Multi-layer virtual topology design in optical networks under physical layer impairments and multi-hour traffic demand
In this paper, we consider the virtual topology design (VTD) problem in multi-protocol label switching (MPLS)/wavelength division multiplexing (WDM) networks with an hourly changing traffic pattern, in the presence of physical layer impairments. We propose a multi-layer VTD scheme that satisfies the constraints in both layers with guaranteed bit error rates assuming no wavelength conversion. The proposed scheme involves interaction of the control planes of MPLS and WDM layers and can be applied without the necessity of a unified control plane. When the virtual topology is designed by considering only MPLS layer constraints, some lightpaths in the designed topology cannot be established, and this may result in a large amount of blocked traffic. We show that, by applying interaction between MPLS and WDM layers during topology design, the blocking ratio is reduced by an amount between 53% and 89% in the investigated cases. We also propose different information sharing strategies between the layers and show that, if physical layer information is available to the MPLS layer, a better blocking performance can be achieved and physical layer resource usage can be reduced by an amount up to 21%.