Wavelength path reallocation method and upper layer path reallocation method

A wavelength path reallocation method in a path reallocation apparatus for reallocating a wavelength path set in a communication network, comprising:

• a wavelength path designing step in which circuitry of the path reallocation apparatus designs a reallocation destination wavelength path by performing calculation such that a number of use frequency regions in the communication network becomes smaller than a corresponding value before reallocation;
• and
• a wavelength path setting step in which the circuitry changes a reallocation target wavelength path to the reallocation destination wavelength path by using a free wavelength,
• the wavelength path reallocation method further comprising:
• an upper layer path designing step in which the circuitry designs a reallocation destination upper layer path by performing calculation such that the number of wavelengths, a number of communication apparatuses or a communication apparatus cost that is used in the communication network becomes smaller than a corresponding value before reallocation;
• an upper layer path setting step in which the circuitry changes a reallocation target upper layer path to a reallocation destination upper layer path;
• and
• a wavelength path deleting step in which, when there is a wavelength path that does not accommodate any upper layer path, the circuitry deletes the wavelength path.

An upper layer path reallocation method in a path reallocation apparatus for reallocating an upper layer path in a wavelength path set in a communication network, comprising:

• an upper layer path designing step in which circuitry of the path reallocation apparatus designs a reallocation destination upper layer path by performing calculation such that a number of wavelengths, a number of communication apparatuses or a communication apparatus cost that is used in the communication network becomes smaller than a corresponding value before reallocation;
• and
• an upper layer path setting step in which the circuitry changes a reallocation target upper layer path to a reallocation destination upper layer path,
• the upper layer path designing step comprising:
• performing calculation within a range of a constraint that a delay difference or route difference between the reallocation target upper layer path and the reallocation destination upper layer path does not exceed a predetermined threshold.

A path reallocation apparatus for reallocating a wavelength path set in a communication network, comprising:

• circuitry configured to
• design a reallocation destination wavelength path by performing calculation such that a number of use frequency regions in the communication network becomes smaller than a corresponding value before reallocation;
• and
• change a reallocation target wavelength path to the reallocation destination wavelength path by using a free wavelength,
• the circuitry being further configured to:
• perform calculation within a range of a constraint that a delay difference or route difference between the reallocation target wavelength path and the reallocation destination wavelength path does not exceed a predetermined threshold, or a constraint that a route does not change between the reallocation target wavelength path and the reallocation destination wavelength path.