1 / 21

CoopNet: Cooperative Networking

CoopNet: Cooperative Networking. Phil Chou, Venkat Padmanabhan, Helen Wang September 17, 2002. Motivation. “Flash crowd” can overwhelm server often due to news event of widespread interest… … but not always (e.g., Webcast of birthday party)

Samuel
Télécharger la présentation

CoopNet: Cooperative Networking

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CoopNet: Cooperative Networking Phil Chou, Venkat Padmanabhan, Helen Wang September 17, 2002

  2. Motivation • “Flash crowd” can overwhelm server • often due to news event of widespread interest… • … but not always (e.g., Webcast of birthday party) • can affect relatively obscure sites (e.g., election.dos.state.fl.us, firestone.com, nbaa.org) • affects Web content as well as streaming content (live and on-demand) • infrastructure-based CDNs aren’t for everyone • Goal: solve the flash crowd problem!

  3. Cooperative Networking CoopNet Client-server Pure peer-to-peer • CoopNet complements client-server system • Client-server operation in normal times • P2P content distribution invoked on demand to alleviate server overload • Clients participate only while interested in the content • Server still plays a critical role

  4. Research Activities • Web flash crowd alleviation (with Kay Sripanidkulchai) • evaluation using Sep 11 traces from MSNBC • prototype implementation done • paper @ IPTPS ’02 • MDC-based streaming media distribution • evaluation using Sep 11 traces from MSNBC, Akamai, Digital Island • implementation in progress • paper @ NOSSDAV ’02 • patent process in progress • initial discussions with Digital Media Division

  5. Research Activities (contd.) • PeerMetric (with Karthik Lakshminarayanan) • characterize broadband network performance • P2P as well as client-server performance • working with Xbox Online (Mark VanAntwerp) • deployment on ~25 distributed nodes underway • eventual deployment on ~300 Xbox Live beta users • Future directions • CoopNet in a Wireless Mesh Network • good synergy: saves Internet bandwidth, improves robustness

  6. Robustness of Live Streaming • Peers are not dedicated servers  potential disruption due to: • node departures and failures • higher priority traffic • Traditional ALM is not sufficient

  7. Traditional Application-level Multicast

  8. CoopNet Approach to Robustness • Multiple description coding (MDC) • Multiple, diverse distribution trees

  9. Multiple Description Coding Layered coding MDC • Unlike layered coding, there isn’t an ordering of the descriptions • Every subset of descriptions must be decodable • Modest penalty relative to layered coding

  10. Multiple Description Coding • Simple MDC: • every Mth frame forms a description • More sophisticated MDC combines: • layered coding • Reed-Solomon coding • priority encoded transmission • optimized bit allocation

  11. Multiple Distribution Trees

  12. Tree Management • Goals: • short and wide trees • efficiency • diversity • quick join and leave processing • scalability • CoopNet approach: centralized protocol anchored at the server

  13. Centralized Tree Management • Basic protocol • nodes inform server of their arrival/departure • server tracks node capacity and tells new nodes where to join • each node monitors its packet loss rate and takes action when the loss rate becomes too high • simple, should scale to 1000+ joins/leaves per sec. • Optimizations • delay coordinates to estimate node proximity (à la GeoPing) • achieving efficiency and diversity • migrate “stable” nodes to a higher level in the tree

  14. Achieving Efficiency and Diversity NY SEA S Supernode SF

  15. MDC versus SDC Based on MSNBC traces from Sep 11

  16. CoopNet Transport Architecture Embedded Stream ZSF GOF Parse Packetize Optimize (M, p(m)) RD Curve Break Points M descriptions RS Encoder Server Internet Depacketize Embedded Stream(truncated) Reformat Decode Render GOF(quality depends on # descriptions received) m≤ M descriptions RS Decoder Client

  17. Summary • Robustness is the key challenge • MDC with multiple distribution trees improves robustness in peer-to-peer media streaming • Centralized tree management is efficient and can scales

  18. Current Activity • CoopNet media streaming system is being built • Evaluation: • adaptability • server scalability • media stream quality • overhead in MDC and control protocol • Dealing with client heterogeneity • combine MDC with layering

  19. Issues • Firewall and NAT traversal • Digital Right Management issues • ISP pricing policies • Enterprise scenarios

  20. Quality During Multiple Failures

  21. Quality During Single Failure

More Related