1. A computer system, comprising: a host computer; a management computer managing a plurality of tenants, 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; 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 flow information from the management computer.