Survivable routing and wavelength assignment (RWA) in optical virtual private networks (O-VPNs)

This paper tackles the resource allocation problem for wavelength division multiplexing (WDM) networks supporting virtual private networks (O-VPNs), in which working and spare capacity are allocated in the networks for satisfying a series of traffic matrices corresponding to a group of O-VPNs. Based on the (M:N)ⁿ protection architecture where multiple protection groups (PGs) are supported in a single network domain, we propose two novel integer linear programming (ILP) models, namely ILP-I and ILP-II, aiming to initiate a graceful compromise between the capacity efficiency and computation complexity without losing the ability of addressing the QoS requirements in each O-VPN. ILP-I optimizes the task of resource allocation by taking each O-VPN as a PG, while the ILP-II breaks down each O-VPN into multiple small PGs where all the working paths in each PG are mutually link-disjointedly routed. Experiment results show that in terms of capacity efficiency, a significant improvement can be achieved by ILP-I compared to that by ILP-II at the expense of much longer computation time. Although ILP-II is outperformed by ILP-I, it can handle the situation with an arbitrary size of O-VPNs. We conclude that the proposed ILP-II model yields a scalable solution for the capacity planning in the survivable optical networks supporting O-VPNs based on the (M:N)ⁿ protection architecture.