Waveband Switching: A Scalable and Cost Efficient Technique for Optical Network Design

摘要

Wavelength-routed optical networks using wavelength division multiplexing (WDM) provide the solution to keep up with the ever-increasing bandwidth demands of network users. However, the rapid advances in using dense WDM technology (which employs fibers with hundreds of wavelengths) and world-wide fiber deployment have brought about a tremendous increase in the number of ports at optical cross-connects (OXCs), as well as in the cost, complexity and difficulty associated with control and management of such large-scale OXCs. The OXC is the key traffic switching or routing element in an optical network. Waveband switching (WBS) can reduce this increasing control complexity and number of ports (viz. the prime cost source) associated with ordinary optical cross-connects (OXCs). In this work, we show how an optical network can be designed using WBS and concentrate on the fundamental problem of routing and wavelength assignment (RWA), such that the port count required to satisfy a given set of static demands is minimized. We introduce an integer linear programming (ILP) model and compare two heuristic algorithms: the waveband oblivious routing and wavelength assignment (or WBO-RWA) algorithm, and the waveband aware algorithm balanced path routing with heavy-traffic first waveband assignment (or BPHT) algorithm. Our simulations show that BPHT performs close to the ILP model and considerably better than WBO-RWA. Our results also provide valuable insights into the effect of waveband granularity on the performance of WBS algorithms, as well as the tradeoffs between the wavelength-hop and the port count.