Node Apparatus, Data Relay Method and Computer-Readable Recording Medium

1. A node apparatus comprising: a receiving unit which receives a data frame from one of a plurality of adjacent node apparatuses with which links exist; a storing unit which stores an identification information management table in which frame identification information with which the data frame may be uniquely identified, and overlapped data identification information with which, when data frames having the same frame identification information are received in an overlapped manner, the data frame received first among the overlapped data frames may be uniquely identified, are associated; a processor which performs a process including: first judging whether or not a final destination of the received data frame is the node apparatus itself; second judging, when the final destination of the received data frame is not the node apparatus itself, whether or not a registration that matches the frame identification information of the received data frame exists in the identification information management table; third judging, when it is determined by the second judging that the registration exists in the identification information management table, whether or not the overlapped data identification information of the received data frame and the overlapped data identification information corresponding to the registration match; and discarding the received data frame when a judgment of a mismatch is made by the third judging; and performing a retransmission of the received data frame to another adjacent node that has not been a transmission destination of the data frame, when a judgment of a match is made by the third judging.

2. The node apparatus according to claim 1 , wherein the node apparatus itself is a relay node apparatus exclusively for relaying; and the overlapped data identification information is apparatus identification information with which the relay node apparatus that the data frame first goes through may be uniquely identified.

3. The node apparatus according to claim 2 , wherein the process further includes registering the frame identification information and the overlapped data identification information of the received data frame, when the second judging makes a judgment that the registration does not exist in the identification information management table.

4. The node apparatus according to claim 3 , wherein the process further includes fourth judging, when the second judging makes a judgment that the registration does not exist in the identification information management table, whether or not setting of the overlapped data identification information of the received data frame has already been made, wherein when the fourth judging makes a judgment that the setting has not been made, the registering sets the apparatus identification information of its node apparatus itself as the overlapped data identification information of the received data frame, and also associates and registers, in the identification information management table, the frame identification information of the received data frame and the apparatus identification information of its node apparatus itself.

5. The node apparatus according to claim 1 , wherein the overlapped data identification information is a combination of apparatus identification information with which the node apparatus that issues the overlapped data frames may be uniquely identified, and a number of retransmissions information that indicates a number of issuances of the overlapped data frames by the node apparatus.

6. The node apparatus according to claim 5 , wherein the process further includes registering the frame identification information and the overlapped data identification information of the received data frame, when the second judging makes a judgment that the registration does not exist in the identification information management table.

7. The node apparatus according to claim 1 , wherein the process further includes: fifth judging, when the final destination of the received data frame is the node apparatus itself, whether or not a registration that matches the frame identification information of the received data frame exists in the identification information management table; and second registering at least the frame identification information of the received data frame in the identification information management table, when a judgment is made by the fifth judging that the registration does not exist in the identification information management table, wherein the discarding discards the received data frame when a judgment is made by the fifth judging that the registration exists in the identification information management table.

8. The node apparatus according to claim 1 , wherein the process further includes sixth judging whether or not, from the adjacent node apparatus that is a transmission destination of a transmitted data frame, a reception notification of a reception of the data frame has been received, wherein the performing a retransmission performs a retransmission of the transmitted data frame to an adjacent node apparatus that has not been the transmission destination, when a judgment is made by the sixth judging that the reception notification has not been received.

9. The node apparatus according to claim 8 , wherein the process further includes generating, at a prescribed timing, retry information including a combination of information indicating a date and a time of the retransmission and apparatus identification information with which the adjacent node apparatus to which the retransmission is performed may be uniquely identified, and the apparatus identification information of the node apparatus itself, and transmitting the generated retry information to an upper-level apparatus.

10. A data relay method comprising: receiving a data frame from one of a plurality of adjacent node apparatuses with which links exist by using a computer; first judging whether or not a final destination of the received data frame is the node apparatus itself by using the computer; second judging, when the final destination of the received data frame is not the node apparatus itself, whether or not a registration that matches a frame identification information of the received data frame exists in an identification information management table in which frame identification information with which the data frame may be uniquely identified, and overlapped data identification information with which, when data frames having the same frame identification information are received in an overlapped manner, the data frame received first among the overlapped data frames may be uniquely identified, are associated by using the computer; third judging, when it is determined by the second judging that the registration exists in the identification information management table, whether or not the overlapped data identification information of the received data frame and the overlapped data identification information corresponding to the registration match by using the computer; discarding the received data frame when the overlapped data identification information of the received data frame and the overlapped data identification information corresponding to the registration do not match by using the computer; and performing a retransmission of the received data frame to another adjacent node that has not been a transmission destination of the data frame, when the overlapped data identification information of the received data frame and the overlapped data identification information corresponding to the registration match by using the computer.

11. A non-transitory computer-readable recording medium having stored therein a program for causing a computer of a node apparatus to execute a process comprising: receiving a data frame from one of a plurality of adjacent node apparatuses with which links exist; first judging whether or not a final destination of the received data frame is the node apparatus itself; second judging, when the final destination of the received data frame is not the node apparatus itself, whether or not a registration that matches a frame identification information of the received data frame exists in an identification information management table in which frame identification information with which the data frame may be uniquely identified, and overlapped data identification information with which, when data frames having the same frame identification information are received in an overlapped manner, the data frame received first among the overlapped data frames may be uniquely identified, are associated; third judging, when it is determined by the second judging that the registration exists in the identification information management table, whether or not the overlapped data identification information of the received data frame and the overlapped data identification information corresponding to the registration match; discarding the received data frame when the overlapped data identification information of the received data frame and the overlapped data identification information corresponding to the registration do not match; and performing a retransmission of the received data frame to another adjacent node that has not been a transmission destination of the data frame, when the overlapped data identification information of the received data frame and the overlapped data identification information corresponding to the registration match.