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H.323. Video Development Initiative. Jill Gemmill University of Alabama at Birmingham Doug Pearson Indiana University, Bloomington Tyler Johnson University of North Carolina, Chapel Hill. Internet2 Commons. Desktop & Room Systems. USB or Appliance Affordable User Friendly.

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h 323

H.323

Video Development Initiative

Jill Gemmill

University of Alabama at Birmingham

Doug Pearson

Indiana University, Bloomington

Tyler Johnson

University of North Carolina, Chapel Hill

NLANR Techs Workshop January 2002

internet2 commons
Internet2 Commons

NLANR Techs Workshop January 2002

desktop room systems
Desktop & Room Systems
  • USB or Appliance
  • Affordable
  • User Friendly

NLANR Techs Workshop January 2002

what is h 323
What is H.323 ?
  • An ITU-T standard for bi-directional exchange of voice, video, and data
  • Applies to an IP network
  • H.323 is a set of standards for group communication
  • TCP Call setup & control
  • UDP for audio/video

NLANR Techs Workshop January 2002

h 323 audio standards
H.323 Audio Standards
  • G711 Audio Codec Required
  • Optional Codecs: G721, G723, G728, G729
  • Bottom Line – Good Audio Requires 64Kb

NLANR Techs Workshop January 2002

h 323 video standards
H.323 Video Standards
  • Video is optional; H.261 required
  • H.261 Picture Size
    • QCIF (176x44 pixels) is required
    • CIF (352x288 pixels) optional
  • H.261 Compressed Data Rate
    • 64kbs – 1.9 kbs
  • H.263 SQCIF, 4CIF, up to 16CIF (1408x1152 pixels)

NLANR Techs Workshop January 2002

slide7

Point-to-Point

Dial by IP address ! or alias

user

user

user

user

Gatekeeper

user

user

MCU

Multipoint

Register with Gatekeeper

Connect through MCU

Point-to-Point & Multipoint

NLANR Techs Workshop January 2002

what is vide net
What is ViDe.Net?
  • An international virtual network providing video teleconferencing, telephone and collaboration services over advanced networks. Architecture used in I2 Commons
  • A voluntary collaboration and open forum
  • A mesh of interconnected 75+ H.323 zones
  • Zone: a collection of users administered by the site.
  • RESULT: individual campuses and network providers interconnect, creating a seamless global environment for teleconferencing and collaboration.

NLANR Techs Workshop January 2002

network requirements
Network Requirements
  • Please use switched Ethernet
  • Category 5 wiring is part of the above
  • 10Mb/sec should be adequate for end points
  • Much higher bandwidth at MCU (multiple 100Mb/sec cards in some systems)

NLANR Techs Workshop January 2002

duplex mismatch the silent performance killer
Duplex Mismatch: the“Silent Performance Killer”
  • A connection set for auto-negotiation, failing to see auto-negotiation at the other end, sets itself to the default – half-duplex.
  • Auto-negotiation doesn’t always work, even when both sides are set to auto
  • Auto-negotiation occurs repeatedly at intervals; what’s right the first time can be wrong later

NLANR Techs Workshop January 2002

detecting duplex mismatch
Detecting Duplex Mismatch
  • Show switch port stats; if mismatched:
    • High CRC or Alignment errors at full duplex end
    • Late collisions at half duplex end
  • UAB sets all user ports to 10/half by default

NLANR Techs Workshop January 2002

firewalls
Firewalls
  • H.323 uses these IP ports:
    • Statically-assigned TCP ports 1718 – 1720 and 1731 for call setup and control.
    • Dynamically-assigned UDP ports in the range of 1024 – 65535 for video and audio data streams.
  • Firewalls don’t allow unrestricted ports: typical modern firewalls and H.323 don’t get along so well.

NLANR Techs Workshop January 2002

slide13

Firewalls – Solutions for H.323

  • [bad; non-scaleable] Allow unrestricted ports for specific, known, external IP-addresses.
  • [better, but still not so good] Use feature of some videoconferencing clients to confine dynamic ports to a specific, narrow range.
  • [OK, but extra admin work and cost] Use an H.323 application proxy.
  • [best] Use a firewall that snoops on the H.323 call set-up channels (static ports) and opens ports for the audio/video (dynamic ports) as needed.

NLANR Techs Workshop January 2002

network issues
Network Issues
  • Ongoing, undiagnosed problems with H.323
    • Jerky video over uncongested networks; why?
    • Quality of H.320 vs. H.323 over uncongested networks
    • >.1% packet loss = unacceptable audio (ITU)
    • >.5% renders session unusable

NLANR Techs Workshop January 2002

h 323 network requirements latency
H.323 Network Requirements: Latency
  • One-Way Delay:
    • [ 0 – 150 ms] : Excellent !
    • [150 – 300 ms] : OK
    • [300 – 400 ms] : Bad
    • [400+ ms] : “Fuggedahboudit”

NLANR Techs Workshop January 2002

h 323 network requirements jitter
H.323 Network Requirements: Jitter
  • Definition: Variation in latency over time.
  • For switched end-points, the primary source of jitter is variation in the store-and-forward time, resulting from network load.
  • H.323 is very intolerant of jitter; clients reduce resolution
  • Rule of thumb?

NLANR Techs Workshop January 2002

h 323 network requirements packet loss
H.323 Network Requirements: Packet Loss
  • Typically due to router or link congestion
    • >0.1% packet loss (ITU) = unacceptable audio
    • >0.5% renders session unusable

NLANR Techs Workshop January 2002

tools for diagnosing h 323 problems
Tools for Diagnosing H.323 Problems
  • Ping
  • TraceRoute
  • PingPlot
  • MRTG
  • Iperf
  • GnuPlotPing
  • Sniffer
  • ViDeNet Scout
  • QCheck
  • OARNet H.323 “Beacon”

NLANR Techs Workshop January 2002

tools vide net scout
Tools: ViDe.Net Scout
  • Scout is a web-based distributed network performance analysis tool developed at the University of North Carolina at Chapel Hill.
  • Scout makes use of the NetIQ Chariot performance testing engine
  • http://scout.video.unc.edu/

NLANR Techs Workshop January 2002

slide20

SURFNet (Netherlands)

CUDI (Mexico)

THROUGHPUT

PACKET LOSS

JITTER

Scouting Advanced Networks10 minute384kbs simulated conference

NLANR Techs Workshop January 2002

slide21

Scouting Out ProblemsPublic Health Outreach Project

THROUGHPUT

  • Remote Health Clinic connected to Internet2 via xDSL
  • Original diagnosis was h.323 problem
  • ISP refused problem ownership until presented with Scout results

NLANR Techs Workshop January 2002

PACKET LOSS

slide22

Iperf – Example on Intercampus DS3http://dast.nlanr.net/Projects/Iperf/

MRTG utilization graph showed bandwidth peaking at capacity ~ 10:00am – 2:00pm

As utilization peaked on the DS3, jitter measured by Iperf rose to unacceptable level

Iperf also reported periodic high packet loss, with no apparent correlation to the low-resolution MRTG utilization reports

slide23

The End-to-End Problem

  • Problem: Poor video and/or audio in a conference between campuses
  • Need: Timely, useful assistance
  • If there’s a firewall, it could take weeks!

NLANR Techs Workshop January 2002

suggested solutions
Suggested Solutions
  • Articulate the E-2-E problem to network management and engineers
  • Bring all engineers together in a place and time to share information.
  • Establish and use reliable communication tools
  • Improve diagnostic tools
  • Have good network documentation for all networks

NLANR Techs Workshop January 2002

future vide net direction middleware for video
Future ViDe.Net Direction: Middleware for Video
  • Directories : key enabler of video teleconferencing.
  • Directories : management tool for tracking and supporting users
  • Directory : a portal for account requests, support, user information updates, etc.
  • Goal: Directory lookup, authenticated click & dial

NLANR Techs Workshop January 2002

middleware for video nsf national middleware initiative
Middleware for Video: NSF National Middleware Initiative
  • NMI Release 1 due this Spring
  • h323Identify and h323Zone object classes will enable h.323 attributes to be added to campus LDAP directories
  • Coordination with Internet2 Middleware activities will create a globally searchable directory of video users
  • Will allow automatic user account management by integration with enterprise directories

NLANR Techs Workshop January 2002

what is vide www vide net
What is ViDe? (www.vide.net)

NLANR Techs Workshop January 2002

sura vide digital video workshop april 23 25 2002
SURA/ViDe Digital Video Workshop April 23-25, 2002
  • 4th Annual Workshop
  • Birmingham, Alabama UAB Campus
  • Digital Video Applications: collaborative conferencing, streaming video, and storing/serving video-on-demand
  • Technical Training & Discussion
  • Program/Technical/Vendor Advisory Committee – please volunteer.

NLANR Techs Workshop January 2002