On the Effect of Large-Scale Deployment of Parallel Downloading

  • Authors:
  • Christos Gkantsidis;Mostafa Ammar;Ellen Zegura

  • Affiliations:
  • -;-;-

  • Venue:
  • WIAPP '03 Proceedings of the The Third IEEE Workshop on Internet Applications
  • Year:
  • 2003

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Abstract

In the presence of multiple mirror servers that can servethe same information, clients can improve their performancewhen downloading large files by conncurrently retrievingdifferent parts of the file from different servers. Inprevious work, experiments with a single client have shownthe potential for parallel downloading schemes to improvethe performance perceived by this single client. In this paperwe consider the question of what happens when paralleldownloading is widely adopted within the Internet. Tothat end we start with an experimental evaluation of variousparallel downloading schemes and their performance fromthe perspective of a single client. We use these results as abenchmark for a set of simulations in which we investigatethe performance of parallel downloading when performedby multiple clients. We find that, because parallel downloadingincurs additional overhead as a result of its use ofmore network connections, large-scale use of this techniquecan actually lead to overall degradation of the performanceexperienced by clients. Further, we uncover a "fairness"tradeoff in that any performance improvement experiencedby clients performing parallel downloading comes at the expenseof clients who simply go to a single server to retrievefiles.