COMMUNICATION DEVICE, COMMUNICATION SYSTEM, AND COMMUNICATION METHOD

PROBLEM TO BE SOLVED: To provide a communication device, communication system, and communication method, for performing system changeover without reducing communication quality.SOLUTION: The communication device that constitutes a redundant configuration with another communication device and communicates with a single opposite device, with which the other communication device communicates, using a communication path differing from that used by the other communication device includes: a changeover unit for changing over the communication device between an operation system and a standby system; a first acquisition unit for acquiring first time at which the communication device has been changed over to the operation system; a transmission unit that, when the communication device is the operation system, generates a first notification packet that includes the first time and is used for notifying that the communication device is the operation system, and transmits the first notification packet to the opposite device; a second acquisition unit that receives a second notification packet from the other communication device through the opposite device, and acquires second time at which the other communication device has been changed over to the operation system, from the second notification packet; and a control unit that, when the first time is earlier than the second time, makes the transmission unit stop transmitting the first notification packet. The changeover unit, after the control unit making the transmission unit stop transmitting the first notification packet, changes over the communication device to the standby system.SELECTED DRAWING: Figure 9 【課題】 通信品質を低下させずに系切り替えを行う通信装置、通信システム、及び通信方法を提供する。【解決手段】 通信装置は、他の通信装置とともに冗長構成され、他の通信装置とは別の通信経路を介し共通の対向装置と通信し、自装置を運用系及び予備系の間で切り替える切り替え部と、自装置が運用系に切り替えられたときの第１時刻を取得する第１取得部と、自装置が運用系である場合、第１時刻を含み、自装置が運用系であることを通知する第１通知パケットを生成して、対向装置に送信する送信部と、他の通信装置から対向装置を介して第２通知パケットを受信し、第２通知パケットから、他の通信装置が運用系に切り替えられたときの第２時刻を取得する第２取得部と、第１時刻が第２時刻より早い場合、送信部に第１通知パケットの送信を停止させる制御部とを有し、切り替え部は、制御部が送信部に第１通知パケットの送信を停止させた後、自装置を予備系に切り替える。【選択図】図９