Patent ID: 7839807
Filing Date: 2010-11-23
Classification: H04L

Abstract:
1. A communication apparatus connected to a local network connected to an external network in which local network one or more routers are connected in series between the communication apparatus in the local network and the external network, the communication apparatus connecting a communication path to another communication apparatus in the local network, the communication apparatus having a relay function to relay a communication message from said another communication apparatus, the communication apparatus comprising: an upper segment determination section for obtaining and storing address range information which indicates an address range within which an address is capable of being set, the address being of another communication apparatus under an upper router which is connected in the local network and connected on an external network side of a router to which the communication apparatus is connected; a terminal communication path holding section for connecting and holding a communication path to another communication apparatus in the local network; and a message relay section for relaying a communication message from said another communication apparatus, wherein when the terminal communication path holding section receives a first request message requesting to establish the communication path from said another communication apparatus, the terminal communication path holding section stores source address information of the received first request message, transmits a response message to the stored source address information, and establishes the communication path to said another communication apparatus, when the terminal communication path holding section does not receive the first request message from said another communication apparatus, the terminal communication path holding section presumes address information of another communication apparatus under the upper router using the address range information stored by the upper segment determination section, transmits a second request message requesting to establish another communication path to the presumed address information, and receives a second response message to establish said another communication path to said another communication apparatus under the upper router and to store address information of said another communication apparatus to which said another communication path has been established, and the message relay section has a relay function to receive a communication message from said another communication apparatus, to take out destination information which is described in the received communication message and designated by said another communication apparatus, to obtain address information corresponding to the destination information from the address information stored by the terminal communication path holding section, and to transmit the received communication message to the obtained address information.