A comparison of allocation policies in wavelength routing networks

We consider wavelength routing networks with and without wavelength convert ers, and several wavelength allocation policies. Through numerical and simu lation results we obtain upper and lower bounds on the blocking probabiliti es for two wavelength allocation policies that are most likely to be used i n practice, namely, most-used and first-fit allocation. These bounds are th e blocking probabilities obtained by the random wavelength allocation polic y with either no converters or with converters at all nodes of the network. Furthermore, we demonstrate that using the most-used or first-fit policies gives an improvement on call blocking probabilities that is equivalent to employing converters at a number of nodes in a network with the random allo cation policy. These results have been obtained for a wide range of loads f or both single-path and general mesh topology networks. The main conclusion of our work is that the gains obtained by employing specialized and expens ive hardware (namely, wavelength converters) can be realized cost-effective ly by making more intelligent choices in software (namely, the wavelength a llocation policy).