H.323 Technology

Dr Bob DixonChief Research EngineerOARNetandOhio State University

Internet2 Commons Site Coordinator TrainingMarch 31, 2005Atlanta, Georgia

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

Ohio

New YorkMinnesota

Colorado InternetInternet

Internet Unicast Video Broadcasting

Ohio

New York

Minnesota

Colorado InternetInternet

Internet Multicast Video Broadcasting

Internet Point-to-Point Videoconferencing

Ohio

New YorkMinnesota

Colorado

Internet

Ohio

New York

Minnesota

Colorado InternetInternet

MCU

Internet Multipoint Videoconferencing

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

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.

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

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

H.323 Video Components

Inte

rnet

PC Client

Appliance

GatewayISDN Telephone Lines

Gatekeeper

MultipointControl Unit

Remote H.320 Video Rooms

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.

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.

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.

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.

GateKeeperMCU

H.323 Clients

INTERNET

H.323 Videoconferencing

Web Browser

Real Video

H.323

H.320

Gateway

ISDN

POTS line

Telephone

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