Efficient routing and wavelength assignment for reconfigurable WDM ring networks with wavelength converters

  • Authors:

  • Li-Wei Chen;Eytan Modiano

  • Affiliations:

  • Laboratory for Information and Decision Systems, Massachusetts Institute of Technology, Cambridge, MA;Laboratory for Information and Decision Systems, Massachusetts Institute of Technology, Cambridge, MA

  • Venue:
  • IEEE/ACM Transactions on Networking (TON)
  • Year:
  • 2005

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Abstract

We consider the problem of wavelength assignment in reconfigurable WDM networks with wavelength converters. We show that for N-node P-port bidirectional rings, a minimum number of ⌈PN/4⌉ wavelengths are required to support all possible connected virtual topologies in a rearrangeably nonblocking fashion, and provide an algorithm that meets this bound using no more than ⌈PN/2⌉ wavelength converters. This improves over the tight lower bound of ⌈PN/3⌉ wavelengths required for such rings given in [1] if no wavelength conversion is available. We extend this to the general P-port case where each node i may have a different number of ports, Pi and show that no more than ⌈Σi Pi/4⌉ + 1 wavelengths are required. We then provide a second algorithm that uses more wavelengths yet requires significantly fewer converters. We also develop a method that allows the wavelength converters to be arbitrarily located at any node in the ring. This gives significant flexibility in the design of the networks. For example, all ⌈PN/2⌉ converters can be collocated at a single hub node, or distributed evenly among the N nodes with min {⌈P/2⌉ + 1, P} converters at each node.