Abstract: A network repeater apparatus connected to a plurality of networks is provided which includes a VLAN tag addition section (15) or a VLAN tag rewrite section (17) that performs prescribed VLAN tag processing with respect to a communication packet based on prescribed information of the communication packet when the communication packet is input from any one among a plurality of networks, an address translation section (16) that translates a source address of the communication packet based on the prescribed information, and an input and output section (11) that outputs to a prescribed virtual network a communication packet which has been subjected to at least either one of processing by the VLAN tag addition section (15) or the VLAN tag rewrite section (17) or address translation by the address translation part (16), whereby access can be made to a common device while ensuring security between the networks.

Abstract: Information may be distributed to a plurality of communication devices connected to a network by creating a distribution route including a plurality of levels by assigning a plurality of following level stations (0-level to n-level stations) to the distribution route, distributing information from one of the communication devices as an m-level station in a lower level to one of the communication devices as an (m+1)-level station in a level lower than the lower level in which the m-level station is present using the distribution route, monitoring a distribution status of the information distributed, and changing the distribution route based on the distribution status.

Abstract: In a distributed file system, a file server stores files, and a cache server stores copies of files, server information, and control information. The server information defines a communication procedure used in communication with the file server, and the control information controls a client so that in case of necessity of a file, the client sends a file-acquisition request to the cache server when the cache server is in operation, and to the file server in accordance with the server information when the cache server is not in operation. The cache server sends to the client the control information and the server information in response to a startup notice sent from the client, and sends, in response to a file-acquisition request sent from the client, one of the copies of the files corresponding to the file-acquisition request received, to the client.

Abstract: A network repeater apparatus connected to a plurality of networks is provided which includes a VLAN tag addition section (15) or a VLAN tag rewrite section (17) that performs prescribed VLAN tag processing with respect to a communication packet based on prescribed information of the communication packet when the communication packet is input from any one among a plurality of networks, an address translation section (16) that translates a source address of the communication packet based on the prescribed information, and an input and output section (11) that outputs to a prescribed virtual network a communication packet which has been subjected to at least either one of processing by the VLAN tag addition section (15) or the VLAN tag rewrite section (17) or address translation by the address translation part (16), whereby access can be made to a common device while ensuring security between the networks.