Patent ID: 7136928
Filing Date: 2006-11-14
Classification: H04L,H04W

Abstract:
1. A communication device for carrying out communications according to a prescribed control protocol on a network of a prescribed network layer protocol, comprising: an interface unit configured to make connections to the network of the prescribed network layer protocol; a control protocol processing unit configured to carry out processing regarding data of the prescribed protocol that are transmitted/received through the network of the prescribed network layer protocol; a memory unit configured to store address correspondence information that contains in correspondence a network layer address to be used by each communication device on the network of the prescribed network layer protocol and a prescribed address to be used by each communication device in the prescribed control protocol, for the communication device and other communication devices that are connected to the network of the prescribed network layer protocol; a transmission/reception unit configured to carry out transmission/reception of packets of the prescribed network layer protocol, in which packets of the prescribed control protocol are encapsulated; a determination unit configured to set a prescribed bit sequence value of the network layer address or a datalink layer address of the communication device as a candidate for the prescribed address, transmit an inquiry packet for inquiring whether the prescribed bit sequence value is identical to the prescribed address used by each one of the other communication devices or not, to each one of the other communication devices connected to the network of the prescribed network layer protocol, and determine the prescribed bit sequence value as the proscribed address of the communication device when the prescribed bit sequence value is judged as not identical to any of prescribed addresses used by the other communication devices; and a reply unit configured to receive the inquiry packet that requests a prescribed reply regarding the prescribed address currently used by the communication device from another communication device connected to the network of the prescribed network layer protocol, and return a reply packet for the inquiry packet after waiting for a standby time determined by a method according to the prescribed address currently used by the communication device in a case of replying to the inquiry packet, wherein when the prescribed bit sequence value is judged as identical to one of the prescribed addresses used by the other communication devices, the determination unit transmits the inquiry packet for inquiring the prescribed address used by each one of the other communication devices, to each one of the other communication devices connected to the network of the prescribed network layer protocol, receives reply packets containing the prescribed addresses of the other communication devices that are returned from the other communication devices while waiting for a prescribed waiting time, and determines the prescribed address of the communication device according to the prescribed addresses of the other communication devices contained in the reply packets, wherein the determination unit determines one prescribed address selected according to a prescribed selection method from all or a part of prescribed addresses existing in the prescribed control protocol except for those prescribed addresses contained in the reply packets, as a prescribed address candidate for the communication device, wherein the determination unit carries out a procedure of transmitting a packet for inquiring whether the prescribed address candidate is identical to the prescribed address used by each one of the other communication devices or not to each one of the other communication devices connected to the network of the prescribed network layer protocol and thereafter waiting for a return of a replay packet indicating that the prescribed address identical to the prescribed address candidate is used from one of the other communication devices during the prescribed waiting time, for once or for a prescribed number of times, and determines the prescribed address candidate as the prescribed address of the communication device when the reply packet indicating that the prescribed address identical to the prescribed address candidate is used is not returned from any of the other communication devices while carrying out the procedure for once or for the prescribed number of times, and wherein when the reply packet indicating that the prescribed address identical to the prescribed address candidate is used is returned from one of the other communication devices while carrying out the procedure for once or for the prescribed number of times, the determination unit selects another prescribed address from all or a part of prescribed addresses existing in the prescribed control protocol except for those prescribed addresses contained in the reply packets and a previous prescribed address candidate, as the prescribed address candidate for the communication device, and transmits again the packet for inquiring whether the prescribed address candidate is identical to the prescribed address used by each one of the other communication devices or not to each one of the other communication devices connected to the network of the prescribed network layer protocol.