Virtual topology reconfiguration for mixed-line-rate optical WDM networks under dynamic traffic

For the mixed-line-rate (MLR) wavelength-division multiplexing (WDM) networks, each wavelength in a fiber can provide different transmitting rates (in 10/40/100 Gbps) by using different modulation formats. Since the MLR-WDM becomes a cost-efficient technique for the network upgrading, the problem of supporting virtual topology reconfiguration (VTR) becomes an important issue. In this paper, the VTR problem is studied for MLR-WDM networks under dynamic traffic demand. By monitoring traffic of the lightpaths, a reconfiguration method is proposed to follow the changes in traffic without a priori knowledge of the future traffic pattern. The proposed algorithm can optimize resource utilization and network traffic performance by either adjusting (increasing or decreasing), adding or deleting one or more lightpaths at a time. Simulations reveal the effects of the various system parameters. Specifically, we find that the proposed method adapts very well to the changes in the offered traffic on MLR-WDM networks.