JPH11298525A - Network node device, terminal equipment and gateway device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time for re-reception by directly knowing the information on packet destruction by analyzing information in a header part of a packet received from the side of a transmission terminal, specifying the header part, a data part and a trailer part of the packet and constituting a data lost packet. SOLUTION: At a network node device 100, the packet sent from the side of transmission is received by a reception function 101 and enters a packet constitution analytic part specifying function 103. In this case, when the packet shows abnormality or congestion, the packet sends a packet abnormal signal 121 from the constitution analytic part specifying function 103 to an abnormality control function 106. The congestion is detected by a transmission function 102 and sent to the abnormality control function 106. Based on these information, the abnormality control function 106 sends control signals 122 and 123 to a data lost packet constituting function 105 and an input changeover switch 104 and controls these components. Besides, the congestion state of the network can be speedily canceled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for transmitting and receiving information on a computer network such as a LAN and the Internet.

[0002]

2. Description of the Related Art On a computer network, when a packet is transmitted between two or more terminals, congestion occurs when an amount of information exceeding a band is transmitted from each terminal to a specific route. On the route where congestion has occurred, packets are discarded due to excess bandwidth. In this case, the packet does not arrive at the receiving terminal, and the terminal has no means of knowing what has happened on the network.

FIG. 1 is a diagram illustrating packet transmission on a network when a timeout is used as a trigger for retransmission of a packet. The packet is transmitted on the network from the transmitting terminal to the receiving terminal via a relay device such as a router. The numbers in the figure are assigned to segments that are packet transmission data units. Time change progresses from top to bottom. The arrow indicates the flow of the packet, and n, n + 1,... Below the arrow indicate the acknowledgment number ACK included in the header of the packet. In segment 1 n
It is.

[0004] First, the packet of segment 1 is transmitted toward the receiving terminal. When this packet is normally received by the receiving terminal, the receiving terminal returns n to the transmitting terminal in segment 2. Transmission / reception proceeds in the same manner as above, but when the packet is discarded by the relay device in the network and is not transmitted normally as in segment 3, and the discarded packet is retransmitted from the transmitting terminal side, the set timeout is triggered. Becomes Retransmission is performed only when a response acknowledgment of packet arrival has not been sent before the timeout. In FIG. 1, the packet sent in segment 11 is the retransmission of the packet in segment 3.

[0005] FIG. 2 is a diagram for explaining packet transmission on a network when receiving duplicate ACKs as a trigger for packet retransmission. The flow of the packet transmission and each symbol in the figure conform to FIG. When the packet is discarded by the relay device in the network in the segment 3 and is not transmitted normally, the receiving terminal side acknowledges the ACK of the last packet of the continuous segment that has completed normal reception.
Is returned to the transmitting terminal. In FIG. 2, in segment 4, n + 1 of segment 2 is sent to the transmitting terminal side. The transmitting terminal counts this number, and when the same number is received, retransmits the packet assuming that the packet has been discarded. In FIG. 2, the number of counts is set to three, and the count is performed in segments 4, 7, and 10, respectively. In the figure, the packet sent in segment 11 is the retransmission of the packet in segment 3.

[0006]

In such a conventional packet transmission method, the entire packet is discarded, and it is not possible for the transmitting / receiving terminal to directly know the information on the discarded packet. Therefore, the conventional retransmission method using a timeout of ACK reception or reception and retransmission of duplicate ACK as a trigger has a problem that a long time is required.

In view of the above problems, an object of the present invention is to provide a network node capable of directly recognizing information that a packet has been discarded in a terminal device and shortening retransmission time. A device, a terminal device, and a gateway device are provided.

[0008]

In order to achieve the above object, a network node device of the present invention analyzes information of a header portion of a packet arriving from a transmitting terminal, and analyzes a header portion, a data portion, and a trailer of the packet. It has a function of specifying a section, a function of discarding a data section to form a data lost packet from a remaining header section and a trailer section, and a function of transmitting a data lost packet to a receiving terminal.

Another network node device of the present invention comprises:
A function to identify the header, data, and trailer of the packet by analyzing the information in the header of the packet arriving from the transmitting terminal, construct a data lost packet from the remaining header and trailer by discarding the data The ability to
In addition, it has a function of exchanging the transmission destination address and the transmission source address of the header portion of the data lost packet to change the transmission destination to the transmission terminal, and sending back the data lost packet to the transmission terminal side.

Further, the terminal device of the present invention has a function of specifying a header portion, a data portion, and a trailer portion of a packet received from a network, comparing the original size of the packet with the size of the received packet, and Has a function of discriminating a lost data packet in which the data part is missing, and a function of returning information of discarding the data part of the packet to the transmitting terminal side using the acknowledgment number field of the header part. Features.

[0011] The terminal device of the present invention further has a function of, when receiving information of discarding the data portion of the packet from the receiving terminal side, a function of performing the retransmission processing of the packet with the highest priority or a data lost packet being returned. It is desirable to have a function of determining this when it comes, and performing the retransmission processing of the packet with the highest priority.

[0012] The gateway device of the present invention is located between the terminal device and the network node device, and when the number of data lost packets returned from the network node device to the transmitting terminal side exceeds a predetermined number, It has a function of stopping transmission of a packet sent from the transmitting terminal to the receiving terminal for a predetermined time.

According to the present invention, the data section of the packet in the network node device such as a router is discarded by the function of grasping the configuration of the header section, the data section, and the trailer section of the packet. And a data lost packet including a trailer unit. At this time, the packet size of the header part is corrected to a value excluding the data part. The process of returning the data lost packet to the transmission source is performed by exchanging the addresses of the transmission source and the transmission destination.

The receiving terminal determines whether or not the received packet is a data lost packet by comparing the actual size of the received packet with its original size. If the compared sizes are equal, it is determined that the packet is normal, and if the actual size is smaller than the original size, it is determined that the data part is a lost data packet whose data part has been discarded. The actual size of the packet is obtained from the header field, and the original size of the packet is obtained from the difference between the ACK of the header and the ACK of the header of the packet that arrived immediately before. If the received packet is normal, the receiving terminal returns an ACK of the packet. If the received packet is a data lost packet, the receiving terminal returns an ACK of the packet that arrived immediately before.

[0015] The retransmission process of the discarded packet at the transmitting terminal is triggered by receiving two ACKs of the same number from the receiving terminal or receiving a data lost packet from a network node device such as a router. . The determination of the lost data packet conforms to the function of the receiving terminal.

When the network node device functions as a gateway device on the LAN, the process of stopping the transmission of the packet sent from the transmitting terminal is performed by the same trigger as the packet retransmission of the transmitting terminal. . At this time, the gateway device determines whether the arriving packet is a normal packet whose data part has not been discarded or a data lost packet.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 3, the transmission / reception packet includes a header section, a data section, and a trailer section. The header section has information such as a source address, an acknowledgment number ACK, and a packet size.

[Embodiment 1] A first embodiment of the present invention will be described with reference to FIGS. 4 is a diagram illustrating a configuration example of a network node device, FIG. 6 is a diagram illustrating a configuration example of a transmission terminal function of the terminal device, FIG. 8 is a diagram illustrating a configuration example of a reception terminal function of the terminal device, and FIG. FIG. 9 is a diagram showing a procedure for retransmitting a packet according to the first embodiment of the present invention.

In the network node device 100 shown in FIG. 4, the packet 111 sent from the transmitting side is received by the receiving function 101, and enters the packet structure analyzing section specifying function 103, where the packet is determined to be normal or abnormal. A determination is made. If the packet is normal and there is no congestion, the packet 113 is sent to the receiving side 112 via the input changeover switch 104 and the transmitting function 102. On the other hand, if the packet is abnormal or congested, the packet 114 is sent from the packet configuration analysis
The process proceeds to 105, where a data lost packet 115 is formed and sent to the receiving side 112 via the input changeover switch 104 and the transmitting function 102. In this case, a packet abnormality signal 121 is sent from the packet configuration analysis section identification function 103 to the abnormality control function 106. Congestion is detected by the sending function 102,
It is sent to the abnormality control function 106. The abnormality control function 106 sends control signals 122 and 123 to the data lost packet forming function 105 and the input switch 104 based on the information to control them.

In the transmission terminal function 300 of the terminal device shown in FIG. 6, the transmission data generated by the transmission data generation function 301 is transmitted to the receiving side 312 via the input / output switch 304 and the transmission function 302. On the other hand, when the reception function 303 receives the retransmission request packet 313 from the receiving side, the retransmission request packet 314 is sent to the retransmission request determination function 306, where it is determined whether data retransmission is necessary. When retransmission is required, a read control signal 321 is sent to the transmission data temporary holding function 305 and the input / output switch 30
4, a held data transmission switching control signal 322 is sent, the transmission data is read from the transmission data temporary holding function 305 by these control instructions, and transmitted to the receiving side 312 via the input / output switch 304 and the transmission function 302. Is done.

In the receiving terminal function 500 of the terminal device shown in FIG. 8, the packet 511 sent from the transmitting side is received by the receiving function 501, and enters the packet configuration analysis section specifying function 503, where the packet is normal. A determination is made as to whether there is an abnormality. If the packet is normal, the packet 512
Is sent to the reception data processing function 505. On the other hand, if the packet is abnormal, the abnormal packet 513 is transmitted from the packet configuration analysis section specifying function 503 to the data lost packet determination function 50.
4, and when it is confirmed that the packet is a data lost packet, a confirmation signal 521 is sent to the retransmission request function 506, and based on this, the retransmission request function 506 generates a retransmission request packet 514, and Packet 514 is a send function
It is sent to the sending side 515 via 502.

The transmission, reception and relay in FIG. 10 refer to the transmission terminal function (transmission terminal device) 300, the reception terminal function (reception terminal device) 500, and the network node device (for example, router) 100 of the present invention. The number indicates the segment number, and the value of ACK is n in segment 1.
This indicates that the packet of segment 3 has been discarded by the network node device.

When discarding a packet, the network node device 100 discards only the data portion, forms a data lost packet composed of a header portion and a trailer portion, and transmits this to the receiving terminal side. Receiving terminal device 500 receives this data lost packet and determines that the data portion of the packet has been discarded. In this case, the ACK value n of the last packet that has arrived normally is transmitted to the transmitting terminal side. Since the same value as the already received number has arrived, the transmitting terminal device 300 determines that the packet has been discarded, and retransmits the (n + 1) th packet in segment 5. In FIG. 7, the packet of segment 5 is segment 3
Is the retransmission of the packet.

In this embodiment, if the segment 3 is not transmitted, n which is immediately sent back from the receiving side in the segment 4 means a request for retransmission of the untransmitted data of the segment 3. As described above, since the retransmission request is issued directly from the untransmitted result, the transmitting side can immediately perform the retransmission processing upon receiving the segment 4 which is the retransmission request. As described above, in the packet transmission using the network node device and the terminal device of the present invention, the packet can be retransmitted without waiting for the timeout or the arrival of the overlapping ACK value. Can be shortened.

[Embodiment 2] FIG. 11 is a diagram for explaining a second embodiment of the present invention, and is a diagram showing a procedure for retransmitting a packet using a network node device according to the present invention and a terminal device according to the present invention. . The transmission, reception and relay in the figure are the same as in the case of FIG.
0, the receiving terminal device 500 and the network node device 10
Represents 0. The figure shows that the packet of the segment 3 has been discarded by the network node device 100. When discarding the packet, the network node device 100 discards only the data portion, forms a data lost packet including a header portion and a trailer portion, and transmits this to the receiving terminal side. Receiving terminal device 500 receives this data lost packet and determines that the data portion of the packet has been discarded.

In this case, at the time when the data lost packet arrives, the acknowledgment for the segments 1 and 2 has not been transmitted. Therefore, the value of the ACK value of the segment 2 when transmitting a response indicating that the packet of the segment 3 is discarded
Even if n + 1 is sent, the transmitting side terminal device 300 has received only one same value and cannot recognize the discard of the packet. The transmission informs the transmitting terminal 300 that the packet has been discarded, and the transmitting terminal 300 performs retransmission processing based on the notification. In FIG. 11, the packet of segment 6 is the retransmission of the packet of segment 3. Thus, in the packet transmission of the second embodiment using the network node device and the terminal device of the present invention,
As in the case of the first embodiment, the retransmission processing time can be reduced.

[Embodiment 3] A third embodiment of the present invention will be described with reference to FIGS. 5 is a diagram illustrating another configuration example of the network node device, FIG. 7 is a diagram illustrating another configuration example of the transmission terminal function of the terminal device, and FIG. 8 is a diagram illustrating a configuration example of the reception terminal function of the terminal device. FIG. 12 is a diagram showing a packet retransmission procedure according to the third embodiment of the present invention.

In the network node device 200 shown in FIG. 5, the packet 211 sent from the transmitting side is received by the receiving function 201, and it enters the packet configuration analysis section specifying function 203, where the packet is determined to be normal or abnormal. A determination is made. If the packet is normal and there is no congestion, the packet 213 is transmitted to the receiving side 212 via the transmitting function 202. On the other hand, if the packet is abnormal or congested, the packet 214 enters the data lost packet configuration function 205 from the packet configuration analysis section identification function 203, where a data lost packet 215 is formed. The address and the sender address are exchanged, and the data lost packet 216 is sent to the sender 217 via the sending function 204. In this case, a packet abnormality signal 221 is sent from the packet configuration analysis section specifying function 203 to the abnormality control function 206. The congestion is detected by the transmission function 202 and sent to the abnormality control function 206. Abnormality control function 206
Sends control signals 222 and 223 to transmission functions 204 and 202 based on the information to control them.

In the transmission terminal function 400 of the terminal device shown in FIG. 7, the transmission data 41 generated by the transmission data generation function 401 is transmitted.
1 is transmitted to the receiving side 412 via the input / output switch 404 and the transmitting function 402. On the other hand, when the receiving function 403 receives the data lost packet 413 from the receiving side, the data lost packet 414 is sent to the data lost packet determining function 406, where it is determined whether or not the packet is a data lost packet. If it is, it is determined that the previously transmitted transmission data needs to be retransmitted. When retransmission is required, a read control signal 421 is sent to the transmission data temporary holding function 405 and the input / output switch
A holding data transmission switching control signal 422 is sent to 404, and the transmission data is read out from the transmission data temporary holding function 405 according to these control instructions, and sent to the receiving side 412 via the input / output switch 404 and the transmission function 402. Is done.

The transmission, reception and relay in FIG. 12 represent the transmitting terminal 400, the receiving terminal 500 and the network node 200 of the present invention. FIG. 12 shows that the packet of the segment 3 is discarded by the network node device 200. The network node device 200 according to the present invention, when discarding a packet, discards only the data portion, forms a data lost packet composed of a header portion and a trailer portion, and changes the destination of the packet from the receiving terminal device 500 to the transmitting terminal. Change to device 400, and send back the data lost packet to the transmitting terminal side. The transmitting terminal 400 receives this, determines that the data portion of the packet has been discarded without receiving an ACK from the receiving terminal, and performs retransmission processing. In FIG. 12, the packet of segment 4 is a retransmission of the packet of segment 3. As described above, when the network node device and the terminal device of the present invention are used, the retransmission process can be performed without waiting for the notification of the packet discard from the receiving terminal device. Can be shortened.

Fourth Embodiment FIG. 13 is a diagram for explaining a fourth embodiment of the present invention, and is a diagram showing retransmission of a packet using a network node device according to the present invention and a terminal device according to the present invention. Transmission, reception and relay in the figure
Similarly to FIG. 12, a transmitting terminal 400, a receiving terminal 500, and a network node 200 of the present invention are shown.
FIG. 13 shows that the packet of the segment 3 has been discarded by the network node device 200. The network node device 200 according to the present invention, when discarding a packet, discards only the data portion, configures a data lost packet including a header portion and a trailer portion, and changes the destination of the packet to the transmitting terminal device, Send the data lost packet back to the transmitting terminal. Sender terminal 40
0 receives this and determines that the data portion of the packet has been discarded without receiving an ACK from the receiving terminal side,
Perform retransmission processing. In FIG. 13, the packet of segment 4 is a retransmission of the packet of segment 3. As described above, when the network node device and the terminal device of the present invention are used, A
Since retransmission processing can be performed without being influenced by information such as the value of CK or duplication thereof, the processing time of retransmission can be reduced.

[Embodiment 5] When many communication users simultaneously transmit a large amount of data such as images on a network, the number of packets flowing on the line presses the band of the line, resulting in a congestion state. Sometimes. FIG. 14 shows this. Segments 1, 2, and 3 are transmitting terminal devices a
Thus, segments 1 ′ and 2 ′ are packets transmitted from the transmitting terminal device b, respectively. In the case of this figure, in the dotted frame, at the node of the relay point, when the packets of the segments 1 to 3 coming from the transmitting terminal device a are received,
It is assumed that the packet amount with respect to the bandwidth of the line reaches the limit, and the packets of the segments 1 ′ and 2 ′ coming from the transmitting terminal device b are discarded.

FIGS. 9 and 15 are diagrams for explaining the fifth embodiment of the present invention, and are diagrams showing retransmission of packets using the gateway device according to the present invention and the terminal device according to the present invention. The transmission, relay, and GW in FIG. 15 represent the transmission-side terminal device, the network node device, and the gateway device of the present invention.

In the gateway device 600 shown in FIG. 9, when the data lost packet 613 is received from the network node device, the data lost packet determination function 608 confirms that the packet is a data lost packet. A signal is sent where the number of lost data packets is counted and compared to a reference value. When the count value exceeds the reference value, a write control signal 621 is sent from the data lost packet count comparing function 607 to the transmission data temporary holding function 606, and a transmission stop control signal 622 is sent to the input switch 605. Thereafter, when the frequency of the data lost packet becomes low, the transmission data written in the transmission data temporary holding function 606 is read and transmitted to the receiving side 612 via the input switch 605.

In the network of FIG. 15, congestion occurs on the line in the direction from the network node device at the relay point to the receiving terminal device in the figure, and data sent from the transmitting terminal device presses the line. There is fear. Within the dotted frame, it is assumed that the packet amount with respect to the bandwidth of the line has reached the limit due to the packets of the segments 1, 2, and 3 transmitted from a certain transmitting terminal device a. In this case, the packet of segment 1 'sent from another transmitting terminal device b is discarded by the network node device, and the lost data packet is sent back to the transmitting terminal device b. At this time, the gateway device GW determines that congestion has occurred on the network from the returned packet, and performs subsequent processing of transmitting the packet from the transmitting terminal device b to the receiving side until the congestion stops. Stop temporarily. That is, the packets of the segment numbers 2 ', 3',... In the figure are temporarily stopped on the gateway device.

In this case, the network between the transmitting terminal device b and the gateway device GW is connected to the transmitting terminal device b.
If a different network is used between the network and the network node device and between the gateway device GW and the network node device, the gateway device GW becomes a connection point between the two networks, and the network on the side of the congested network node device And the network on the transmission side terminal apparatus b side without congestion.
With this configuration, the packet transmitted from the transmitting terminal device b can be held in the gateway device GW, and can be transmitted to the network node device after the congestion is resolved. As a result, it is possible to prevent the congestion of the line from being spurred, to prevent the packet from being discarded, and to eliminate the need for repeated retransmission.

[0037]

As described above, according to the present invention,
Since the receiving terminal directly knows that the packet has been discarded by the network node device and can immediately notify the transmitting terminal, the transmitting terminal must retransmit within a short time. Will be able to Further, according to the gateway device of the present invention, it is possible to prevent a further load on the network in the congested state, to achieve early elimination of the congested state, and to prevent packet discarding. In addition, it is possible to reduce the retransmission processing amount of the transmitting terminal device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating packet transmission on a network when a timeout is used as a trigger for packet retransmission.

FIG. 2 shows duplicate A as a trigger for packet retransmission
FIG. 4 is a diagram illustrating packet transmission on a network when CK reception is used.

FIG. 3 is a diagram showing a configuration of a packet.

FIG. 4 is a diagram showing a configuration example of a network node device of the present invention.

FIG. 5 is a diagram showing another configuration example of the network node device of the present invention.

FIG. 6 is a diagram illustrating a configuration example of a transmission terminal function of the terminal device of the present invention.

FIG. 7 is a diagram illustrating another configuration example of the transmission terminal function of the terminal device of the present invention.

FIG. 8 is a diagram showing a configuration example of a receiving terminal function of the terminal device of the present invention.

FIG. 9 is a diagram showing a configuration example of a gateway device of the present invention.

FIG. 10 is a diagram showing a procedure for retransmitting a packet according to the first embodiment of the present invention.

FIG. 11 is a diagram showing a procedure for retransmitting a packet according to the second embodiment of the present invention.

FIG. 12 is a diagram showing a procedure for retransmitting a packet according to a third embodiment of the present invention.

FIG. 13 is a diagram showing a procedure for retransmitting a packet according to a fourth embodiment of the present invention.

FIG. 14 is a diagram illustrating a congestion state of a line.

FIG. 15 is a diagram illustrating functions of a gateway device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 100, 200 Network node device 101, 201 Reception function 102, 202, 204 Transmission function 103, 203 Packet configuration analysis individual part specifying function 104 Input changeover switch 105, 205 Data lost packet configuration function 106, 206 Abnormality control function 111, 211, 217 Transmission side 112, 212 Reception side 113, 114, 213, 214 Packet 115, 215, 216 Data lost packet 121, 221 Packet abnormal signal 122, 123, 222, 223 Control signal 207 Address exchange function 300, 400 Transmission terminal of terminal device Function 301, 401 Transmission data generation function 302, 402 Transmission function 303, 403 Reception function 304, 404 Input / output changeover switch 305, 405 Transmission data temporary holding function 306 Retransmission request determination unit 311 411 Transmission data 312 412 Reception side 313 314 Retransmission request packet 321 421 Read control signal 322 422 Retained data transmission switching control signal 406 Data lost packet determination function 413 414 Data lost packet 500 Reception terminal function 501 Reception function 502 Transmission function 503 Packet configuration analysis section identification function 504 Data lost packet determination function 505 Received data processing function 506 Retransmission request function 511, 515 Transmission side 512 packet 513 Abnormal packet 514 Retransmission request packet 521 Confirmation signal 600 Gateway device 601, 603 Reception function 602 Transmission function 604 Packet configuration analysis specific function 605 Input selector switch 606 Transmission data temporary holding function 607 Data lost packet count Compare function 608 data lost packet determining function 611 receiving side 613 transmission 612 data lost packet 621 write control signal 622 transmission stop control signal

Claims (6)

[Claims] 1. A function for analyzing information of a header portion of a packet arriving from a transmission terminal side to specify a header portion, a data portion, and a trailer portion of a packet. A network node device comprising a function of configuring a data lost packet and a function of transmitting a data lost packet to a receiving terminal. 2. A function of analyzing information of a header portion of a packet arriving from a transmitting terminal to specify a header portion, a data portion, and a trailer portion of the packet. It has a function of composing a data lost packet, and a function of exchanging a destination address and a source address of a header part of the data lost packet to change the destination to the transmitting terminal, and sending the data lost packet back to the transmitting terminal side. A network node device. 3. A function for specifying a header portion, a data portion, and a trailer portion of a packet received from a network, comparing the original size of the packet with the size of the received packet, and determining whether the received packet has data lacking the data portion. A terminal device comprising: a function of discriminating a lost packet when the packet is a lost packet; and a function of returning information of discarding a data part of a packet to a transmitting terminal using an acknowledgment number field of a header part. 4. The terminal device according to claim 3, further comprising a function of, when receiving information of discarding a data portion of a packet from a receiving terminal side, performing a retransmission process of the packet with the highest priority. Characteristic terminal device. 5. The terminal device according to claim 3, further comprising a function of, when a data lost packet is sent back, discriminating the data lost packet and performing a retransmission process of the packet with the highest priority. Characteristic terminal device. 6. When the number of data lost packets, which is located between a terminal device and a network node device and is returned from the network node device to the transmitting terminal, exceeds a predetermined number, transmission from the transmitting terminal is performed. A gateway device having a function of stopping transmission of a received packet to a receiving terminal for a predetermined time.