JP2007053588A - Packet retransmission method, packet retransmission system, packet retransmission program, and program recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packet retransmission method capable of preventing delay of packet delivery and increase of network load due to increase of packet transfer quantity, by suppressing retransmission process for the packets that are not required to be retransmitted. <P>SOLUTION: A data receiver 2 succeedingly receives a plurality of transmission packets 1-6 for the amount of window size from a data transmitter 1. If it detects packet missing due to abnormal reception of transmitted packets, the number of transmission packets 1 and 2 that are normally received before occurrence of packet missing as well as the information about normal reception/abnormal reception relating to transmission packets on and after serial number of a transmission packet 3, of which the packet missing occurred are put in one confirmation response which is returned to the data transmitter 1 at packet reception of the amount of window size, or at time out of a timer 201 that waits for predetermined confirmation response return for sending back. Only transmission packets 3 and 5 of serial number with which the data transmitter 1 comes into abnormal reception are retransmitted as retransmission packets 3 103pr, 5 105pr. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a packet retransmission method, a packet retransmission system, a packet retransmission program, and a program recording medium, and in particular, a packet retransmission method, a packet retransmission system, a packet retransmission program, and a program recording capable of preventing an increase in packet delivery delay and network load. It relates to the medium.

Conventionally, in data transmission / reception requiring a short cycle and certainty, a flow control method using a window size that defines the number of packets that can be received simultaneously has been adopted. As a result, as described in Japanese Patent Laid-Open No. 2000-078118 “Automatic retransmission request data transmission method” of Patent Document 1 and Re-specialized WO 01/099355 of Patent Document 2 “Packet retransmission system and packet retransmission method”. The side can continuously transmit multiple packets at a time, and the receiving side sends an acknowledgment indicating how many of the packets that have been continuously transmitted within the window size have been received. By sending back to, efficient and reliable data transmission / reception was possible.
JP 2000-078118 (pages 6-7) Re-specialized WO 01/099355 (pages 25-26)

  However, in such a conventional method, the confirmation response only notifies the transmitting side of information indicating which packet has reached correctly. For this reason, even when one missing packet occurs, the transmitting side needs to retransmit the packet that has normally arrived after the missing packet.

  In addition, when the order of transmitted packets is switched on the network, even if all the packets have arrived normally just by changing the order, the receiving side changed the order as if a packet loss occurred. The sender was requested to resend subsequent packets.

  As a result, retransmission processing is also performed on packets that do not require retransmission, which induces an increase in network load due to an increase in packet delivery delay and packet transfer amount.

  Accordingly, an object of the present invention is to provide a packet retransmission method for solving such problems as an increase in retransmission packet processing load and network load on the data transmission / reception side and occurrence of packet distribution delay.

  In order to solve the above-described problems, the packet retransmission method, the packet retransmission system, the packet retransmission program, and the program recording medium according to the present invention employ the following characteristic configuration.

(1) When the data transmitting side continuously transmits a plurality of packets to the data receiving side via the network using the window control, the data receiving side continuously transmits the packets transmitted via the network. When returning a confirmation response for notifying the data transmission side of whether or not the data has been normally received, if a packet loss is detected due to abnormal reception, a packet loss is included in one confirmation response to be returned. The data is sent back by including the number of normally received packets before the generated packet and information on normal reception / abnormal reception for each of one or more packets after the sequence number of the packet in which the packet loss has occurred. A packet retransmission method in which the transmission side retransmits only the serial number packet that was abnormally received on the data reception side.
(2) When the data receiving side receives a packet with a serial number that is older than the serial number sequence, it immediately receives a subsequent packet without returning an acknowledgment indicating that the packet has been dropped to the data transmitting side. Continue processing, receive the weak packet normally after the old serial number packet received earlier, and replace all the packets to be received. (1) The packet retransmission method according to (1) above, in which, when it is found that the data has been received, a confirmation response indicating that the data has been normally received is returned to the data transmission side.
(3) The timing at which the data receiving side returns the confirmation response to the data transmitting side is the number of packets corresponding to the window size, or in advance after receiving the first packet that has not yet received the confirmation response. The packet retransmission method according to (1) or (2), which is one of cases where a predetermined time has elapsed.
(4) On the data reception side, when there is a transmission packet to be transmitted to the data transmission side, the acknowledgment is carried on the transmission packet to be transmitted to the data transmission side, and the data transmission is performed. The packet retransmission method according to any one of (1) to (3) above.
(5) Based on the confirmation response, the data transmission side grasps the normal reception / abnormal reception of each packet transmitted / received to / from the data reception side via the network according to the time zone, and The packet retransmission method according to any one of (1) to (4), wherein the packet transmission time zone can be adjusted.
(6) In the case where the data transmission unit continuously transmits a plurality of packets to the data reception unit via the network using window control, the data reception unit has continuously transmitted through the network. When returning a confirmation response notifying the data transmission unit whether or not the packet has been normally received, if a packet drop is detected due to abnormal reception, the packet is included in one confirmation response to be returned. By including and returning the number of normally received packets before the packet in which the loss occurred and the information on normal reception / abnormal reception for each of one or more packets after the sequence number of the packet in which the packet loss occurred, A packet retransmission system in which the data transmission unit retransmits only a serial number packet that has been abnormally received by the data reception unit.
(7) When the data receiving unit receives a packet with a serial number that is higher than the sequence number, the data receiving unit immediately returns a confirmation response indicating that the packet is missing to the data transmitting unit. Continue the reception process, and normally receive the weak-numbered packet that has been reversed by the old-numbered serial number packet that was previously received, and the packet to be received by the serial number switching process of the received packet is The packet re-transmission system according to (6), wherein when it is found that all of the data are complete, a confirmation response indicating that the data has been normally received is returned to the data transmission unit.
(8) When the timing at which the data receiving unit returns the confirmation response to the data transmitting unit is the number of packets corresponding to the window size, or after receiving the first packet that has not yet returned the confirmation response The packet retransmission system according to the above (6) or (7), which is one of cases where a predetermined time has elapsed.
(9) In the data receiving unit, when there is a transmission packet to be transmitted to the data transmitting unit, the confirmation response is combined with the transmission packet to be transmitted to the data transmitting unit, and the data transmission is performed. The packet retransmission system according to any one of (6) to (8), wherein the packet retransmission system is returned to the network.
(10) Based on the confirmation response, the data transmission unit grasps normal reception / abnormal reception of each packet transmitted / received to / from the data reception unit via the network according to a time zone, and the data reception side The packet retransmission system according to any one of (6) to (9), wherein the transmission time zone of the packet can be adjusted.
(11) A packet retransmission program for realizing the packet reproduction method according to any one of (1) to (5) as a program executable by a computer.
(12) A program recording medium for recording the packet reproduction program of (11) on a recording medium readable by a computer.

  According to the packet retransmission method, packet retransmission system, packet retransmission program, and program recording medium of the present invention, the following effects can be obtained.

  The first effect is that a plurality of received packets are sent back by including the arrival status of individual packets with serial numbers after the lost packet in one confirmation response, so the transmitting side transmits within the window size. It is possible to identify a packet that did not normally reach the receiving side, and retransmit only a packet that did not reach normally.

  As a result, the number of retransmitted packets can be reduced and the network load can be reduced as compared with the conventional method in which all the packets after the first packet that did not arrive normally need to be retransmitted. Compared to the method of notifying the arrival status of all packets as an acknowledgment, only the arrival status of the serial number after the first packet that did not arrive normally is notified, thereby reducing the amount of information in the acknowledgment and processing. Speeding up can also be achieved. The effect increases as the window size increases and the number of packets that are continuously transmitted and received at a time increases.

  The second effect is that if the packet order is reversed in the network and arrives at the receiving side, it is determined in advance that a packet dropout has occurred without immediately sending back an acknowledgment requesting retransmission to the transmitting side. During this time, the receiving side waits for the reception of the subsequent packet, and when the packet whose order has been changed subsequently arrives normally, the receiving side simply resends it to the transmitting side simply by changing the order of the packets. No need to request.

  As a result, when the packet reception order is reversed, unnecessary retransmission processing can be reduced as compared with the conventional method in which an acknowledgment of a retransmission request is immediately returned to the transmission side and retransmission processing is performed.

  The third effect is that the above-mentioned confirmation response can be transmitted together with the transmission packet, so that the number of packets flowing on the network can be reduced and the response frequency of the confirmation response is improved. It can also be made.

  As a result, the load on the network can be reduced and the occurrence of packet transfer delay can be reduced as compared with the method of separately transmitting the transmission packet and the acknowledgment.

  The fourth effect is that, on the data transmission side, the probability of normal reception / abnormal reception (including arrival / non-arrival) for each packet on the data reception side can be grasped as a packet arrival rate for each transmission time zone. Therefore, the packet transmission time zone from the data transmission side to the data reception side can be finely adjusted.

  As a result, the data transmission side can select a time zone with the highest packet arrival rate, and perform more efficient packet transmission with a low retransmission frequency.

  Hereinafter, preferred embodiments of a packet retransmission method, a packet retransmission system, a packet retransmission program, and a program recording medium according to the present invention will be described with reference to the accompanying drawings. In the following description of the embodiments, the packet retransmission method according to the present invention will be described in detail. However, according to such description, embodiments of the packet retransmission system, the packet retransmission program, and the program recording medium according to the present invention can be easily performed. I won't go over these explanations.

(Configuration of Example)
FIG. 1 is a functional block diagram showing an example of the configuration of a data transmitting / receiving unit that implements a packet reproduction method according to the present invention. In FIG. 1, a data transmission unit 1 which is a packet transmission side continuously transmits packets via a network 3 to a data reception unit 2 which is a packet reception side using window control. The reception unit 2 transmits an acknowledgment regarding the received packet to the data transmission unit 1 via the network 3, so that the data transmission unit 1 determines whether the transmission packet has normally reached the data reception unit 2. Can be confirmed.

  In the configuration example shown in the functional block diagram of FIG. 1, the data transmission unit 1 includes a packet transmission control unit 11, a packet creation unit 12, a packet transmission unit 13, a transmission waiting packet holding unit 14, a transmission window management unit 15, and a transmitted packet. The holding part 16, the confirmation response waiting elapsed time monitoring part 17, the confirmation response reception control part 18, and the confirmation response receiving part 19 are provided at least.

  Here, the packet transmission control unit 11 controls the whole packet transmission operation whether or not to transmit a packet, and the packet creation unit 12 creates a transmission packet by inputting data to be transmitted. It is. The packet transmission unit 13 transmits the packet created by the packet creation unit 12 via the network 3 under the control of the packet transmission control unit 11.

  The transmission waiting packet holding unit 14 is a transmission waiting state in relation to the window size among the packets created by the packet creation unit 12, and holds packets that could not be transmitted under the control of the packet transmission control unit 11. is there. The transmission window management unit 15 manages a window size that can be transmitted, and notifies the packet transmission control unit 11 whether or not the number of transmitted packets has reached the window size on the transmission side.

  The transmitted packet holding unit 16 holds the already transmitted packet until a confirmation response is returned from the data receiving unit 2 under the control of the packet transmission control unit 11. The confirmation response waiting elapsed time monitoring unit 17 manages the acknowledgment response waiting timer 101 under the control of the packet transmission control unit 11 and manages the waiting time for the confirmation response from the data receiving unit 2 side for the transmitted packet. It is. The confirmation response receiving unit 19 receives the confirmation response from the data receiving unit 2 side via the network 3.

  The confirmation response reception control unit 18 receives a confirmation response from the data reception unit 2 side by the confirmation response reception unit 19, and confirms that the confirmation packet is held in the transmitted packet holding unit 16 under the control of the packet transmission control unit 11. In addition to performing processing corresponding to the response, the packet transmission control unit performs transmission processing related to the transmission waiting packet held in the transmission waiting packet holding unit 14 in relation to the window size and the transmission packet newly created by the packet creation unit 12 11 is notified.

  On the other hand, the data reception unit 2 in FIG. 1 includes a packet reception control unit 21, a packet reception unit 22, a data processing unit 23, a reception window management unit 24, a confirmation response reply waiting elapsed time monitoring unit 25, a confirmation response transmission control unit 26, At least an acknowledgment transmission unit 27 is provided.

  Here, the packet reception control unit 21 controls the entire packet reception operation, and the packet reception unit 22 receives data from the data transmission unit 1 via the network 3 under the control of the packet reception control unit 21. Packets continuously transmitted via the network 3 are received. The data processing unit 23 performs processing of rearranging the order of received packets under the control of the packet reception control unit 21, arranging them in numerical order, and assembling the original data.

  The reception window management unit 24 manages the window size on the reception side and manages the reception status of packets. Whether the number of received packets has reached the window size on the reception side with respect to the packet reception control unit 21. Notify. The acknowledgment reply waiting elapsed time monitoring unit 25 manages the acknowledgment reply waiting timer 201 based on the control of the packet reception control unit 21 and manages the waiting time until the acknowledgment reply is sent.

  The confirmation response transmission control unit 26 controls whether or not to transmit a confirmation response to the packet received from the data transmission unit 1 under the control of the packet reception control unit 21. The confirmation response transmission unit 27 transmits the confirmation response to the data transmission unit 1 side via the network 3.

  FIG. 2 is a format diagram showing an example of a format of an acknowledgment used in the packet retransmission method according to the present invention. As shown in FIG. 2, the confirmation response 300 in this embodiment includes a reception confirmation sequence number 301 for notifying the data transmission unit 1 side of how many packets until the serial number has been normally received, and this confirmation response 300. Packet information number 302 indicating how many response information about each packet after the packet that could not be normally received by the data transmission unit 1 side, and each serial number packet after the packet that could not be received normally It includes at least information on packet arrival status 303 representing response information on normal reception / abnormal reception (including arrival / non-arrival) for each.

  Here, the packet arrival status 303 indicates that the normal transmission / abnormal reception information of the packets related to all serial numbers after the first packet that has been abnormally received even when the first packet cannot be normally received. As much information as the window size is necessary so that it can be transmitted to one side. In the example shown in FIG. 2, the window size is N (N: integer).

(Description of operation of the embodiment)
Next, an example of the operation of the data transmission unit 1 and the data reception unit 2 shown in FIG. 1 to which the packet retransmission method according to the present invention is applied will be described with reference to FIGS. FIG. 3 is a sequence diagram for explaining an example of a packet transmission / reception operation in the packet retransmission method according to the present invention. An example of a sequence when the transmitted packet does not reach the data receiving unit 2 is shown. Show.

  FIG. 4 is a sequence diagram for explaining a different example of the packet transmission / reception operation in the packet retransmission method according to the present invention. When the arrival order of the packets arriving at the data receiving unit 2 side is changed in the network 3. An example of the sequence is shown. 3 and 4, the network 3 interposed between the data transmission unit 1 and the data reception unit 2 is omitted for the sake of simplification, and the window size N in FIG. In the case of “6” (that is, when it is possible to transmit up to six packets continuously), FIG. 4 shows an example in which the window size N is “4”.

  In the sequence diagram of FIG. 3, the data transmission unit 1 continuously transmits the transmission packet 1 101p, the transmission packet 2 102p,..., The transmission packet 6 106p and the six packets indicated by the window size to the data reception unit 2. Although transmitted via the network 3, the transmission packet 3 103p and the transmission packet 5 105p have not arrived at the data reception unit 2 for some reason, so the confirmation response 1 101r indicating that from the data reception unit 2 is A case where the data is sent back to the data transmission unit 1 side via the network 3 is shown.

  By receiving the confirmation response 1 101r, the data transmission unit 1 needs to retransmit two transmission packets of the transmission packet 3 103p and the transmission packet 5 105p among the six transmission packets continuously transmitted previously. Before transmitting the next packet, the two packets, that is, retransmission packet 3 103pr and retransmission packet 5 105pr are transmitted again, and then the next transmission packet 7 107p and transmission packet 8 108p are transmitted. ing.

  On the other hand, in the sequence diagram of FIG. 4, the data transmission unit 1 continuously transmits four packets indicated by the window size from the transmission packet 10 110p to the transmission packet 13 113p to the data reception unit 2 via the network 3. Although the data has been transmitted, the arrival order of the transmission packet 11 111p and the transmission packet 12 112p is exchanged for some reason and arrives at the data reception unit 2. Therefore, the data reception unit 2 performs the arrival order exchange processing, In this example, a confirmation response 3 113r indicating that all the packets have been correctly received is returned from the reception unit 2 to the data transmission unit 1 via the network 3. By receiving the confirmation response 3 113r, the data transmission unit 1 recognizes that the four transmission packets that have been continuously transmitted first are normally received, and transmits the next transmission packet 14 114p. Yes.

  Next, an example of the packet transmission operation of the data transmission unit 1 shown in FIG. 1 will be described in detail with reference to the flowchart of FIG. FIG. 8 is a flowchart for explaining an example of a packet transmission operation in the packet retransmission method according to the present invention.

  In the flowchart of FIG. 8, first, the data transmission unit 1 suspends transmission when a packet to be transmitted is input or because of a window size indicating the number of packets that can be transmitted at one time. If there is a packet (YES in step S1), the transmission window management unit 15 has already transmitted without receiving a confirmation response from the data reception unit 2 side in order to determine whether the transmission window can still be transmitted. The number of packets (number of transmitted packets) is confirmed (step S2).

  If the number of transmitted packets is within the number of packets that can be transmitted at the same time, that is, within the window size (YES in step S2), the next packet can be transmitted and is sent to the data receiving unit 2 via the network 3. Then, a process of transmitting one packet is performed (step S3). Thereafter, the transmitted packet holding unit 16 holds the transmitted packet until an acknowledgment for the transmitted packet is returned, and the acknowledgment waiting elapsed time monitoring unit 17 waits until the acknowledgment for the transmitted packet arrives. In order to monitor the time, a confirmation response reception waiting timer 101 for counting a predetermined time is started. Further, the transmission window management unit 15 adds one to the number of transmitted packets.

  On the other hand, if the number of transmitted packets has already reached the window size (NO in step S2), no further packet transmission can be performed, so the transmission waiting packet holding unit 14 determines the packet to be transmitted. It is suspended as a transmission waiting packet (step S7).

  Next, after the packet transmission process or the packet hold process, the confirmation response reception unit 19 confirms reception of the confirmation response (step S4). As a result, when the confirmation response is received (YES in step S4), the confirmation response reception control unit 18 confirms the arrival status on the data reception unit 2 side of the transmitted packet corresponding to the received confirmation response, and transmits the transmitted packet. When the response information indicating normal reception / abnormal reception is included, the confirmation response waiting elapsed time monitoring unit 17 clears the confirmation response reception waiting timer 101 for the transmitted packet.

  Here, if normal arrival at the data receiving unit 2 side cannot be confirmed and it is determined that there is a packet that needs to be retransmitted (YES in step S5), the transmitted packet holding unit 16 holds the packet. The transmitted pending packet corresponding to the packet that needs to be retransmitted is extracted from the transmitted transmitted pending packets, the retransmission process is prepared (step S6), and the process returns to step S3 to retransmit the packet.

  On the other hand, with respect to a packet for which normal arrival confirmation on the data receiving unit 2 side has been completed, the transmitted pending packet held in the transmitted packet holding unit 16 is discarded (step S9), and the process returns to step S1. The process returns to the process of determining whether there is a packet to be transmitted. In addition, the transmission window management unit 15 subtracts the number of packets that have been confirmed to be normal among the transmitted packets from the number of transmitted packets.

  However, even if there is a packet for which normal arrival confirmation has been made on the data receiving unit 2 side, there may be a case where the subtraction process for the number of transmitted packets is not performed. In other words, if there is a packet that has not been successfully received on the data receiving unit 2 side and there is at least one packet that has not been confirmed for normal arrival, the normal arrival confirmation can be performed. For packets with serial numbers after the packet that did not exist, even if there was a packet that could be normally reached on the data receiver 2 side, the packet after the packet that could not be normally reached was counted from the number of transmitted packets. No subtraction is performed.

  Further, after the packet transmission process or the packet hold process, if the confirmation response receiving unit 19 does not receive the confirmation response (NO in step S4), the confirmation response waiting elapsed time monitoring unit 17 The reception waiting timer 101 is confirmed (step S8). If there is a transmitted pending packet for which the acknowledgment response waiting timer 101 has timed out (YES in step S8), the process proceeds to step S6, and the normal arrival to the data receiving unit 2 described above is confirmed. As in the case where the packet cannot be retransmitted, it is determined that there is a packet that needs to be retransmitted, and the transmitted pending packet corresponding to the packet that needs to be retransmitted is extracted from the transmitted pending packets to prepare for retransmission processing. , Perform retransmission processing.

  On the other hand, if there is no transmitted pending packet for which the acknowledgment response waiting timer 101 times out (NO in step S8), the process returns to step S1 to determine whether there is a packet to be transmitted. Return to.

  Next, an example of the packet reception operation of the data reception unit 2 shown in FIG. 1 will be described in detail with reference to the flowchart of FIG. FIG. 9 is a flowchart for explaining an example of a packet receiving operation in the packet retransmission method according to the present invention.

  In the flowchart of FIG. 9, first, the data reception unit 2 confirms reception of a packet (step S11). If a packet has been received (YES in step S11), the packet reception unit 22 performs packet reception processing under the control of the packet reception control unit 21, and the data reception unit 23 confirms the arrival order of the received packets. I do. That is, in the network 3, it is confirmed whether or not the packet order is exchanged for some reason such as a difference in the packet transfer route (step S12). If the packet order has been changed and arrived (YES in step S12), the data processing unit 23 performs a packet order changing process (step S16).

  Next, the reception window management unit 24 adds 1 to the number of received packets. Here, if the sequence number of the packet received this time is discontinuous from the sequence number of the packet received last time and the number jumped to the old number side, instead of adding “1”, “ The number of lost packets + 1 ”is added as the number of received packets. On the other hand, when the packet order is changed and a packet having a sequence number lower than the sequence number that has already arrived is reached, the number of received packets is not added.

  When the number of received packets has reached the window size (YES in step S13), the confirmation response transmission unit 27 returns a confirmation response to the data transmission unit 1 that has transmitted the packet, and the acknowledgment response waiting elapsed time The monitoring unit 25 clears the confirmation response reply waiting monitoring timer 201 corresponding to the packet that has returned the confirmation response (step S14).

  In this confirmation response, as shown in FIG. 2 described above, the reception confirmation serial number 301 is used to tell how many serial numbers have been correctly received. If the packet cannot be received normally and a packet dropout occurs. In addition, after the missing packet, the number of packet information 302 indicating how many packets of response information are returned in the confirmation response, the serial number after the missing packet, that is, the packet that could not be normally received. Each information of packet arrival status 303 representing response information of normal reception / abnormal reception (including arrival / non-arrival) of each individual packet is included.

  When the confirmation response is returned in step S14, the reception window management unit 24 subtracts the number of confirmation response returned packets from the number of received packets. However, if there is a packet that could not be received normally and a packet loss occurred, the number of serial number packets before the packet loss is treated as the number of packets that have been acknowledged. For packets with serial numbers after missing packets, even if a confirmation response indicating that the packet was successfully received is sent back to the data transmission side, it will not be treated as a confirmation response reply packet, Then, it is determined whether or not the packet is a reply target reply.

  If the number of received packets has not reached the window size (NO in step S13), the confirmation response return waiting time monitoring unit 25 confirms the response for counting a predetermined time with respect to the received packets. The reply waiting monitoring timer 201 is started, the process returns to step S11, and the process returns to the reception determination process for the next packet.

  In step S11, when there is no received packet (NO in step S11), the confirmation response reply waiting time monitoring unit 25 confirms the confirmation response reply wait monitoring timer 201 (step S15). If there is a packet for which the acknowledgment reply waiting timer 201 has timed out (YES in step S15), the process proceeds to step S14 in the same manner as when the window size is reached, and the acknowledgment reply waiting elapsed time is reached. The monitoring unit 25 clears the confirmation response reply waiting monitoring timer 201, and returns a confirmation response to the data transmission unit 1 that has transmitted the packet (step S14).

  In step S15, if there is no packet for which the acknowledgment reply wait timer 201 times out (NO in step S15), the process returns to step S11 and returns to the reception determination process for the next packet.

  Next, the specific sequence diagrams illustrated in FIGS. 3 and 4 will be described in more detail with reference to an example of the confirmation response format shown in FIGS. 5 is a packet format showing an example of the format of the confirmation response 1 101r in the sequence diagram of FIG. 3, and FIG. 6 is a packet format showing an example of the format of the confirmation response 2 102r in the sequence diagram of FIG. 7 is a packet format showing an example of the format of confirmation response 3 113r in the sequence diagram of FIG.

  3 and 4, “i” in “transmission packet i” (i = 1, 2, 3,...) Represents a packet sequence number, and transmission packet 1 represents a packet with sequence number 1.

  First, the sequence diagram of FIG. 3 will be described. FIG. 3 illustrates the operation when the packet cannot be normally received and the received packet is dropped when the window size is 6 as described above. The data transmission unit 1 continuously transmits six packets from the transmission packet 1 101p corresponding to the window size to the transmission packet 6 106p. Here, the number of transmitted packets is six for the window size. In addition, when the transmission packet 1 is transmitted, the confirmation response reception wait timer 101 is started as a reception wait timer for waiting for the confirmation response.

  Assume that the transmission packet 3 103p and the transmission packet 5 105p have not arrived at the data reception unit 2 now. The data reception unit 2 recognizes that the transmission packet 3 103p has been lost when the transmission packet 4 104p is received next to the transmission packet 2 102p, and the transmission packet 1 101p and the transmission packet 2 that have been normally received are received. The number of received packets is set to four by further adding two up to the normally received transmission packet 4 104p, including the transmission packet 3 103p in which packet loss has occurred, to the two at 102p.

  At this point in time, since the number of received packets has not yet reached six for the window size, the confirmation operation is not returned and the subsequent packet reception operation is continued. Subsequently, when the transmission packet 6 106p is received, it is recognized that the transmission packet 5 105p is further lost. Similarly to the case where the transmission packet 4 104p is received next to the transmission packet 2 102p, when the transmission packet 6 106p is received, the number of received packets is further increased by 2 to be 6. In other words, the data receiving unit 2 actually receives only 4 packets, but determines that the number has reached 6 for the window size, and returns a confirmation response 1 101r.

  The format of the confirmation response 1 101r returned in the sequence of FIG. 3 is as follows. As shown in FIG. 5, the reception confirmation sequence number 401 is 2, the packet information number 402 is 4, and packets up to the sequence number 2 are received normally. The packet data transmission unit 1 side is notified that the response information indicating the packet arrival statuses 403, 404, 405, and 406 of the individual packets is included for the four packets after the serial number 3. .

  Here, the packet arrival status 403 of the packet 3 103p contains response information indicating that the transmission packet 3 103p did not normally reach the data receiving side, and the packet arrival status 404 of the packet 4 104p contains the transmission packet 4 104p. Response information indicating that the message has arrived normally. The packet arrival status 405 of the packet 5 105p includes response information indicating that the transmission packet 5 105p did not arrive normally, and the packet arrival status 406 of the packet 6 106p indicates that the transmission packet 6 106p arrived normally. Contains information.

  After that, the number of received packets is 2 for the transmission packet 1 101p and the transmission packet 2 102p as the number of consecutive packets continuously received from the first transmission packet 1 101p. Is subtracted to obtain 4. The number of received packets is less than 6 for the window size, and the subsequent packets can be received. The data transmission unit 1 that has received the confirmation response 1 101r clears the confirmation response reception waiting timer 101 that has been monitoring the reception of the confirmation response, and among the transmitted packets, the transmission packet 3 103p and the transmission packet 5 Recognizing that 105p did not reach normally, only the transmission packet 3 103pr and the transmission packet 5 105pr are retransmitted.

  At the same time, it is assumed that transmission packet 1 101p and transmission packet 2 102p have received normal acknowledgments, and the number of transmitted packets is subtracted from 6 to 4 to obtain 4 and subsequent transmission packet 7 107p Two transmission packets 8 and 108p are set in a state where they can be transmitted as two packets that the window size allows. The data reception unit 2 that has normally received the retransmission transmission packet 3 103pr, the retransmission transmission packet 5 105pr, the transmission packet 7 107p, and the transmission packet 8 108p transmitted in this manner returns an acknowledgment 2102r.

  The format of the confirmation response 2 102r to be returned in the sequence of FIG. 3 is that the reception confirmation sequence number 407 is 8 and the packet information number 408 is 0, as shown in an example in FIG. The data transmission unit 1 is notified that there is no packet that has been received and could not be received normally.

  Next, the operation when the window size is 4 and the order of packets received by the data receiving unit 2 is switched on the network 3 will be described with reference to FIG.

  The data transmission unit 1 continuously transmits four packets of a transmission packet 10 110p, a transmission packet 11 111p, a transmission packet 12 112p, and a transmission packet 13 113p corresponding to the window size. Now, it is assumed that the transmission packet 11 111p and the transmission packet 12 112p are switched on the network 3 and transmitted to the data reception unit 2. The data receiving unit 2 recognizes that the transmission packet 11 111p has been lost when the transmission packet 12 112p is received after the transmission packet 10 110p.

  However, at this time, immediately, the acknowledgment process requesting retransmission of the transmission packet 11 111p is not returned to the data transmission unit 1 and reception processing of subsequent packets is continued until the window size 4 is reached.

  Thereafter, when the transmission packet 11 111p is received, a process of switching the order of the transmission packet 12 112p and the transmission packet 11 111p is performed. At the time when the transmission packet 13 113 is received, the data reception unit 2 assumes that all four packets from the transmission packet 10 110p to the transmission packet 13 113p are normally received, and sends an acknowledgment 3 113r to the data transmission unit 1. Reply.

  The format of the confirmation response 3 113r returned in the sequence of FIG. 4 is as follows. As shown in FIG. 7, the reception confirmation sequence number 409 is 13, the packet information number 410 is 0, and packets up to the sequence number 13 are received normally. The data transmission unit 1 is notified that there is no packet that has been received and could not be received normally.

(Features of this embodiment)
As described in detail above, the features of the present invention in this embodiment are as follows.

  First, in communication for packetizing data and transmitting / receiving data, for example, UDP / IP (User Datagram Protocol / Internet Protocol) communication, the data transmission side continuously transmits a plurality of packets using window control, and the data When the receiving side returns a confirmation response to inform the data transmission side of the packet that has arrived normally, it has been received after the serial number in which one packet cannot be received normally and a packet dropout occurred. Alternatively, by sending back information on normal reception / abnormal reception (including arrival / not-arrival) of each of one or more packets expected to be received, the data transmission side reaches which data packet, It is possible to know exactly which packet has not arrived, and It lies in that it possible to perform retransmission processing.

  The second point is that when the data receiving side detects a missing packet, it does not immediately send a retransmission request to the data transmitting side, and continues to receive the next packet. Even when the order is changed and arrives at the data reception side, unnecessary retransmission processing can be avoided by performing packet replacement processing at the data reception side.

  Further, the features of the present invention in this embodiment will be described repeatedly with reference to FIGS. 3 and 4 described above.

  The first feature is the same as that described with reference to FIG. In FIG. 3, assuming that the number of packets (window size) that can be transmitted at one time is 6, the data transmission unit 1 sends six packets corresponding to the window size to the data reception unit 2 from transmission packet 1 101p to transmission packet 6 106p. Send continuously. Now, assuming that the transmission packet 3 103p and the transmission packet 5 105p did not reach the data reception unit 2, the data reception unit 2 received normally up to the transmission packet 2 102p out of 6 packets, and a packet loss occurred. For transmission packet 3 103p and later, as information indicating normal reception / abnormal reception for each packet, response information indicating that transmission packet 4 104p and transmission packet 6 106p have arrived normally but transmission packet 5 105p has not been reached is also received. In addition, it is sent back to the data transmission unit 1 as a confirmation response 1 101r.

  Upon reception of the confirmation response 1 101r, the data transmission unit 1 recognizes that the transmission packet 3 103p and the transmission packet 5 105p among the transmitted six packets did not reach the data reception unit 2, and the transmission packet 3 103p And the transmission packet 5 105p are retransmitted.

  The second feature described above is the same as that described with reference to FIG. In FIG. 4, the number of packets that can be transmitted at one time (window size) is set to 4, and the data transmission unit 1 continuously transmits 4 packets corresponding to the window size to the data reception unit 2. Now, assuming that the order of the transmission packet 11 111p and the transmission packet 12 112p is switched on the network 3 and reaches the data reception unit 2, the data reception unit 2 receives the transmission packet 12 112p after the transmission packet 10 110p. At this point, although it is recognized that the transmission packet 11 111p has been lost, the subsequent packet is continuously received without returning an acknowledgment requesting the retransmission of the transmission packet 11 111p to the data transmission unit 1. Continue state.

  After that, when the transmission packet 11 111p is received, the process of switching the order of the received transmission packet 12 112p and the transmission packet 11 111p is performed, and the data transmission unit 1 has received all packets normally. By returning the confirmation response 3 113r to be performed, unnecessary retransmission processing is avoided.

(Effect of this embodiment)
The effects of the present invention in the present embodiment having the above characteristics are typified by the following points.

  The first effect is that the data reception side receives the number of packets with the full window size for a plurality of transmitted packets, or when a predetermined time elapses, it cannot be received normally and a dropout occurs. For each packet with a serial number after the received packet, the data transmission side sends back a plurality of packets transmitted by returning the arrival status (normal reception / abnormal reception information) of each packet in one confirmation response. Among these, it is possible to identify a packet that has not been normally received by the data receiving side, and it is possible to retransmit only a packet that has not normally reached the data receiving side.

  As a result, the number of retransmitted packets can be reduced and the load on the network can be reduced as compared with the conventional method that requires retransmission of all packets after the first packet that did not arrive normally. Compared to the method in which the arrival status for all transmitted packets is sent back as a confirmation response, only the arrival status for the sequential packets after the first packet that did not arrive normally is sent back as a confirmation response. This reduces the amount of information and increases the speed of retransmission processing. This effect increases as the number of packets (window size) transmitted and received continuously at a time increases.

  The second effect is that when the order of the packets is reversed and reaches the data receiving side on the network for transferring the packet, the data receiving side receives the old number side packet first, so that the packet is lost. As soon as it is determined that the packet has occurred, it does not immediately send back an acknowledgment requesting retransmission, and receives the number of packets that are full of the window size, or continues until a predetermined time elapses. Therefore, when a packet whose order has been changed arrives normally, the data receiving side can perform the order changing process and send a confirmation response requesting retransmission. No need to reply to the side.

  As a result, when the packet order is reversed, unnecessary retransmission processing can be reduced as compared with the conventional method in which a retransmission request confirmation response is immediately returned to the data transmission side and retransmission processing is performed.

(Another embodiment of the present invention)
Next, another embodiment of the present invention will be described with reference to FIG. FIG. 10 is a sequence diagram for explaining a further different example of the packet transmission / reception operation in the packet retransmission method according to the present invention, and illustrates a method of returning an acknowledgment in the packet retransmission method according to the present invention.

  In the above-described embodiment, when receiving the transmission packet, the data receiving unit 2 returns only the confirmation response regarding the received packet to the data transmitting unit 1 side that has transmitted the packet. In the present embodiment, when there is transmission data from the data reception unit 2 to the data transmission unit 1 side, the transmission packet 31 131p transmitted from the data reception unit 2 to the data transmission unit 1 is related to the received packet. Send information including confirmation response information. That is, the transmission packet 31 131p functions as a transmission packet and confirmation response.

  As described above, by acknowledging the acknowledgment to the transmission packet, the number of packets flowing on the network can be reduced, and the network load can be reduced. In addition, since it is possible to increase the response frequency of acknowledgments by sharing the acknowledgment packet with the transmission packet, the data transmission side can shorten the time until the acknowledgment response to the transmission packet is received. Packet transmission / reception is possible.

  That is, since it is possible to transmit the acknowledgment response together with the transmission packet, the number of packets flowing on the network can be reduced, and the response frequency of the acknowledgment response can be improved. Compared with the method of separately transmitting the acknowledgment, it is possible to reduce the load on the network and reduce the occurrence of packet transfer delay.

  As another example, a method of collecting packet arrival rate on the network (that is, packet arrival rate to the data receiving side) and adjusting packet transmission timing will be described.

  In the conventional method, as described above, when the packet loss occurs, the data transmission unit 1 cannot know the packet arrival status regarding the continuously transmitted packets thereafter. However, in the acknowledgment method according to the present invention, the data transmission side can confirm the arrival status of all transmitted packets, so information on whether or not each packet has arrived at the data reception side can be determined by time zone. It becomes possible to grasp accurately. That is, based on the information of the acknowledgment response, collect the statistical information of the packet arrival rate for each time zone indicating the rate at which the transmitted packets reached the data receiving side, and It is possible to adjust the packet transmission time zone for the receiving side.

  In this way, on the data transmission side, the packet transmission time zone from the data transmission side to the data reception side can be finely adjusted based on the packet arrival rate statistical information. By selecting the highest time zone, the frequency of retransmission is low and more efficient packet transmission can be performed.

  The configuration of the preferred embodiment of the present invention has been described above. However, it should be noted that such examples are merely illustrative of the invention and do not limit the invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention.

It is a functional block diagram which shows an example of a structure of the data transmission / reception part which implement | achieves the packet reproduction | regeneration method by this invention. It is a format figure which shows an example of the format of the confirmation response used in the packet resending system by this invention. It is a sequence diagram for demonstrating an example of the transmission / reception operation | movement of the packet in the packet retransmission system by this invention. It is a sequence diagram for demonstrating a different example of the transmission / reception operation | movement of the packet in the packet retransmission system by this invention. It is a packet format which shows an example of the format of the confirmation response 1 in the sequence diagram of FIG. It is a packet format which shows an example of the format of the confirmation response 2 in the sequence diagram of FIG. 5 is a packet format showing an example of a format of confirmation response 3 in the sequence diagram of FIG. 4. 5 is a flowchart for explaining an example of a packet transmission operation in the packet retransmission method according to the present invention. 5 is a flowchart for explaining an example of a packet reception operation in the packet retransmission method according to the present invention. It is a sequence diagram for demonstrating the further different example of the transmission / reception operation | movement of the packet in the packet retransmission system by this invention.

Explanation of symbols

1 Data transmission unit 101 Confirmation response reception waiting timers 101p, 102p, ..., 106p Transmission packets 1, 2, ..., 6
103pr, 105pr resent packets 3, 5
101r, 102r confirmation response 1, 2
11 Packet transmission control unit 110p, ..., 113p, 114p Transmission packet 10, ..., 13, 14
113r Confirmation response 3
12 packet creation unit 13 packet transmission unit 14 transmission waiting packet holding unit 15 transmission window management unit 16 transmitted packet holding unit 17 confirmation response waiting elapsed time monitoring unit 18 confirmation response reception control unit 19 confirmation response reception unit 2 data reception unit 201 confirmation Response reply waiting timer 21 Packet reception control unit 22 Packet reception unit 23 Data processing unit 24 Reception window management unit 25 Confirmation response reply waiting time monitoring unit 26 Confirmation response transmission control unit 27 Confirmation response transmission unit 3 Network 300 Confirmation response 301 Reception confirmation Serial number 302 Packet information number 303 Packet arrival status 401, 407, 409 Reception confirmation serial number 402, 408, 410 Packet information number 403, 404, 405, 406 Packet arrival status,

Claims (12)

  When the data transmission side continuously transmits a plurality of packets to the data reception side via the network using the window control, the data reception side normally receives the packets transmitted continuously via the network. When sending back a confirmation response notifying the data transmission side whether or not it has been received, if a packet drop is detected due to an abnormal reception, the packet in which the packet drop occurred is included in one reply reply By returning the number of previously normally received packets and the information on normal reception / abnormal reception regarding each of one or more packets after the sequence number of the packet in which the packet loss has occurred, the data transmission side A packet retransmission method for retransmitting only a serial number packet that has been abnormally received on the data receiving side.   When the data receiving side receives a packet with a serial number that is older than the serial number sequence, it immediately continues receiving the subsequent packet without returning an acknowledgment indicating that the packet has been dropped to the data transmitting side. In addition, the packets on the weak number side are normally received behind the old number side serial number packets received earlier, and all the packets to be received are prepared by the process of replacing the serial number of the received packets. 2. The packet retransmission method according to claim 1, wherein when the data is found, a confirmation response indicating that the data has been normally received is returned to the data transmission side.   The timing at which the data receiving side returns the confirmation response to the data transmitting side is a predetermined time after receiving the number of packets corresponding to the window size or after receiving the first packet in which no confirmation response is returned. The packet retransmission method according to claim 1, wherein the packet retransmission method is one of cases in which the time has elapsed.   If there is a transmission packet to be transmitted to the data transmission side on the data reception side, the confirmation response is added to the transmission packet to be transmitted to the data transmission side and returned to the data transmission side. 4. The packet retransmission method according to claim 1, wherein the packet retransmission method is performed.   Based on the confirmation response, the data transmission side grasps normal reception / abnormal reception of each packet transmitted / received to / from the data reception side via the network according to a time zone, and transmits the packet to the data reception side. 5. The packet retransmission method according to claim 1, wherein the time zone can be adjusted.   When the data transmission unit continuously transmits a plurality of packets to the data reception unit via the network using the window control, the data reception unit normally transmits the packets transmitted continuously via the network. When sending back a confirmation response notifying the data transmission unit whether or not the packet has been received, if a packet drop is detected due to abnormal reception, a packet drop occurs in one reply reply The data transmission is performed by returning the number of normally received packets before the received packet and the normal reception / abnormal reception information regarding each of one or more packets after the serial number of the packet in which the packet loss occurred. The packet retransmission system, wherein the unit retransmits only the serial number packet that is abnormally received by the data reception unit.   When the data receiving unit receives a packet with a serial number on the older side than the sequence of the serial number, immediately after that, without receiving a confirmation response indicating the packet loss to the data transmitting unit, the receiving process of the subsequent packet is performed. Continue to receive normally the weak-numbered packet that was reversed by the old-numbered serial number packet that was received earlier, and receive all the packets that should be received by replacing the serial number of the received packet The packet retransmission system according to claim 6, wherein when it is determined that the packet has been received, a confirmation response indicating that the data has been normally received is returned to the data transmission unit.   The timing at which the data reception unit returns the confirmation response to the data transmission unit is determined in advance when the number of packets corresponding to the window size is received or after the first packet in which no confirmation response is returned is received. The packet retransmission system according to claim 6, wherein the packet retransmission system is a case where time has elapsed.   In the data reception unit, when there is a transmission packet to be transmitted to the data transmission unit, the confirmation response is combined with the transmission packet to be transmitted to the data transmission unit, and the data transmission unit The packet retransmission system according to claim 6, wherein the packet retransmission system is returned.   Based on the confirmation response, the data transmission unit grasps the normal reception / abnormal reception of each packet transmitted / received to / from the data reception unit via the network according to the time zone, and transmits the packet to the data reception side. The packet retransmission system according to any one of claims 6 to 9, wherein a transmission time zone can be adjusted.   6. A packet retransmission program that implements the packet reproduction method according to claim 1 as a program executable by a computer.   A program recording medium, wherein the packet reproduction program according to claim 11 is recorded on a computer-readable recording medium.

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