). H.245 is used for allowing the usage of the channels, Q.931 is required for call signaling and setting up the call, RTP is the real-time transport protocol that carries voice packets, while RAS is used for interacting with the gatekeeper. Gatekeeper may choose to complete the call signaling with the end points and may process the call signaling itself. It is found that the RAS channel is also used for the transmission of Admissions, Bandwidth Change, Status, and Disengage messages.