Enhancement of blocking performance in all-optical WDM networks via wavelength reassignment and route deviation

This paper deals with the problem of improving the performance of all-optical Wavelength Division Multiplexing (WDM) networks in terms of blocking probability. Blocking in such network architecture is caused mainly by the so-called wavelength continuity constraint (wcc), which requires a provisioned lightpath to occupy the same wavelength on all the links along its route. To alleviate the effect of wcc on the blocking performance, a rerouting strategy is proposed. The main idea behind this strategy lies in ensuring the creation of wavelength-continuous routes for the connections that are blocked due to wcc. Particularly, the proposed rerouting strategy is built upon two main pillars, namely wavelength reassignment and route deviation. The former strives to keep the physical route followed by the lightpath intact, while the latter changes the route of the lightpath when wavelength reassignment proves to be ineffective. The performance of the rerouting strategy is studied through extensive simulations in the context of networks employing the least congested path (LCP) routing algorithm and the first-fit (FF) wavelength assignment strategy. The reported results show that the proposed rerouting strategy can guarantee significant enhancement in terms of blocking probability while achieving near-optimal performance for networks utilizing a small number of wavelengths per fiber.