All-Optical Monitoring Path Computation Based on Lower Bounds of Required Number of Paths

To reduce the cost of fault management in the all-optical networks, it is investigated to detect the degradation of optical signal quality solely at the terminal points of all-optical monitoring paths. The monitoring paths must be routed so that all single-link failures can be localized using routes information of monitoring paths where signal quality degradation is detected. However, routes computation for the monitoring paths that satisfy the above condition is time consuming. This paper proposes a procedure for deriving the lower bounds of the required number of monitoring paths to localize all the single-link failures, and an efficient monitoring path computation method based on the derived lower bounds. The proposed method repeats the route computation for the monitoring paths until feasible routes can be found, while the assumed number of monitoring paths increases starting from the lower bounds. With the proposed method, the minimum number of monitoring paths with the overall shortest routes can quickly be obtained when the possible terminal nodes of monitoring paths are arbitrarily given. Thus, the proposed method can minimize the operational cost of monitoring the degradation of signal quality and can reduce the overhead traffic transferred through the monitoring paths.