Report from Internet2/SURA P2P conference

by Andy Oram

Related link: http://www.internet2.edu/activities/html/p2pworkshop.html




Last week I visited a surprisingly chilly Phoenix, Arizona to deliver
a

keynote speech

at the workshop

Collaborative Computing in Higher Education: Peer-to-Peer and
Beyond
.
I no longer think that P2P requires its own distinctive research, but
I still find that people trying to meet the needs of P2P
infrastructure and applications are doing some of the most interesting
work in computing. Here are some key points I heard at the
conference. A longer article with more general points will be posted later this week.






  • The value of a peer-to-peer mindset is shown in a modest project
    called

    Your Own Internet Distribution
    ,
    presented by
    Bob Lindell.
    Its goal is to produce an efficient multicast system for networks that
    don't support IP multicast.



    According to Lindell, a typical way someone might add users to a
    multicast would be to build a mesh in which all users are fully
    connected—for instance, ten (4+3+2+1) connections for five users.
    Then the application would perform some sophisticated routing analysis
    and come up with a hierarchical tree that represents the best routes
    between all users. The problem is that the application would have to
    rebuild the mesh and the tree every time a user comes or goes, and
    that creates burdensome overhead in a real-life situation.



    A P2P mindset takes account of transient users and designs a solution
    that is less elegant in theory but more workable in practice. No mesh
    is created, but each user that connects is added to the best point in
    the tree. If one node becomes overwhelmed with traffic, it kicks one
    or more children off the tree and they rejoin it elsewhere.





  • Bill St. Arnaud
    ,
    as well as other presenters, emphasized that there are plenty of
    legitimate applications, especially peer-to-peer applications, that
    require high bandwidth. So bandwidth problems won't go away, even if
    all the file-sharing sites are shut down.



    St. Arnaud, who helps Canadian universities develop fiber networks, is
    in a highly unusual position because his colleagues have plenty of
    bandwidth and are looking for applications to fill it. His

    presentation

    showed some promising educational projects.




  • Most university administrators, in contrast, really need to rein in
    file sharing. It's driving normal research- and class-oriented traffic
    off of their networks. The most promising technologies for "traffic
    shaping" don't involve blocking particular ports (because file sharing
    programs can work around that) or hard limits on usage (because a lot
    of network users have big bandwidth needs for good reasons related to
    university business). Instead, sophisticated traffic shaping watches
    each users' bandwidth use and gradually cuts down on the bandwidth
    allocated to them as usage increases.




  • Two projects illustrate the validity of a peer-to-peer approach in
    ways that are particularly easy to see:







    • Porivo
      ,
      presented by CEO

      Gordon Kass
      ,
      is a commercial venture about which I wrote a

      profile

      last year. Porivo installs its software on participating end-user
      sites to test the responsiveness of web sites under absolutely
      realistic conditions.





    • SHOCK
      ,
      a research project presented by

      Eytan Adar
      ,
      lets people find authorities on particular subjects while maintaining
      the privacy of both the authorities and the requesters. Each expert
      stores a profile on his or her personal computer and the profile is
      queried when anyone sends a request to the network for help.






    In addition,

    Raymond Leung

    described a video distribution system (an application pursued by lots
    of P2P researchers) that depends on storing chunks of videos on
    users's systems, and

    Werner Vogels

    presented a

    publish/subscribe system

    that pushes new articles of interest through a chain of users.