BiToS: Enhancing BitTorrent for
         Supporting Streaming
                  Applications


             Aggelos Vlavia...
Motivation
   Apply time sensitive function into BitTorrent(BT), which can
    distribution of time insensitive content.
...
Motivation
   BASS: BitTorrent Assisted Streaming System for Video-on-
    Demand
       Client will not download any da...
Remaining Windows

    BiToS Approach       Small Windows


       a




Storing buffer
                                 ...
BiToS Approach
   Probability p to download a piece in the High Priority
    set (p can be adjust to adapt different cond...
Simulation setting
   4:400 for Seed and Leechers
   Flash crowds at the beginning
   10 minutes length, video quality ...
Simulation result (I)


                        Missing playback deadline
                        Why not decrease further...
Simulation result (II)



                              Use 5 min length video




                 Time for seeder stay i...
Improvement to be made (I)
   Analysis of Probability p is not detail enough
       How to trigger the dynamic
       H...
Improvement to be made (I)
   Dynamics of the seeder/leecher ratio
   Identify the event for triggering dynamic
    adap...
BitTorrent Assisted Streaming System
(BASS)

   BitTorrent assisted the system only
   Media server is the main support ...
BASS Architecture




                    12
Simulation Result (I)




                  BASS reduce media server load
                  131 to 87kBps (slope) ~less th...
Simulation Result (II)
   The average required bandwidth on the
    media server can be decreased by up to 34%
    when u...
Existing BT application for streaming

   Current BT application for streaming:
       FoxTorrent
           Streaming ...
VoD with BT-assist
   Following BT mechanisms might need to be
    re-design/re-construct
   Peer selection
   Piece se...
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Gabriel - Department of Computer Science and Engineering, HKUST

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Gabriel - Department of Computer Science and Engineering, HKUST

  1. 1. BiToS: Enhancing BitTorrent for Supporting Streaming Applications Aggelos Vlavianos, Marios Iliofotou, Michalis Faloutsos (From INFOCOM 2007) 1
  2. 2. Motivation  Apply time sensitive function into BitTorrent(BT), which can distribution of time insensitive content.  Minimize the change of BT mechanism to achieve this  To reduce start-up time  To evaluate the video quality  To view the downloading video first (in highly polluted network)  view-as-you-download service  Rarest first order V.S. playback smooth (playing order)  Tunable between pure streaming and original BT  Three different piece selection mechanisms  Only need to change this part in BT 2
  3. 3. Motivation  BASS: BitTorrent Assisted Streaming System for Video-on- Demand  Client will not download any data prior to the current playback time  Time constrained data  stronger incentive with Tit-for-Tat peers will avoid to be Free-Riders  Use BT to handle live streaming, change the tracker entity and some parts of peer communication protocol (signal handover=new protocol) 3
  4. 4. Remaining Windows BiToS Approach Small Windows  a Storing buffer 4
  5. 5. BiToS Approach  Probability p to download a piece in the High Priority set (p can be adjust to adapt different condition)  Probability (1-p) to download a piece in the Remaining Pieces set  One more function to determine if the piece can be downloaded on time or not  Compare the expected playback time and minimum time  Adaptation of probability p can be triggered by playback deadline missing 5
  6. 6. Simulation setting  4:400 for Seed and Leechers  Flash crowds at the beginning  10 minutes length, video quality 500Kbps  Download/Upload rate 500/500Kbps  Other use BT default settings (256Kb per piece?)  No dynamic adaptation of probability p  No peer dynamic  Only one performance metrics continuity index (CI) from Coolstreaming  Average overall continuity index? 6
  7. 7. Simulation result (I) Missing playback deadline Why not decrease further? Since the flash crowd of peer at beginning of simulation 7
  8. 8. Simulation result (II) Use 5 min length video Time for seeder stay in the network 8
  9. 9. Improvement to be made (I)  Analysis of Probability p is not detail enough  How to trigger the dynamic  How to set the value  Probability can be a function of buffer status or time  No study effect of buffer length  Simple theory to explain why ~8% total file as high priority set is optimal (High CI) 9
  10. 10. Improvement to be made (I)  Dynamics of the seeder/leecher ratio  Identify the event for triggering dynamic adaptation of p  Further simulation and application to real BT system 10
  11. 11. BitTorrent Assisted Streaming System (BASS)  BitTorrent assisted the system only  Media server is the main support (Maybe)  Simply adding two systems together for BASS  From the media server, BASS downloads pieces in- order, and skip pieces are downloading/ downloaded/ expected to finish download before playback deadline  BitTorrent are directly used for streaming application without any modification 11
  12. 12. BASS Architecture 12
  13. 13. Simulation Result (I) BASS reduce media server load 131 to 87kBps (slope) ~less than half 13
  14. 14. Simulation Result (II)  The average required bandwidth on the media server can be decreased by up to 34% when using BASS compared with pure media server case  Average client waiting time is decreased by 27% compared to the pure media server case. 14
  15. 15. Existing BT application for streaming  Current BT application for streaming:  FoxTorrent  Streaming Fast Delivery: Watch video and listen to audio as it downloads.  Open source FoxTorrent, Firefox extension that lets users stream torrents as they download, from their web browser  http://www.foxtorrent.com/  http://groups.google.com/group/foxtorrent/topics?gvc= 2 15
  16. 16. VoD with BT-assist  Following BT mechanisms might need to be re-design/re-construct  Peer selection  Piece selection  Pull based  Push and Pull based 16

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