Survivable Virtual Topology Reconfiguration Problem on WDM Networks with Reconfiguration Constraint

Abstract

In a \emph{Wavelength Division Multiplexing} (WDM) network, the performance of the virtual topology designed for a pre-specified traffic pattern can be improved by performing {\it virtual topology reconfiguration}. Simultaneously, the provision of survivability of WDM networks is important, because the transmission of huge data should be protected when a fiber fails. Thus, the combination of survivability and reconfiguration is an important issue in WDM networks. In this paper, the {\it Virtual Topology Reconfiguration Problem\/} ({\it VTRP\/}) on WDM networks with a reconfiguration constraint is studied. Given the physical topology, dedicated path-protection virtual topology and a new traffic demand matrix, the goal of VTRP is to reconfigure current virtual topology under the pre-specified reconfiguration constraint ($r$, a positive integer) so that the objective value can be minimized. The objective cost of VTRP is the {\it average weighted propagation delay\/} ({\it AWPD\/}). Because designing a polynomial time algorithm to find the optimal solution of VTRP is impractical when the reconfiguration constraint $r$ is larger, two heuristic algorithms are proposed to solve this problem. They are {\it Positive Reconfiguration Heuristic Algorithm\/} ({\it PRHA\/}) and {\it Conservative Reconfiguration Heuristic Algorithm\/} ({\it CRHA\/}). Experimental results of these algorithms are also given.