Date Added: May 2010
In this paper, the authors present a simple approach towards providing quality of service based partial protection in optical networks. They use a diversity based protection mechanism to ensure that in the event of link/node failures, a fraction of demand is always survived. To determine routing of optical paths while honoring restrictions such as wavelength continuity and exclusivity restriction, switching capability of OXCs, etc., they present a mixed-integer linear program formulation. Due to large size of the formulation, they develop an accompanied solution approach based on Lagrangian relaxation and sub-gradient optimization.