Internet2 Commons Technology: H.323 Overview
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Internet2 Commons Technology: H.323 Overview Dr Bob Dixon Chief Research Engineer OARNet and Ohio State University Internet2 Commons Site Coordinator Training September 27, 2004 Austin, Texas
description
Internet2 Commons Technology: H.323 Overview. Dr Bob Dixon Chief Research Engineer OARNet and Ohio State University Internet2 Commons Site Coordinator Training September 27, 2004 Austin, Texas. Video Conferencing vs. Video Broadcasting. Video Conferencing Like a telephone call - PowerPoint PPT Presentation
Transcript of Internet2 Commons Technology: H.323 Overview
Internet2 Commons Technology: H.323 Overview
Dr Bob DixonChief Research EngineerOARNetandOhio State University
Internet2 Commons Site Coordinator TrainingSeptember 27, 2004Austin, Texas
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Video Conferencingvs.
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
Webcasting
3Ohio
New YorkMinnesota
Colorado InternetInternet
Internet Unicast Video Broadcasting
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Ohio
New York
Minnesota
Colorado InternetInternet
Internet Multicast Video Broadcasting
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Internet Point-to-Point Videoconferencing
Ohio
New YorkMinnesota
Colorado
Internet
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Ohio
New York
Minnesota
Colorado InternetInternet
MCU
Internet Multipoint Videoconferencing
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Two Types of Video Conferencing Traditional Internet
Use in special room; rare Use anywhere; ubiquitous
Uses ISDN telephone lines Uses Internet
High installation cost Low installation cost
High usage cost No usage cost
Usage at plateau Usage growing rapidly
Scheduled in advance Impromptu
Professional operator Do-it-yourself
Centralized control Decentralized control
H.320 standard H.323 standard
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Requirements
Good Quality DESKTOP Internet Videoconferencing
1. Fast PC. 500 MHz minimum. 2 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. But new products from Polycom, RADVision, Vcon are promising.
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 VSX-7000
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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
Inte
rnet
PC Client
Appliance
GatewayISDN Telephone Lines
Gatekeeper
MultipointControl Unit
Remote H.320 Video Rooms
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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.
7. Multiple MCUs may be cascaded together for larger video conferences. Or used separately for more simultaneous video conferences.
6. Various brands have various capacities and features.
4. Every person’s audio is always heard by all others.
5. Video from the person who talks loudest is seen by all.
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Gateway (GW)
3. May be physically located anywhere on Earth.
1. Joins H.320 ISDN video calls with H.323 Internet video calls.
2. Calls may be initiated from either side.
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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GateKeeperMCU
H.323 Clients
INTERNET
H.323 Videoconferencing
Web Browser
Real Video
H.323
H.320
Gateway
ISDN
POTS line
Telephone
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Useful References
1. Educause Quarterly tutorial article
http://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
