Panasonic Corporation

Moe Hamamoto

Takeshi Kokado

Manabu Yamamoto

Ikue Nakano

A low cost communication apparatus enables detection of an apparatus present on a different network in a router multistage network having a plurality of routers. When a communication apparatus cannot detect, on a network thereof, a desired apparatus, the communication apparatus requests a connection support server securing communication paths with all the apparatuses on a home network, to relay an apparatus detection request. The connection support server transfers the request to relay the apparatus detection request, to an arbitrary apparatus belonging to a different network from the network to which the communication apparatus belongs, and the arbitrary apparatus, by proxy, performs an apparatus detection, and transfers information about a detected apparatus to the connection support server. By obtaining the information from the connection support server, the communication apparatus detects the apparatus on the different network.

Connection support server and communication apparatus

The present invention improves the reliability and safety of communication in a communications system wherein communication is relayed. When an on-premise terminalsets relay information, such as NAT information or the setting information of a packet filter, in a gateway, the relay information is set after confirming whether the NAT information for which a setting attempt is being made duplicates the NAT information of another on-premise terminal. The same applies to the case of deleting relay information. If the NAT information is duplicate, then interference with the communication of the other on-premise terminalis prevented by modifying the relay information for which a setting attempt is being made, specifically the port number of the gatewayon a global network

Relay information setting method and device

Provided is a communication terminal capable of establishing a P2P communication path with a communication terminal connected to a different private network. A communication terminal () transmits and receives messages to and from a server () via a router (), thereby examining a relay characteristic of the router (). When the examined relay characteristic of the router () is Port Reuse, the communication terminal () determines address information, which contains at least a port number of the communication terminal (), which port number is to be used for P2P communication with a communication terminal (), to be address information about the router. The communication terminal () exchanges the determined address information about the router () with the communication terminal (). Based on the exchanged address information, the communication terminal () establishes a P2P communication path with a communication terminal ().

Communication terminal, and communication method

The NAT type of a router can be examined by communicating with one server having one IP address, and a P2P communication path is established efficiently using the NAT type obtained by the examination. A terminaltransmits a plurality of port number examination request packets having a plurality of port numbers of a serverset as the destination port. The terminalrefers to a port number examination response packet received from the serverto acquire a plurality of port numbers obtained by address translation by a routerfor the port number examination request packets respectively. The terminaldetermines the NAT type of the routerbased on the acquired translated port numbers. The terminalsandestablish a P2P communication path efficiently using the determined NAT type.

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Osaka, Japan

Moe Hamamoto