| 摘要 |
When a packet to a terminal is received from a terminal, a management communication processing unit transmits by broadcasting or multicasting to a network a destination information query packet for investigating a gateway device to which the terminal is connected, receives from a gateway device a destination information response packet for notifying that the terminal is connected to the gateway device, and updates a terminal information storage table based on the destination information response packet. When the terminal information storage table is erased, the history information exchange unit transmits by broadcasting or multicasting to the network a history information query packet for requesting to re-notify of the terminal that has been notified in the destination information response packet, receives from the gateway device a history information response packet for re-notifying of the terminal, and updates the terminal information storage table based on the history information response packet. |
| 主权项 |
1. A gateway device being connected to an internal network to which are connected one or more internal terminal devices, and being connected to an external network to which are connected a plurality of relay devices to each of which are connected one or more external terminal devices, and
having a connection relation table indicating, in each record, an external terminal device and a relay device to which the external terminal device is connected, the gateway device comprising: processing circuitry to: each time a communication packet whose destination is any one of the external terminal devices is received from the internal network, refer to the connection relation table, and transmit by broadcasting or multicasting to the external network an investigation packet for investigating a relay device to which a destination external terminal device is connected when a record on the destination external terminal device of the communication packet does not exist in the connection relation table, receive from the relay device to which the destination external terminal device is connected a connection notification packet for notifying that the destination external terminal device is connected to the relay device, and update the connection relation table based on the connection notification packet received; when the connection relation table is erased, transmit by broadcasting or multicasting to the external network a re-notification request packet for requesting the relay device that has transmitted the connection notification packet to re-notify of the external terminal device that has been notified in the connection notification packet; and receive from the relay device that has transmitted the connection notification packet a re-notification response packet for re-notifying of the external terminal device that has been notified in the connection notification packet, and restore the connection relation table based on the re-notification response packet received. |
