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Network based Videoconferencing Steve Williams

Network based Videoconferencing Steve Williams. Why don’t people use ILT / ICT. Not relevant Not easy to use Not integrated Not reliable Not effective. £5.5million project with £2.1m European funding European open procurement Rollout and procurement group membership Technical

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Network based Videoconferencing Steve Williams

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  1. Network based Videoconferencing Steve Williams

  2. Why don’t people use ILT / ICT • Not relevant • Not easy to use • Not integrated • Not reliable • Not effective

  3. £5.5million project with £2.1m European funding • European open procurement • Rollout and procurement group membership • Technical • Non technical • HE and FE representatives • Focus on • Ease of use • Suitability for use in a teaching environment • Appropriate use of effective technology

  4. 3 x 29” monitors, 2 x cameras + document camera • High quality audio and video • Interactive whiteboard / Large video screen • Dedicated ‘data PC’ for application sharing • We do not use data sharing facilities in VC equipment • Laptop connection • Up to 4Mbps connection speed

  5. The Beginning… You have diverse groups of users on diverse network connected machines wanting to do different things at different times and they all want the network to respond in an appropriate manner. If you do not have an adequately ‘overprovisioned’ network… …the network must be able to differentiate between real-time critical and non-real time services.

  6. Real-Time critical traffic Video Conferencing IP Telephony Video Streaming Web browsing MLE/VLE E-mail

  7. Network Applications WWW E-mail MLE/VLE WWW E-mail MLE/VLE Videoconferencing IP Telephony Streamed Video Videoconferencing IP Telephony Streamed Video

  8. Network Access School Internet Switch Access Router RBC/ISP School

  9. An overprovisioned network is one where the traffic is able to flow freely from any point on the network to any other point without suffering from delays by being queued. If your network has bottlenecks or ‘low’ speed links and you want to run videoconferencing you must consider providing some guarantee of service to certain types of traffic… …or it will not be reliable.

  10. Differentiated Services • Ability to provide Quality of Service based on classes or types of traffic • Expedited forwarding (EF-PHB) • Real-time critical traffic • Low-loss, low jitter, fastest throughput up to limit • E.g. 1Mbps continuous throughput • Videoconferencing and voice traffic • Assured Forwarding (AF-PHB) • ‘Guaranteed’ bandwidth over time x • E.g. 1Mbps averaged over 10 seconds • Video Streaming

  11. Network Metrics for Videoconferencing • Available bandwidth • Enough! – actually enough x 1.5 minimum • Availability • Should never be < 99.95% (22 minutes/month) • SLA should state measured per rolling month max • Packet Loss • <0.25% absolute max • Inter Packet Delay Variation (IPDV or Jitter) • +- 30ms • Round Trip Time (RTT) or One Way Delay(OWD) • <100ms (50ms)

  12. Providing Guaranteed Service • Three normal classes + an option • EF (Voice and Video) • AF (Video Streaming and network updates) • BE (Best Effort – everything else) • LBE (Less than BE – throw away first) EF – 20% of link AF - 15% of link BE - remainder

  13. Think about • The whole network path and the equipment in that path • The type of traffic on each link • The worst link in the chain • Providing Quality of service • Engineering connections

  14. MAN QoS WVN QoS WVN Studio WVN Gatekeeper/proxy WVN Switch MAN Access Router 4 ports H.323 only Firewall Campus core switch/router Remote Campusswitch/router Campus QoS VLAN & queuing WVN Studio WVN Studio Institution Network Topology SWMAN / NWMAN

  15. WVN is hybrid ISDN & IP solution • ISDN = circuit switched • Call setup, dedicated bandwidth • Just like a telephone call • IP = packet switched • Call setup, contended bandwith • More like a very fast postal service

  16. The Welsh Video Network www.wvn.ac.uk s.r.williams@swansea.ac.uk

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