NETWORK OPERATION SYSTEM, NETWORK OPERATION METHOD AND NETWORK OPERATION PROGRAM

Data transfer with high throughput is enabled between servers. When in a set of sites each having a usable network operation unit, a new site is added or an existing site withdraws, designing is executed for determining a combination of the network operation units each one of which is to be used in each added or withdrawn site such that at least a site which transmits or receives data becomes reachable based on a connection relationship between each paired network operation units added or withdrawn, and when a combination of the network operation units is determined in the designing, the network operation unit determined is considered as a network operation unit to be newly used in each site.