Abstract
Evaluation of availability and unavailability of optical connections is necessary for WDM optical networks to make efficient use of optical resources. The design of a protection scheme that improves the availability of high priority optical connections is a major challenge faced by optical network operators. This paper deals with the general protection scheme in WDM optical networks and it provides the mathematical formulation to evaluate the availability/unavailability of protected optical connections. General link failure scenarios are taken into account considering that a link failure affects all the optical connections routed on that link. We have performed some numerical tests and their results are presented to investigate the availability and unavailability degrees for different number of protections.