COMMUNICATION DEVICE

摘要

In a procedure of cancelling a location registration in accordance with the Mobile IPv6, when a mobile communication terminal (MN) cannot receive a response to a request for cancelling the location registration, both a location-management apparatus (HA) and a communication apparatus (CN) that is a communication correspondent of the mobile communication terminal have completed processes of cancelling the location registration, but the mobile communication terminal (MN) has not completed processes of cancelling the location registration. As a consequence, the communications cannot be continued. A MN 25 transmits a BU (seq N) 151 to a HA 23. The HA 23 is characterized by being controlled so that the HA 23 will transmit a BA to the MN 25 whenever the HA 23 receives the BU 151. In this case, the HA 23 is designed to transmit a BA 161 to the MN 25 irrespective of whether the HA 23 has completed processes 158 of cancelling the location registration when the HA 23 receives a BU 157 that the MN 25 has transmitted to request the cancellation of the location registration. Accordingly, upon receipt of the BA, the MN 25 deletes the Binding Update List, and thus can complete the processes of cancelling the location registration. Subsequently, the MN transmits a new message representing the completion of the processes of cancelling the location registration in response to the BA transmitted from the HA/CN as a response for cancelling the location registration. When the HA/CN receives, from the MN, the message representing the completion of the processes of cancelling the location registration, the HA/CN executes the processes of cancelling the location registration. When the MN detects an abnormal state where the HA/CN has completed the processes of cancelling the location registration but the MN has not, the MN completes the processes of cancelling the location registration.