NSYNC: Network Synchronization for Peer-to-Peer Streaming Overlay
  Construction
Shudong Jin, CWRU


In peer-to-peer streaming applications such as IP television
and live shows, a key problem is how to construct an overlay network
to provide high-quality, almost real-time media relay in an
efficient and scalable manner. Much work has focused on the
construction of tree and graph network topology, often based on the
inference of  network characteristics (such as peer-to-peer delay
and bandwidth). For example, overlay networks are built (and
reconstructed) to leverage multi-parent media relay to reduce the
impact of adversary network conditions in several systems.  Less
attention has been paid to improving the timeliness of media
delivery, and to exploiting the flexibility of applications to
construct better overlay networks.
                                                                              
We describe an ongoing work, NSYNC, on constructing
locality-aware overlay networks for real-time peer-to-peer
streaming. It aims at solving the following problems.  In many
applications, peers must buffer a portion of a real-time event,
e.g., for at least a few seconds. Thus, it introduces both (1)
delay, especially long delay for peers who are many hops away from
the source, and (2) partial ordering between a pair of peers.  With
NSYNC, the applications (such as media players) can slightly
increase or decrease the rate of playing (displaying) media. Thus,
the peers in a network can be synchronized to achieve two
effects. First, late peers can catch early peers (and the source)
such that the entire peer networks improve real-time-ness. Second,
the client/server roles between a pair of neighboring peers can be
reversed, allowing opportunities for constructing more efficient
overlay networks. We are currently analyzing NSYNC and are planning
a simulation study.