VoIP Now: H.323 protocols and their applications

September 06, 2005

H.323 protocols and their applications - Part 1

H.323 is a protocol that covers the broadcast of real-time voice, video, and data over IP-based networks. H.323 is applicable to multipoint-multimedia transmissions and provides a range of services that find use in various businesses. The streams of media move along RTP/RTCP, where RTP is the carrier for the media and RTCP carries the status. H.323 is an umbrella protocol from the International Telecommunications Union (ITU). H.323 also ensures the congruence of mobile multimedia applications and different services. It comprises several protocols as explained below.

DVB: Digital Video Broadcasting (DVB) systems are supported by CATV infrastructures. DVB uses satellite, cable, and terrestrial means for the purpose of broadcasting. DVB standards were created in 1993 in Europe with the objective of unifying the framework for all delivery systems.

H.225: It is a standard used to establish a call over a Registration and it encompasses narrow-band visual telephone services as per the recommendations of the H.200/AV.120-Series. H.225 deals with managing audio and video information on a packet based network in order to facilitate services in an H.323 environment.

H.225 Annex G: It supplements the H.225.0 RAS protocol in fulfilling the needs of communication between administrative domains. It details the process of address resolution and access authorization necessary for completing calls between administrative domains. The H.225 Annex G is required because of the amount of equipment that exists in an H.323 network. It does not require a particular system architecture inside the administrative domain and it supports different call models like gatekeeper routed and direct endpoint.

H.225E: It deals with the implementation of UDP and TCP based protocols by using a packetization method, a signaling framework, and wire-protocol. It also specifies the profile for transmitting H.225.0 messages. It uses the security measures available under IP-SEC and H.235 and its design facilitates its use in engineering networks.

H.235: It is a security protocol for the H.3xx series. It provides authentication and integration for H.323 based systems, it enables the identification of an individual and not the application. H.235 messages are encrypted in the same way as those in ASN.1. H.235 provides point-to-point and multipoint conferencing for all terminals where H.245 is used as a control protocol.

H.323(SET): It elaborates on the standards for Simple Endpoint Types (SET). SET devices are meant for a single purpose only, they constitute a large number of H.323 capable end systems. These devices enable audio calls with other H.323 endpoints while using only a small portion of the H.323 specifications. SETs need not necessarily be PC-based, they can be relatively inexpensive applications such as the telephone.

H.245: It describes the line transmission of non-telephone signals. The features described include the sending and receiving properties and the desired modes at the receiving end as well as Control and Indication. H.245 messages can be divided into request, response, command, and indication messages. The message sets include Terminal capability messages, Logical channel signaling messages, Request Mode messages, Round Trip Delay messages, etc.

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September 6, 2005 in Standards | Permalink