Selfish routing

Sean Donelan sean at
Thu Apr 24 02:52:16 UTC 2003

How do network operators maintain "fairness" in their networks in
the face of selfish behaivor?  Although this article concerns some
of the "smart routing" products, we see the same thing with other
applications (and even malicious applications like worms).

Every 5 years or so we discuss the need for something like a "penalty
box" for ill behaived traffic.  But in the end, that's too hard.  Its
easier to add capacity than to solve the fairness problem.
  Like motorists who cut off other cars as they swerve onto residential
  streets to speed their own trips, an Internet based on what Dr.
  Roughgarden and Dr. Tardos call "selfish routing" might indeed speed up
  the journeys of some data packets. But over all, the two researchers
  found, the result is quite different. Those shortcuts through side
  streets often have the effect of delaying other drivers, or in the
  Internet's case, packets.
  One antidote to selfish routing, the two researchers found, is more
  capacity. Optimum overall system speeds can be restored despite selfish
  routing by either doubling the number of lanes on a highway or doubling
  the bandwidth of a communications link. Particularly in the case of
  roads, however, that is rarely practical or even desirable.

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