Assessing the economic benefit of introducing multi-granularity switching cross-connects in optical transport networks

In this article we assess the economic gain obtained by introducing multi-granularity switching optical cross-connects (MG-OXCs) in an optical transport network. An MG-OXC is an equipment able to switch wavelengths, to aggregate (disaggregate) wavelengths into (from) groups of wavelengths called wavebands and to switch wavebands. We evaluate the economic gain by comparing the cost of instantiating (i.e., provisioning) a set of Scheduled Lightpath Demands (SLDs) in a network of wavelength-switching optical cross-connects (WXCs) against the cost of instantiating them in a network of MG-OXCs. We formulate the problems of instantiating SLDs in both a network of WXCs and a network of MG-OXCs as two combinatorial optimization problems and compute approximate solutions to these problems using Tabu Search (TS) based algorithms. Finally, we define a method to determine the conditions (traffic distribution, cost of switching matrices and ports, etc.) under which a network of MG-OXCs is more economical than a network of WXCs