FairOM (Fair Overlay Multicast)

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A new criteria of fairness

In Internet-scale distributed systems, such as the Grid, reliable and efficient data dissemination plays a very important role. While multiple-tree-based multicasting, in which each peer is supposed to contribute its bandwidth exactly once by being an interior node in one tree, has been explored to address the fairness requirement, we argue that a better way to define fairness is to enforce that peers' contributions are proportional to their total available outgoing bandwidths. This is analogous to taxation or donation. In taxation or donation, it is desirable for people to give the same percentage of their available capital as contribution to the society (here, we assume all the people are in the same tax bracket).

FairOM's primary advantage is:

Performance-wise, enforcing proportional contribution provides an environment to support multiple simultaneous multicasting sessions that may not otherwise be achieved by simply asking every peer to contribute arbitrarily. Consider the following example in which peers A and B are both going to multicast a movie and each multicast will span all the peers in the network. Suppose that A builds its multicast forest first and one peer, C, is assigned to contribute 90% of its outgoing bandwidth to it. Then when B tries to establish its multicast forest, chances are that C just does not have enough bandwidth to support it because it has contributed too much to the first multicast session. In this case, the construction of forest for B becomes either infeasible or, barely feasible by using up all of C's outgoing bandwidth and making C a hot-spot/bottleneck. In this case, if we instead let each peer contribute roughly the same percentage of its outgoing bandwidth, say 20%, then C has a chance to support the two simultaneous multicasting sessions.



Faculty: Hong Jiang

Student: Yijun Lu


We are currently developing a prototype on Planet-Lab.