Routing and wavelength assignment methods in single-hop all-optical networks with blocking

Abstract

W e consider single-hop all-optical networks an which wavelength-routed connections (lightpaths) between source-destination pairs are dynamically established and torn down in response to a random pattern of arriving connection requests and connection holding times. A connection request may be blocked if n o wavelength is available on a suitable path f-rom source t o destination. FOT these networks we consider several methods for routing and wavelength assignment which combine an various ways three main principles: wavelength reservation, protectang threshold and alternate routes. The methods are evaluated and compared in two case studies. In this type of networks the traffic over lightpaths consisting of multiple links is susceptible to high blocking probabilities, which can interfere with the quality of service requirements. It is shown that some of the routing and wavelength assignment methods studied have the potential t o overcome this dijgiculty.

Dynamic lightpath establishment in wavelength routed WDM networks

“…Alternate-path routing relies on a set of predetermined fixed routes between a source node and a destination node [6,7,8,9]. When a connection request arrives, a single route is chosen from the set of predetermined routes, and a lightpath is established on this route.…”

“…In general, first-fit will outperform random wavelength assignment when full knowledge of the network state is available [7]. However, if the wavelength selection is done in a distributed manner, with only limited or outdated information, then random wavelength assignment may outperform first-fit assignment.…”

Performance of WDM transport networks

“…Meanwhile, wavelength interchanging networks admit more long paths which utilize more network resources. This results in higher blocking probability for short paths compared to those in WS networks [37], [50], [62].…”

Traffic grooming and wavelength conversion in optical networks

“…Hence, it is important that a call request is provided service in a fair manner commensurate with the capacity it requests. This capacity fairness is different from the fairness measure based on hop count that has traditionally been addressed in the literature [51] [23].…”

“…Birman and Kershenbaum [51] proposed two techniques for fairness improvement with re spect to hop length. In the first method called Reservation technique, they reserve wavelengths exclusively for longer-hop paths on every link.…”