Performance of a robust WDM network with token based reservations and a limited number of lasers at a station

Abstract

The perfomnce of a symmetric Robust WDM network that uses token-passing on the signaling channel and has a limited number of lasers per station is modeled and analyzed for circuit-switched connections. Robust WDM networks use a reservation interval during which all stations cease their WDM transmissions so that the station holding the token may establish a connection with its intended destination. The network performance is analyzed for different network parameters. Simulation results are used to evaluate the accuracy of the model.In recent years, wavelength division multiplexing (WDM) has emerged as the most promising solution to satisfy the increasing need for larger bandwidth [9]. WDM exploits the enormous capacity of the single mode fiber by dividing the available wavelength into smaller, more manageable, multiple wavelengths to carry out more than one transmissions at a time; thereby offering a potential aggregate throughput in Terabits per second range. It has intrigued a large number of researchers in the industry and academia resulting in prototypes such as Rainbow4 & II [lo], STARNET [4], and LIGHTNING [5].WDM architectures are based on transmitters and receivers that can be precisely tuned to predetermined, fixed wavelengths. wavelength of a laser shifts with temperature and the output power of the laser can also change even though a constant input current is applied. Wavelength and power stabilization of laser transmitters is a very critical and expensive task. For this reason the commercial exploitation of WDM systems has not made great progress. This is especially true for short-haul (SH) local area network (LAN) environment where the cost of the fiber and its installation would be considerably less in comparison to the cost of suitable transmitter sources.Robust WDM network, a network being implemented at Colorado State University and University of Colorado, is an approach that allows relaxed manufacturing and operating wavelength tolerances [ 11. Robust WDM networks can be implemented based on several different medium access protocols [7]. This paper evaluates a reservation type, token based medium access protocol for a Robust WDM network with circuit-switched connections.In [23, we modeled and analyzed a symmetric Robust WDM circuit-switched network where each station can access all the c channels of the network. In this paper, we investigate a more realistic case where each station has only a limited number of lasers (c,) and hence can access only c, channels that are randomly spread over the total network channels (c).Section 2 provides a description of Robust WDM network and the token based MAC protocol, Section 3 details the performance model, Section 4 discusses the test results and its comparison with the simulation results, and Section 5 concludes the paper.