Dynamic weights for OCSPF route computation in optical networks

Abstract

In current routing algorithms for wavelength switched optical transport networks, based on the Open Constrained Shortest Path First (OCSPF) concept, the effects of traffic dynamicity (the fact that lightpaths (a.k.a. optical connections or optical LSPs) are continuously being set-up and torn down) are not taken into account. Therefore, in this study four new link metrics are proposed, each of which could be used to replace the current metrics being used. Two metrics are based on the average load ρ on a link during a given timeframe. Two other metrics are based on an estimate of the number of setup requests nbr that will be blocked during the lifetime of the lightpath that is being set up. It is shown that the former two link metrics (i.e. those based on ρ) significantly reduce the blocking probability compared to the case in which a constant link metric is used. The latter two metrics (i.e. those based on nbr) however perform only slightly better or even worse than the original algorithm. In addition, it is observed that by taking into account the traffic dynamicity using the average load on a link, the amount of sustainable demand can be increased by about 10% for a given blocking probability.