In wavelength-routed optical networks, end-to-end connection demands are dynamically routed according to the current network status. NaÃ¯ve path selection schemes, the wavelength continuity constraint and the limited or inaccurate information available can cause the virtual topology resulting from the currently allocated lightpaths to become sub-optimal. We propose an efficient re-optimization technique based on a GRASP meta-heuristic. Our work is focused on a hybrid online-offline scenario: connections are ordinarily routed dynamically using one of the available algorithms for online routing, but occasionally, when reorganization of the current virtual topology is desirable, existing paths are re-routed in order to improve load balancing and hence the ability to efficiently accept further connections. Because global changes of the logical topology and/or routing scheme can be disruptive for the provided connection services, we used iterative stepwise approaches based on a sequence of small actions (i.e., single connection re-routing and on local search from a given configuration). Simulation results demonstrate that several network performance metrics - including connection blocking ratios and bandwidth gains - are significantly improved by such approach. In particular, we achieved to accept more connection requests in our re-optimized networks with respect to the same networks without re-optimization, thus lowering the blocking ratio. Besides, in all tests we measured a notable gain in the number of freed bandwidth OC-units thanks to our re-optimization approach.
|Titolo:||A GRASP-based network re-optimization strategy for improving RWA in multi-constrained optical transport infrastructures|
|Data di pubblicazione:||2010|
|Appare nelle tipologie:||1.1 Articolo in rivista|