1. A computer system, comprising: a host computer distributed in separated sub-networks; a management computer managing a plurality of tenants based on tenant management information and address management information, the plurality of tenants configured to be isolated from each other by a backbone network; wherein at least one of the plurality of tenants comprises at least one of one or more virtual resources and one or more physical resources on the host computer, wherein the at least one of the one or more virtual resources and the one or more physical resources are identified by the address management information, the management computer creating flow information comprising tenant information relating to information of the at least one of the one or more virtual resources and the one or more physical resources identified by the address information and action information to identify a flow of a frame for each of the plurality of tenants; and one or more switches controlling an access of each of the plurality of tenants by using address information of the at least one of the one or more virtual resources and the one or more physical resources based on the flow information from the management computer, wherein the one or more switches are configured to forward frames having an address resolution protocol (ARP) broadcast to the management computer.