Algorithms and Stability Analysis for Universal-Swarming-Based Content Distribution

We consider the issues of applying the universal swarming technique to transfer massive content efficiently. In a swarming session, a file is distributed to all the receivers by having all the nodes in the session exchange file chunks. By universal-swarming, not only all the nodes in the session, but also some nodes outside the session may participate in the chunk exchange to speed up the distribution process. We present a universal swarming model where the chunks are distributed along different Steiner trees rooted at the source and covering all the receivers. We assume chunks arrive dynamically at the sources and focus on finding stable universal swarming algorithms. To achieve the maximum throughput, universal swarming usually involves a tree-selection subproblem of finding a min-cost Steiner tree, which is NP-hard. We propose a universal swarming scheme that employs an approximate tree-selection algorithm. We show that it achieves network stability for a reduced throughput region, where the reduction ratio is the same as that of the tree-selection algorithm. We propose a second universal swarming scheme that employs a randomized tree-selection algorithm. It achieves the maximum throughput region, but with a weaker stability result.