H.323 is the ITU standard for conferencing which covers Voice, Video and data
conferencing. The applications that conforms to H.323 are VoIP(Voice over IP), White
boarding(or Data conferencing), and Video conferencing. This paper describes the
evolution of the videoconferencing, and the usage of conferencing and how it is becoming
one of the desktop multimedia applications that is being deployed rapidly. The rapid
deployment of desktop conferencing has an impact on the network infrastructure. This
paper provides introduction to the technology and H.323 recommendation which
standardizes the desktop videoconferencing, Cisco’s positioning on this emerging
technology, and how Cisco products can help deploy H.323 applications.
Corporations have been using room-based video conferencing solutions since 1980’s.
These first generation video conferencing solutions were based H.320, an ITU standard
which defines circuit-switched (ISDN) connection based video conferencing.
In the late
80’s, second generation video conferencing solutions, the first desktop based video
conferencing units started emerging.
However, these systems still dependent on H.320
and an ISDN connection to the desktop.
The very high cost of these units, combined with
the difficulties and cost of getting an ISDN connection in those days kept the number of
systems deployed to a small number.
In the mid 90’s, third generation video
conferencing solutions based on local area networks (LAN) based desktop systems started
These solutions were based on proprietary technology and did not
interoperate between different vendor’s solutions.
these solutions required a
very predictable small workgroup LAN to deliver business quality video conferencing.
These reasons and the still relatively high cost of desktop video conferencing solutions
made it difficult, if not prohibitive, for corporations to adopt desktop video conferencing.
A major breakthrough happened when Personal Conferencing Work Group (PCWG)
driven by Intel merged with the conferencing special interest groups of ITU, mainly led
by PictureTel, to create a new standards for video conferencing.
Two standards of
importance are H.323 and H.324.
The H.323 specification, approved by ITU in June,
1996 defines LAN based video conferencing standard and enables interoperability
between different vendors implementations.
The H.324 standard defines plain old
telephone system (POTS) based video conferencing.
Successful mass deployment and adoption of networked multimedia will require
communications infrastructures (most notably computer and telephone networks) to
support end-to-end standards-based networked multimedia technologies as seamlessly as
possible. Standards-based video conferencing is generally governed by the International
Telecommunications Union (ITU) “H-series” recommendations which include: H.320
(ISDN protocol), H.323 (LAN protocol), and H.324 (POTs protocol). These standards
specify the manner in which real-time audio, video, and data communications takes place
over various communications topologies. Standards compliance promotes common