A computer system, comprising a plurality of subsystems coupled via a network, each of the plurality of subsystems comprising at least one computer and at least one network device, the at least one computer including a first processor, a first memory coupled to the first processor, and a first network interface for communicating to/from another device, the at least one network device including a second processor, a second memory coupled to the second processor, and a second network interface for communicating to/from another device, the computer system comprising a subsystem control module for managing the plurality of subsystems, characterized by the subsystem control module being configured to: select one or more subsystems as a group management node from among the plurality of subsystems, in a case of receiving a build request for a group which is used for providing a service and which includes at least one subsystem; and command the one or more group management nodes to measure a network quality between the respective group management node and each of the plurality of subsystems other than the respective group management node; each of the one or more group management nodes being configured to: measure, by using an IP packet including a time to live, TTL, the network quality between the respective group management node and each of the plurality of subsystems other than the respective group management node that are included in a predetermined network range, wherein the predetermined network range is a range within a predetermined number of hops in the network from the respective group management node, and wherein the TTL is set to a value small enough so that the IP packet can only arrive at the subsystems other than the respective group management node that are included in the predetermined network range; the subsystem control module being configured to: receive a measurement result of the network quality from each of the one or more group management nodes; determine, based on the measurement result of the network quality received from each of the one or more group management nodes, a configuration of the group which includes at least one subsystem; and transmit to each of the one or more group management nodes a group build command including information on the determined configuration of the group. select one or more subsystems as a group management node from among the plurality of subsystems, in a case of receiving a build request for a group which is used for providing a service and which includes at least one subsystem; and command the one or more group management nodes to measure a network quality between the respective group management node and each of the plurality of subsystems other than the respective group management node; measure, by using an IP packet including a time to live, TTL, the network quality between the respective group management node and each of the plurality of subsystems other than the respective group management node that are included in a predetermined network range, wherein the predetermined network range is a range within a predetermined number of hops in the network from the respective group management node, and wherein the TTL is set to a value small enough so that the IP packet can only arrive at the subsystems other than the respective group management node that are included in the predetermined network range; the subsystem control module being configured to: receive a measurement result of the network quality from each of the one or more group management nodes; determine, based on the measurement result of the network quality received from each of the one or more group management nodes, a configuration of the group which includes at least one subsystem; and transmit to each of the one or more group management nodes a group build command including information on the determined configuration of the group. receive a measurement result of the network quality from each of the one or more group management nodes; determine, based on the measurement result of the network quality received from each of the one or more group management nodes, a configuration of the group which includes at least one subsystem; and transmit to each of the one or more group management nodes a group build command including information on the determined configuration of the group.