A quality-of-service (QoS) aware scheme, called precautionary performance monitoring, is proposed to solve the optical impairments and congestion control in coherent optical orthogonal frequency division multiplexed (CO-OFDM) networks. The centralized path computation element (PCE) extensions based on the QoS level are applied to optical performance monitoring in this letter.

A contention resolution scheme, P-cycle auto-switching (PCAS), is proposed in wavelength-switched optical networks (WSONs) based on generalized multi-protocol label switching (GMPLS) to solve backward blocking. This system permits the preferable request and switches the other to a backup path generated by the P-cycle. Simulation results show that the PCAS scheme is effective in mitigating backward blocking, especially under concentrated load.

Current generalized multi-protocol label switching (GMPLS) standards do not include adequate models for wavelength-switched optical networks (WSON) in recovery mechanisms. In this letter, GMPLS/path computation element (PCE) extensions are applied for the restoration of the lightpaths disrupted by collision or optical impairment. A reserved de°ection routing scheme is proposed to achieve fast restoration. It uses the expanded PCE component to compute and assign the backup paths for lightpath recovery. Numerical results demonstrate that this scheme is effective and low cost.