PCE-Based Dynamic Restoration in Wavelength Switched Optical Networks

In GMPLS-controlled wavelength switched optical networks (WSONs), the RSVP-TE signaling protocol is utilized to reserve resources during both lightpath provisioning and dynamic restoration. During restoration, a number of reservation instances are contemporarily triggered by the failure. In such dynamic conditions, resource contention is the main blocking source. Several distributed solutions to reduce the impact of resource contention have been proposed that utilize advanced signaling mechanisms extending the RSVP-TE protocol. Conversely, this paper proposes two centralized solutions based on the Path Computation Element (PCE) that is used to coordinate the dynamic restoration of disrupted lightpaths with the specific aim of reducing resource contentions. Simulation results show that the utilization of the PCE during restoration reduces the blocking at the expenses of an increased recovery time with respect to distributed solutions. In addition, if the PCE is utilized together with the aforementioned advanced signaling mechanisms, the blocking can be further reduced.