Scheduled light path switching in optical networks and automatic assessment of traffic impairments that would result from adding or deleting a channel in a wavelength-division multiplexed optical communication network

A traffic scheduler for a wavelength-division multiplexed optical communication network that includes a plurality of nodes and a plurality of links interconnecting the nodes, wherein each link includes at least one link-length optical fiber and at least some of the nodes are access nodes, the scheduler comprising:

• a database storing:
• (a) information about topology of the optical communication network and (b) information indicating:
• (i) which wavelengths are illuminated in ones of the link-length optical fibers, (ii) which wavelengths in ones of the link-length optical fibers are assigned to carry traffic and (iii) for each wavelength/link-length optical fiber combination that is assigned to carry traffic, a start time of an assignment and an end time of the assignment;
• a traffic request receiver configured to receive a first electronic signal indicating:
• (a) a request to transport proposed traffic over the optical communication network between a source access node and a destination access node and (b) an amount of the proposed traffic;
• a duration calculator configured to automatically calculate a calculated assignment duration based on the amount of the proposed traffic;
• a link-length optical fiber search engine configured to automatically search the information in the database for a set of the link-length optical fibers, such that:
• (a) the set of link-length optical fibers extends contiguously between the source access node and the destination access node, (b) at least one wavelength in common among all the link-length optical fibers of the set is illuminated and (c) each combination of the at least one wavelength and a link-length optical fiber of the set is available to carry traffic at some common start time and thereafter for at least the calculated assignment duration;
• a wavelength selector configured to, if the set of link-length optical fibers is found, automatically select a wavelength of the at least one wavelength in common;
• a database updater configured to, if the set of link-length optical fibers is found, alter the information stored in the electronic memory so as to indicate, for each link-length optical fiber of the set, the selected wavelength is assigned to carry traffic beginning at the common start time and thereafter for the calculated assignment duration;
• and
• a success/failure signal sender configured to, if the set of link-length optical fibers is found, send a second electronic signal indicating the set of link-length optical fibers, the selected wavelength and the common start time.