H.323 Desktop Video Conferencing

April 12, 1999

Contact: Teresa Thomas

As part of long-range videoconferencing and network planning, H.323 projects have been defined to examine and define this technology for use within the Virginia Community College System (VCCS). The major goal is to increase the number of videoconferencing sites while enhancing and expanding the capabilities of the VCCS to provide more and improved services to customers.

The existing VCCS Desktop and Commonwealth Conferencing center models are based on a distributed environment, non-Quality of Service (QOS), H.323 video (15 – 30fps) (H.261), audio (G.711) and T.120 Standard based data sharing. It provides a long-term solution in that it implements a standard’s based, scaleable, lower cost technology for desktop driven videoconferencing. Through the adoption of the International Telecommunication Union H.323 Standard, colleges will be able to communicate effectively among themselves and with non-VCCS partners.

Conceptually, there is no "video network" associated with the distributed video model. It is a collection of video codecs installed in desktop computers, and video switches, individually connected to the existing LAN/VCCS infrastructure. The codecs can connect to each other dynamically (point to point mode), just like placing a telephone call. As with a telephone call, the only thing a video codec needs to know to make a connection is the IP address, alias or terminal id which act like a telephone number of the receiving video codec. Multipoint conferencing still requires a video switch, but the ability to perform point to point conferencing without a video switch dramatically reduces the need for video switches. This architecture also allows video codecs and video switches to be added as needed, without disrupting existing H.323 videoconferencing operations. Any Net.Work.Virginia customer may upgrade their desktop computer to include an H.323 codec, 10/100 minimum switched LAN connection to meet the level of technology described in this document.

As might be expected, the effectiveness of desktop videoconferencing will depend heavily on the capabilities of the campus network. Refer to Network Infrastructure documents posted for recommendations.

The client is the Personal Computer containing video codec and conferencing application software connected to a local area network (LAN). TCP/IP is the transport from the client to other clients within the LAN, Intranet or internet.

This component of H.323 manages the bandwidth inbound and outbound from the LAN. Gatekeepers register clients and coordinate communications with other gatekeepers. There are four features within a Gatekeeper:

1. Admission control authorizes clients access to the LAN.
2. Bandwidth control for each network segment managed.
3. Client network addresses are translated so that participants can dial network locations with aliases (such as email addresses) instead of IP address.
4. Call management monitors H.323 calls, tracks rejected calls, accounts for us of WAN links, and monitors other H.323 Components.

Enables H.323 clients to communicate with H.320 systems.

Negotiates multiple clients in a conference format. The client does scheduling from a GUI interface which allows the client to pick a "virtual" conference room, decide if the meeting is private or public, and the host client can then invite other participant to join for scheduled or impromptu virtual meetings right at the client desktop.

Benefits of H.323

• Enables comprehensive flexible applications configuration for voice over IP, desktop video conferencing, collaborative computing and electronic whiteboard applications.
• Sets multimedia standards for existing multivendor IP-based infrastructures. Defines legacy infrastructure interoperability issues, and allows customers to deploy H.323-based applications without replacing desktop or network infrastructure equipment.
• Manages "network loading" by enabling administrators to restrict available bandwidth for conferencing, eliminating the congestion and blockage of other types of traffic simultaneously using the network. Also, administrators may restrict the use of bandwidth allowed into the LAN.
• Endorsed by leading industry vendors and organizations.
• Conferences can include endpoints with various capabilities. For instance, an audio-only client can participate in a conference with clients that support video and/or data. An H.323 compliant multimedia terminal can share the data portion of a videoconference with a T.120 data-only terminal, while sharing, video, audio and data with other H.323 clients.

Using the technology for the desktop video conferencing, it will be possible to provide the following functions and/or services:

• Conduct face to face meetings with one or more participants.
• Conduct face to face meetings with up to eight H.323 desktop client or Netmeeting participants.

• Share documents, spreadsheets, files, and collaborative white boarding ideas.

• Interact with colleagues, inside and outside the VCCS network, without the extra travel and time expenses associated with current meetings.

• Distance learning, counseling, telemedicine, security and more…

The H.323 standard is highly deployable in today’s higher horse-power and more flexible Local Area Network (LAN) bandwidth options. The proof of concept for Quarter Screen Desktop Video Conferencing (DVC) has been successfully validated. Full Sreen DVC is under current evaluation.

For more detailed information on Full and Quarter Screen DVC, review the H.323 Quarter Screen Desktop Videoconferencing and H.323 Full Screen Desktop Videoconferencing project documents.

Submitted by: Pamela Perdue, Advanced Technology Engineer