Method for optimizing path of optical network, and optical transmission node for realizing path optimization

An optical transmission node for implementing path optimization which transmits a wavelength multiplexed optical signal, comprising:

• a span information retaining section for retaining, as span information, information about conditions of a transmission path between an optical transmission node of interest and another adjacent node connected thereto;
• a span information cumulative transmission section, which cumulatively transmits, in order, the span information retained in each of a plurality of add-drop nodes from a starting-point node to an end-point node, adds said span information retained in said span information retaining section to the span information received from the another adjacent node and relating to nodes located before said another adjacent node, and transmits said added span information to yet another adjacent node;
• and
• an optimal pathway determination section which determines, in a case where a node of interest is said end-point node, as a pathway optimal for said wavelength path a combination of optical links from said starting-point node to said node of interest satisfying predetermined transmission conditions, on the basis of span information retained by said span information retaining section and cumulative span information transmitted from a plurality of adjacent nodes connected to said node of interest;
• each of said add-drop nodes has an electrical regenerative relay function section selectively subjecting at least one of one or more wavelengths forming said wavelength multiplexed optical signal to electrical regenerative relay;
• and
• when the electrical regenerative relay is determined to be required according to a result of cumulative determination made by said end-point node, said end-point node effectively controls the electrical regenerative relay function section of said add-drop nodes in the pathway determined by said optimal pathway determination section.