Communication system, IPsec tunnel termination device, and IPsec tunnel communication continuation method used for them

摘要

A control unit 15 of a connection destination device 1 assigns a connection destination device address to a virtual line unit 13. In response to an instruction from the control unit 15, the virtual line unit 13 sets a line (A) 11 as an active line to be used for communication and, to make it appear to an external device that the connection destination device address is assigned to the line (A) 11, notifies a preceding-stage device 2 that the line (A) 11 has the connection destination device address. Thereafter, the line (A) 11 is used to establish, communicate, or disconnect an IPsec tunnel from a connection source device 3 to the connection destination device 1.