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Network Characteristics of Video Streaming Traffic

Network Characteristics of Video Streaming Traffic. Ashwin Rao † , Yeon-sup Lim * , Chadi Barakat † , Arnaud Legout † , Don Towsley * , and Walid Dabbous †. * University of Massachusetts  Amherst, USA. † INRIA Sophia Antipolis France. Video Streaming Services. Containers.

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Network Characteristics of Video Streaming Traffic

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  1. Network Characteristics of Video Streaming Traffic Ashwin Rao†, Yeon-sup Lim*, Chadi Barakat†, Arnaud Legout†, Don Towsley*, and Walid Dabbous† *University of Massachusetts  Amherst, USA †INRIA Sophia Antipolis France

  2. Video Streaming Services Containers What are the Network Characteristics of Video Streaming Traffic?

  3. Objective • What exactly happens during video streaming? • Arrival of data packets • Strategies to stream videos • Potential Impact

  4. Outline • Introduction and Motivation • Datasets and Measurement Techniques • Streaming Strategies • Impact of Streaming Strategies

  5. Datasets • YouTube videos • Flash, HTML5, and HD (Flash) • Mobile • Netflix videos - Silverlight • Desktop • Mobile

  6. Measurement Technique Packet Capture 802.11

  7. Measurement Locations • France • Academic (Wired; Wi-fi for mobile) • Residential (Wi-fi) • USA • Academic (Wired; Wi-fi for mobile) • Residential (Wired) YouTube Similar Traffic Characteristics at Each Location YouTube and Netflix

  8. Outline • Introduction and Motivation • Datasets and Measurement Techniques • Streaming Strategies • Impact of Streaming Strategies

  9. Generic Behavior of Video Streaming Steady State Off On Average rate ∝ Video encoding rate Block Size Download Amount Buffering Time

  10. We Identified Three Streaming Strategies No On Off Cycles Streaming strategies vastly different Short On Off Cycles Long On Off Cycles OFF OFF

  11. Streaming Strategies Used Streaming strategy differs with application type and container

  12. Features Controlling Arrival of Data Packets • Buffering Amount • Block Size • Accumulation Ratio Average download rate in steady state phase = Video encoding rate

  13. Arrival of Packets for Short ON OFF Strategy 1.25 64 kB Buffering independent of encoding rate 40 sec. of playback Significant differences between implementations Browser throttles rate Server side rate control with absence of ACK clocks 256 kB

  14. Outline • Introduction and Motivation • Datasets and Measurement Techniques • Streaming Strategies • Impact of Streaming Strategies

  15. Impact of Streaming Strategies Strategy Metric

  16. Model for Aggregate Rate of Streaming Traffic • Objective • Capture statistical properties of aggregate streaming traffic Barakat et al., A flow-based model for Internet backbone traffic, In IMW’02. • Uses • Dimension the network • Quantify impact of user interruptions

  17. Aggregate Rate of Video Streaming Traffic Aggregate Rate Amount of data downloaded Arrival Rate of streaming sessions (Poisson)

  18. Insights from Model • No User Interruptions • Aggregate rate (mean, variance, etc.) independent of streaming strategy • Dimensioning rules do not change • Strategy to optimize other goals (server load, etc.) • Users Interruptions • Impact of buffering amount and accumulation ratio on wasted bandwidth

  19. Summary • Most popular clients and containers for video streaming • Streaming strategy differs with client applications and container • HTML5 streaming vastly differs with client applications • Model to study impact of streaming strategies

  20. Open Questions for the CCN community • Should CCN nodes be aware of the underlying streaming strategy? • What is the optimal streaming strategy for CCN? • Is there an optimal caching strategy for a given streaming strategy? • What is the impact of user interruptions due to lack of interest on CCN caches?

  21. Network Characteristics of Video Streaming Traffic THANK YOU ashwin.rao@inria.fr

  22. BACKUPS

  23. Short or Long • Block Size – Threshold 2.5 MB Long Short Long OFF

  24. ACK Clocks • Source sends packets on receiving ACK • ACKs as an indication of available bandwidth 46 packets sent in the first RTT after an OFF period of more than 500 ms

  25. Conclusion • Most popular clients and containers for video streaming • Streaming strategy differs with client applications and container • HTML5 streaming vastly differs with client applications • Model to study impact of streaming strategies

  26. User Interruptions Video download will be in progress when Playback time downloaded in buffering phase Video duration > 1 - Accumulation ratio Fraction of video watched X

  27. Impact of Losses • Merging of cycles • Playback can freeze • Longer buffering phase

  28. HTML5 • Primary - webM • Very few - h.264

  29. Netflix Streaming Strategies

  30. YouTube Streaming Strategies

  31. Tradeoff • Migration from one strategy to another can have a non-negligible impact Raw File Transfer vs Periodic Buffering vs No ack-clock

  32. Video Streaming in the Internet • 20 % to 40 % of all Internet traffic • Traffic share steadily increasing in recent years • Streaming over HTTP – using TCP • Firewall configurations • TCP flows assumed to be fair

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