Patent ID: 8094655
Filing Date: 2012-01-10
Classification: H04L

Abstract:
1. A communication system for carrying out communications with other communication devices by using a prescribed control protocol on a network, at least one of the communication devices comprising: a digital computer programmed to execute plural programming units comprising: a first tentative address determination unit configured to determine a first tentative address which is a candidate for one of addresses managed by the prescribed control protocol; a packet transmission unit configured to transmit an address initialization packet containing the first tentative address to the network, in order to check presence/absence of another communication device which is using an address identical to the first tentative address; a confirmation packet transmission unit configured to transmit an address confirmation packet containing the first tentative address to the network when not receiving, from another communication device within a first prescribed period of time since transmitting the address initialization packet, any of a response packet indicating that an address identical to the first tentative address is currently used, an address initialization packet containing the first tentative address and an address confirmation packet indicating that the first tentative address is determined as an address of the another communication device; and an address determination unit configured to determine the first tentative address as an address of the communication device, when not receiving, within a second prescribed period of time since transmitting the address initialization packet, any of a response packet indicating that an address identical to the first tentative address is currently used, an address initialization packet containing the first tentative address and an address confirmation packet indicating that the first tentative address is determined as an address of the another communication device, wherein, when receiving, from another communication device within the first prescribed period of time since transmitting the address initialization packet, any of a response packet indicating that an address identical to the first tentative address is currently used, an address initialization packet containing the first tentative address or an address confirmation packet indicating that the first tentative address is determined as an address of the another communication device, the confirmation packet transmission unit transmits an address confirmation packet containing a second tentative address which is different from the first tentative address to the network, and the use of the first tentative address is prohibited for a period of time no shorter than the first prescribed period of time.