Multicommodity Flow and Circuit Switching

  • Authors:
  • Tom Leighton;Satish Rao;Aravind Srinivasan

  • Affiliations:
  • -;-;-

  • Venue:
  • HICSS '98 Proceedings of the Thirty-First Annual Hawaii International Conference on System Sciences-Volume 7 - Volume 7
  • Year:
  • 1998

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Abstract

Given a set of request pairs in a network, the problem of routing virtual circuits with low congestion is to connect each pair by a path so that few paths use the same link in the network. We build on an earlier multicommodity flow based approach of Leighton and Rao to show that ``short'' flow-paths lead to path-selections with ``low'' congestion. This shows that such good path-selections exist for constant-degree expanders with ``strong'' expansion, generalizing a result of Broder, Frieze and Upfal. We also show, for infinitely many n, n-vertex undirected graphs along with a set T of connection requests, such that: (a) T is fractionally realizable using flow-paths that impose a (fractional) congestion of at most 1; but (b) any rounding of such a flow to the given set of flow-paths, leads to a congestion of Omega(log n /loglog n). This is progress on a long-standing open problem.