Wavelength assignment algorithms for wavelength routed interconnection of LANs

This paper addresses the wavelength assignment issues in interconnecting optical local area networks (LANs) in which a wavelength cannot be reused for local connections. Multiple LANs are connected using a wavelength routing bridge that may or may not support wavelength conversion. Static and dynamic approaches to partitioning of wavelengths for local and global traffic are compared using analysis and simulations. Under the static scenario, the wavelength set is partitioned into fixed sets of local wavelengths and global wavelengths. Dynamic wavelength assignment allows all traffic to use all the wavelengths and thus provides greater statistical multiplexing at the expense of increased implementation complexity. It is found that static wavelength assignment, the easiest algorithm to implement, is significantly outperformed by dynamic algorithms. Several dynamic assignment algorithms are developed, and architectural issues in interconnecting optical networks are discussed. The dependence of the call blocking performance on system parameters, such as the focal and global traffic statistics, and the number of available wavelengths is examined in detail. An elegant outcome is development of a simple, yet accurate, model to predict approximate blocking performance with an arbitrary number of LANs.