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ISP-friendly Peer-assisted On-demand Streaming of Long Duration Content in BBC iPlayer

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In search of scalable solutions, CDNs are exploring
P2P support. However, the benefits of peer assistance can be limited by various obstacle factors such as ISP friendliness—requiring peers to be within the same ISP, bitrate stratification—the need to match peers with others needing similar bitrate, and partial participation—some peers choosing not to redistribute content.
This work relates potential gains from peer assistance to the average number of users in a swarm, its capacity, and empirically studies the effects of these obstacle factors at scale, using a monthlong trace of over 2 million users in London accessing BBC shows online. Results indicate that even when P2P swarms are localised within ISPs, up to 88% of traffic can be saved. Surprisingly, bitrate stratification results in 2 large sub-swarms and does
not significantly affect savings. However, partial participation, and the need for a minimum swarm size do affect gains. We investigate improvements to gain from increasing content availability through two well-studied techniques: content bundling–combining multiple items to increase availability, and historical caching of previously watched items. Bundling proves ineffective as increased server traffic from larger bundles outweighs benefits
of availability, but simple caching can considerably boost traffic gains from peer assistance.

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ISP-friendly Peer-assisted On-demand Streaming of Long Duration Content in BBC iPlayer

  1. 1. ISP-friendly Peer-assisted On-demand Streaming of Long Duration Content in BBC iPlayer Dmytro Karamshuk1, Nishanth Sastry1, Jigna Chandaria2, Andy Secker2 1King's College London, 2BBC R&D CD-GAIN: EPSRC project in collaboration with BBC R&D, http://bit.ly/cd-gain
  2. 2. This talk is about BBC iPlayer
  3. 3. iPlayer is popular and growing Total monthly BBC iPlayer requests across all platforms, since 2009 Introduced in 2005 for 5K users, now covers 50% of the UK population “iPlayer Usage Effect - A Bandwidth Explosion” http://community.plus.net/blog/2008/02/08/iplayer-usage-effect-a-bandwidth-explosion/
  4. 4. Content Delivery: traditional approach Install more distributed caches Requires investments Any alternatives?
  5. 5. Peer-assisted Content Delivery Content Delivery Network user user user user user user average of 5K users online every sec in the first day after release 5K duplicates every second!!! Ask users for assistance
  6. 6. CDNs are interested in traffic savings Content Delivery Network user user user user user user Traffic gain - volume of traffic downloaded from content delivery nodes - total volume of traffic watched by the userss u T T -1=G
  7. 7. Intuition: bigger P2P swarm yields higher gain CDN user 1 user 2 user 3 P2P is self-scaling Bigger swarms yield higher savings
  8. 8. Analytical Model based on M/M/ Queues ci = ui riAverage number of peers online How much we can offload to peers Traffic gain is an exponential function of swarm’s capacity content popularitycontent duration G c 1 e c - by Little`s law
  9. 9. How peer-assistance works in real life … there is a number of obstacle factors they do not address Huang, Cheng et al. [NOSSDAV’2008] Zhao, Mingchen, et al. [IMC’2013] Balachandran et al. [IMC’2013]
  10. 10. Obstacle N1: ISP Friendliness Content Delivery Network P2P increases egress traffic, impacting bandwidth cost for ISPs, Karagiannis et al. [USENIX’2005] Traffic savings drop from 87% to 13% if swarms are localized within ISP and city, Balachandran et al. [IMC’2013]
  11. 11. Obstacle N1: ISP Friendliness Content Delivery Network ISP1 ISP2 P2P increase egress traffic, impacting bandwidth cost for ISPs, Karagiannis et al. [USENIX’2005] Traffic savings drop to 13% if swarms are localized within ISP and city, Balachandran et al. [IMC’2013]
  12. 12. Obstacle N2: Bitrate Stratification Content Delivery Network ISP1 ISP2 1080p 720p 480p
  13. 13. Obstacle N2: Bitrate Stratification Content Delivery Network ISP2 ISP1 -768Kbps ISP1 -1.5Mbps 1080p 720p 480p
  14. 14. Obstacle N3: Partial Participation Content Delivery Network ISP2 ISP1 -768Kbps ISP1 -1.5Mbps Obstacle factors decrease size of swarms Only 31% signed up for sharing in Akamai NetSession Zhao, Mingchen, et al. [IMC’2013]
  15. 15. Users - 2.2 M IP address – 1.3 M Sessions - 15.9 M London, Sep. 2013 Understanding Obstacles with Data-driven Analysis
  16. 16. Dealing with ISP Friendliness Five biggest ISPs account for over 80% of traffic
  17. 17. Two main bitrate formats dominate in over 70% of sessions 1080p 720p 480p Dealing with Bitrates AverageBroadbandSpeed
  18. 18. Results of the Simulations 1080p 720p 480p G c 1 e c An episode of Bad Education series, 100K views
  19. 19. Results of the Simulations potential traffic gains for popular content are high despite obstacles G c 1 e c An episode of Bad Education series, 100K views
  20. 20. How about Unpopular Content? BECAUSE swarms are small  availability is less An episode of What You Can Eat show, 1K views G c 1 e c
  21. 21. Increasing Availability #1: Content Bundling Content Bundling is not effective
  22. 22. Increasing Availability #2: Client Caching Simple caching can boost savings by 23%
  23. 23. Savings across Content Corpus Top-5% of the content corpus accounts for 80% of traffic Most of accesses happen in the first day after release Yes, it’s all about very popular content
  24. 24. Savings across Content Corpus https://vimeo.com/99054874
  25. 25. Conclusions • with peer-assisted delivery savings grow with the demand and size of the content despite obstacles • we give a closed form solution for traffic gains • up to 88% of traffic can be saved • content bundling does not work but caching can boost savings by 23% G c 1 e c
  26. 26. Dmytro Karamshuk King's College London follow me on Twitter: @karamshuk Come to our second talk tomorrow: Room: Ballroom C Time: 4/29/2015 8:30 — 4/29/2015 10:00 Geography Devices PricingOperators Measurement study on 50% of the UK’s population

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