VNS Video-Over-IP Guidelines

What is H.323 (Video Over IP)? H.323 is an umbrella recommendation from the International Telecommunications Union (ITU), setting standards for multimedia communications over LANs that do not guarantee quality of service. H.323 is part of a larger series of ITU-T communications standards for voice, data, and videoconferencing.  The first H.323 specification was approved in 1996, and subsequent versions have increased functionality. Using H.323 standards, a network manager can restrict network bandwidth used for applications like videoconferencing. H.323 defines five major components for a network-based communications system: terminals, gateways, gatekeepers, and multipoint control units (MCU). Voice, video, and data are all supported across this common four-part architecture. * Terminals or (Endpoints) are the video conferencing systems on LANs that support voice, video and data. H.323 terminals must also support H.245, which is used to negotiate channel usage and capabilities. Three other components are required: Q.931 for call signaling and call setup; Registration/Admission/Status, which is used to communicate with a gatekeeper; and support for sequencing audio and video packets.   *A device called a codec accomplishes video processing in the video terminal.  Codec is short for Coder/Decoder.  A typical video conferencing system is comprised of a codec, cameras, audio system, video monitors, and network interface.   * Gateways are optional in an H.323 conference. Gateways provide many services, the most common being translation between H.323 conferencing endpoints and other terminal types. The ITS Video Network Services gateways bridge the NCIH H.320 network to the new H.323 IP network. * A gatekeeper provides call control services to registered endpoints. In many ways, an H.323 gatekeeper acts as a virtual switch, and it performs address translation and manages bandwidth. The collection of all terminals, gateways, and MCUs managed by a single gatekeeper is known as an H.323 Zone. * MCUs provide the capability to bring three or more parties on a single voice or video call.