Domain control method and domain control device

A domain control method performed in a domain control device that assigns an address to be used, among a plurality of administrative domains, on a communication route from a starting point administrative domain at a starting point of communication to an ending point administrative domain at an ending point of communication, each administrative domain being a device group composed of one or more devices including a virtual server and each administrative domain controlled by a control device of a network system, where available addresses are set for each protocol used for communication between an administrative domain and another administrative domain, the method comprising:

• a first step of specifying the one administrative domain and another administrative domain on the communication route by using information concerning protocols used for communication between the one administrative domain and another administrative domain;
• a second step of acquiring, for each protocol of a plurality of protocols, a first set of addresses set in the one administrative domain and a second set of addresses in the another administrative domain specified by the first step;
• and
• a third step of assigning an address usable in common to one administrative domain and another administrative domain among the first and second set of addresses acquired by the second step,
• wherein
• information concerning protocols used for communication between the one administrative domain and another administrative domain is information defining protocol types from among (i) an insertion protocol which is a protocol whose address is inserted in a corresponding domain, (ii) a removal protocol which is a protocol whose address is deleted in a corresponding domain, and (iii) a transfer protocol which is a protocol which is transferred based on an address in the corresponding domain, and
• the first step specifies target domains on the communication route on a basis of a protocol type to be provided by the target domains, and the third step assigns an address that is common to the respective protocol type provided by the specified target domains.