Algorithms for QoS-Based Wavelength Routing

Abstract

Wavelength routing is a term accepted by many researchers to describe two functions: routing and wavelength allocation (RAW). By means of routing functions, the concatenated WDM links between source and destination can be found, while wavelength allocation refers to the allocation of a wavelength (channel) along each of these links. The term wavelength routing is, however, not just an abbreviation: these two problems, as shown in many of the works, are closely related and can be solved simultaneously. Since the mid-nineties, intensive research activities in the area of wavelength routing have taken place, impelled by the commercial availability of wavelength-routed network elements and systems. So far, the following two categories of approaches to wavelength routing have been pursued:

• Pre-computed routing With pre-computed routing, the traffic matrix is known in advance and the network optimisation and design is made with respect to this matrix for both routing and wavelength allocation.

• On-demand routing On-demand routing is characterised by the connection requests that arrive randomly and must be dynamically accommodated along the time axes within a permanently changing network environment.