H.323 Technology

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H.323 Technology
Dr Bob Dixon Chief Research Engineer OARNet and Oh
io State University Internet2 Commons Site
Coordinator Training March 31, 2005 Atlanta,
Georgia
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Video Conferencing vs. Video Broadcasting
Video Conferencing Like a telephone call Two -
Way Call up or Answer
Video Broadcasting Like watching Television One
- Way Tune In or enter URL Streaming Webcasti
ng
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Internet Unicast Video Broadcasting
Minnesota
New York
Internet
Colorado
Ohio
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Internet Multicast Video Broadcasting
Minnesota
New York
Internet
Colorado
Ohio
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Internet Point-to-Point Videoconferencing
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Internet Multipoint Videoconferencing
Internet
MCU
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Two Types of Video Conferencing
Traditional Internet
Usage at plateau
Usage growing rapidly
H.320 standard H.323
standard
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Requirements
Good Quality DESKTOP Internet Videoconferencing
1. Fast PC. 500 MHz minimum. 1 GHz best. 2.
Good quality video conferencing equipment.
Forget web cameras. Forget software like
Netmeeting. 3. GOOD Internet connection.
Most large university networks are good.
Forget 56K modem dial-in. Cable modems and
DSL are possible.

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Video Conferencing Products
1. Software-based Generally slow and
non-standard not very satisfactory.
Examples Microsoft NetMeeting, White Pine
CUSeeMe.
2. Hardware-based, plug into PC USB Port.
Newest approach will become ubiquitous
Examples Polycom ViaVideo, VCON ViGo.
3. Hardware-based, standalone appliance, no PC
involved. Easiest to use, best
quality. Example Polycom Viewstation
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Typical Equipment
Desktop and Laptop Polycom ViaVideo -
cost 400 Also requires PC Classroom
and conference room Polycom Viewstation -
model VSX-7000 - Cost 5000 Also requires
TV monitor or projector
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H.323 Video Components
PC Client
Appliance
Internet
Multipoint Control Unit
Remote H.320 Video Rooms
ISDN Telephone Lines
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Multipoint Control Unit (MCU)
1. Allows more than two people to be in a video
conference.
2. May be physically located anywhere on Earth.
3. Functions as an Internet server for video
conferencing.
4. Every persons audio is always heard by all
others.
5. Video from the person who talks loudest is
seen by all.
6. Various brands have various capacities and
features.
7. Multiple MCUs may be cascaded together
for larger video conferences. Or used
separately for more simultaneous video
conferences.
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Gateway (GW)
1. Joins H.320 ISDN video calls with H.323
Internet video calls.
2. Calls may be initiated from either side.
3. May be physically located anywhere on Earth.
4. Various brands have various capacities and
features.
5. Multiple gateways may be used for more
simultaneous calls.
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Gatekeeper (GK)
1. Controls all MCUs, gateways, and clients in
its zone. A zone is any collection of
H.323 devices you choose to work closely
together. The devices may be physically
located anywhere on Earth.
2. All H.323 devices must register with a
gatekeeper, before they can do very much.
3. There can be only one active gatekeeper in a
zone.
4. May be physically located anywhere on Earth.
5. May be physically located in an MCU, a
gateway, a router, or a PC. But it is
independent of them.
6. Multiple gatekeepers may be neighbors of
each other, in different zones.
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Gatekeeper (GK) (contined)
7. Provides calling with telephone numbers
and nicknames, instead of IP addresses. A
gatekeeper is analogous to a domain name server,
in this sense.
8. Provides optional control of what each user
can do bandwidth and speed
limits access to gateways and
MCUs
9. Note that calls DO NOT go THROUGH a
Gatekeeper.
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H.323 Videoconferencing
H.320
Telephone
ISDN
POTS line
Gateway
INTERNET
H.323 Clients
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Useful References
1. Educause Quarterly tutorial article
www.educause.edu/pub/eq/eqm00/eqm004.html 2. The
Video Conferencing Cookbook, and other
materials at http//vide.utk.edu 3. The
Megaconference http//www.megaconference.org