Bounds on the Blocking Performance of Allocation Policies in Wavelength Routing Networks and a Study of the Eeects of Converters

We consider wavelength routing networks with and without wavelength converters, and several wavelength allocation policies. We show through numerical and simulation results that the blocking probabilities obtained through our previous analytical expressions for the random wavelength allocation and the circuit-switched case provide upper and lower bounds on the blocking probabilities for two wavelength allocation policies that are most likely to be used in practice, namely, most-used and rst-t allocation. Furthermore, we demonstrate that using these two policies has an eeect on call blocking probabilities that is equivalent to employing converters at a number of nodes in the network. These results have been obtained for both single-path and general mesh topology networks, and for a wide range of loads. The main conclusion of our work is that the gains obtained by employing specialized and expensive hardware (namely, wavelength converters) can be realized cost-eeectively by making more intelligent choices in software (namely, the wavelength allocation policy).