ForestCast: a central solution to heuristically constructing trees

Ghodsi, Ali and Haridi, Seif (2007) ForestCast: a central solution to heuristically constructing trees. [SICS Report]



We present Forestcast which is a flexible and centralized solution to building a forest of trees, which are used to stream live media. A number of heuristic strategies are described to handle joins. Leaves are handled through rejoins. To enable fail-overs, we describe a scheme where the server gives each peer a backup parent such that it is guaranteed that the failure of any peer can be handled. We also describe how the scheme can be efficiently coupled with multiple stripes to allow for better bandwidth utilization. Finally, it is shown how the centralized solution can be decentralized. The provided scheme has three main advantages. i) It is difficult for peers to hack ForestCast as all decisions are taken by the central server. A peer just follows the server's orders about where it should download its stream. It is also possible to use a PKI scheme, where a peer can verify whether it should give its stream to another peer. ii) As the server has complete information about the state of all trees, it can optimize the number and shape of trees based on any metric, e.g. total latency, bandwidth utilization, robustness against failures etc. iii) The client software, running on the peers, contains little intelligence. Hence, it will be simple and can therefore be adapted for various OS and environments. Furthermore, most updates will be to the server infrastructure. A decentralized solution would need software updates to be applied to all peers.

Item Type:SICS Report
Uncontrolled Keywords:Streaming Media, Overlay Networks, Multicast
ID Code:2713
Deposited By:Vicki Carleson
Deposited On:27 Feb 2008
Last Modified:18 Nov 2009 16:13

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