JPH11284657A - Retransmission control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress packet retransmission of a communication of low priority in the congestion. SOLUTION: A recording managing means 13 manages the frequency of retransmission showing how many times retransmission is allowed, packet by packet. When a header managing means 14 inquires transmission permission of the recording managing means 13, the managing means 13 decreases the remaining retransmission frequency of a packet by one and allows the transmission on condition that the remaining retransmission frequency of the packet whose transmission permission is requested is >=1. Then the remaining retransmission frequency is 0, the recording managing means 13 instructs a connection control means 12 to stop a communication and the connection control means 12 stops the communication of application 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retransmission control system in connection establishment type communication between communication terminals such as computers.

[0002]

2. Description of the Related Art In conventional connection establishment type communication, when the amount of packets flowing into a node in a network exceeds the capacity of a relay frame holding buffer of the node, excess packets are discarded. Upon receiving the packet, the receiving terminal transmits a response to the packet to the transmitting terminal. If the transmitting terminal does not receive a response within a certain period of time after transmitting the packet, it determines that the transmitted packet has been discarded by the node in the network as described above, and transmits the discarded packet again.

[0003]

However, in the above configuration, when re-transmitting a discarded packet, there is no distinction regarding the priority of the connection, so that packets of all connections are re-transmitted in the same manner. Therefore, FIG.
As in the case of 0, all packets from each transmitting terminal 41 flow into the network congestion point (network node 42) again, so that the network congestion state cannot be resolved and important communication can be performed. There was a problem that it was not possible. The present invention has been made in order to solve the above-described problems, and by providing a transmitting terminal with information for identifying the priority of a connection, packet retransmission of low-priority communication during congestion can be suppressed. It is an object of the present invention to provide a retransmission control method capable of securing the transmission capacity of a network for important and high-speed communication.

[0004]

According to the present invention, as described in claim 1, the transmitting terminal (1) has a maximum allowable retransmission which is preset for each packet according to the priority of communication. Hold the maximum number of retransmissions indicating the number of times, identify the communication priority when establishing a connection, output the maximum number of retransmissions according to the priority, and stop the communication of the application (11) when receiving the instruction to stop the communication. Connection control means (12) for holding the packet to be transmitted received from the application, header management means (14) for requesting transmission permission based on the information specifying the packet, and maximum retransmission received from the connection control means. The remaining number of retransmissions based on the number of times is managed for each packet. If the number of remaining retransmissions of the packet for which transmission permission is requested by the header management means is 1 or more, the packet is And a record management means (13) for instructing the connection control means to stop communication if the remaining number of retransmissions is reduced by one and the header management means is permitted to transmit, and the remaining retransmission number is zero. is there. As described above, the remaining number of retransmissions indicating the number of times retransmission is permitted is managed by the storage management means for each packet. At this time, for the communication having the highest priority, the maximum number of retransmissions is not set, and thus the remaining number of retransmissions is not set. Also, the lower the priority of the communication, the smaller the maximum number of retransmissions, and thus the number of remaining retransmissions. When the header management unit receives a transmission permission inquiry from the header management unit, if the remaining number of retransmissions of the packet for which transmission permission has been requested is one or more, the record management unit reduces the remaining number of retransmissions of the packet by one and reduces the header management unit. Transmission (retransmission) is permitted. Such retransmission is repeated unless a response is received from the receiving terminal.
If the remaining number of retransmissions of the packet for which transmission permission is requested is 0, the record management unit instructs the connection control unit to stop communication, and the connection control unit stops communication of the application.

According to a second aspect of the present invention, a frame holding unit holds a packet transmitted from a transmitting terminal in a frame receiving unit of a network node (2) connected to the transmitting terminal via a network. Buffer (2
2), a discard detection unit (21) for inspecting a packet discarded in the frame holding buffer and instructing transmission of a discard notice when detecting an identifier, Discard notification means (23) for notifying the sender of the discarded packet of the packet discard.
The connection control means (12a) stops communication of the application when the discard notification is received via the network, and the header management means (14a) stops the communication when the identifier insertion instruction is received. To
Insert an identifier into the header of the transmitted packet,
If the remaining number of retransmissions of the packet for which transmission permission is requested from the header management unit is 1, the record management unit (13a)
It instructs the header management means to insert an identifier.
As described above, the record management unit instructs the header management unit to insert an identifier if the remaining number of retransmissions of the packet for which transmission permission is requested by the header management unit is 1, and the header management unit determines whether the header of the transmission packet is , An identifier indicating the last retransmission is inserted. The discard detection means of the network node instructs transmission of a discard notification when the packet with the inserted identifier is discarded, and the discard notification means notifies the source of the discarded packet of the packet discard. The connection control means stops the communication of the application when receiving the discard notification.

According to a third aspect of the present invention, when the transmission side terminal (1b) receives an instruction to set a timer, time measurement is started, and a connection is made every time the measurement time elapses a predetermined time. Reception-side terminal (3) comprising re-communication management means (15) for instructing the control means to perform traffic inspection, and connected to a network node via a network
A connection control unit (31) for transmitting a response packet to the source of the traffic inspection packet when the traffic inspection packet is received, wherein the connection control unit (12b) of the transmitting side terminal communicates with the application. When the timer is stopped, the re-communication management unit is instructed to set a timer, and when the re-communication management unit receives a traffic inspection instruction, a traffic inspection packet is transmitted to the communication destination of the stopped communication, and a response packet to the inspection packet is transmitted. The communication of the application is resumed when it is received. In this way, the connection control means of the transmitting terminal instructs the re-communication management means to set the timer when the communication of the application is stopped, the re-communication management means starts time measurement, and the measurement time is set to the predetermined time. Each time the time elapses, the traffic control unit instructs the connection control unit to perform a traffic test, and the connection control unit transmits a traffic test packet to the communication destination of the stopped communication. The connection control means of the receiving terminal transmits a response packet when receiving the traffic inspection packet. Then, the connection control means of the transmitting terminal,
Resume application communication when a response packet is received. Further, as described in claim 4, the record management means (13c), when requested by the header management means to permit transmission of a packet for which the number of remaining retransmissions is being managed, the maximum number of retransmissions and the number of remaining retransmissions. If the difference is equal to or greater than a predetermined threshold, reduce the maximum number of retransmissions for the destination of the packet for which transmission permission was requested, and if there is no transmission permission inquiry from the header management means for a certain period of time,
This is to initialize the maximum number of retransmissions for the destination of a packet for which no inquiry has been made.

According to a fifth aspect of the present invention, a maximum number of retransmissions indicating the maximum number of retransmissions, which is set in advance for each connection in accordance with the priority of communication, is provided to the transmitting terminal (1d). Connection control means (12d) for holding the communication, identifying the communication priority when establishing the connection, outputting the maximum number of retransmissions according to the priority, and stopping the communication of the application when receiving the instruction to stop the communication; Header management means (14) for holding the received packet to be transmitted and requesting transmission permission based on the information specifying the packet, and managing the remaining number of retransmissions based on the maximum number of retransmissions received from the connection control means for each connection. If the remaining number of retransmissions of the connection set for the packet for which transmission permission is requested is 1 or more, the connection If the remaining number of retransmissions is 0, the header management means is allowed to transmit. If the remaining number of retransmissions is 0, the connection control means is instructed to stop communication, and the header management means issues a transmission permission inquiry. A recording management unit (13d) for returning the number of retransmissions of the connection to a maximum value when there is no fixed time. As described above, the remaining number of retransmissions indicating the number of times retransmission is allowed is managed by the storage management means for each connection. When the header management unit inquires of the transmission permission from the header management unit, if the remaining number of retransmissions of the connection set for the packet requested to be transmitted is 1 or more, the record management unit sets the remaining number of retransmissions of the connection to one. At the same time, the transmission is permitted to the header management means. Such retransmission is repeated unless a response is received from the receiving terminal.
Then, when there is no transmission permission inquiry from the header management unit for a certain period of time (when packet retransmission is not performed for a certain period of time), the record management unit returns the remaining number of retransmissions of the connection to the maximum value.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] Next, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram of a communication system according to a first embodiment of the present invention. The communication system according to the present embodiment includes a transmitting terminal 1, a network node 2 connected to the transmitting terminal 1 via a network, and a receiving terminal 3 connected to the network node 2 via a network. Have been.

The transmitting terminal 1 holds the application 11 and the maximum number of retransmissions set in advance for each packet in accordance with the priority of communication, identifies the priority of communication when establishing a connection, and identifies the priority of communication. Output the maximum number of retransmissions according to
1 and a connection control means 12 for stopping the communication, and a remaining retransmission number indicating the number of times retransmission is allowed is managed for each packet. If there is, the remaining number of retransmissions of the packet is reduced by 1 and the transmission is permitted to the header management means. If the number of remaining retransmissions is 0, the record management means 13 instructing the connection control means 12 to stop communication, It has a header management unit 14 for holding a packet to be transmitted received from the application 11 and requesting the record management unit 13 to permit transmission based on the information specifying the packet.

FIGS. 2 and 3 are flow charts for explaining the operation of the connection control means 12, and FIGS.
FIG. 6 is a flowchart for explaining the operation of the record management unit 13, and FIG. 7 is a flowchart for explaining the operation of the header management unit 14.

The operation at the time of establishing a connection will be described with reference to FIGS. In the transmitting terminal 1,
When the application 11 transmits the connection establishment request information (Step 101 in FIG. 2), the connection control unit 12 extracts the type of the application 11 to communicate with and the address of the communication destination from the received connection establishment request information (Step 102).

The connection control means 12 searches its own priority information table 51 as shown in FIG. 8 based on the acquired communication destination address and application type, and determines in advance the communication destination address and application type. The determined maximum number of retransmissions is obtained from the table 51 (step 103).

The connection control means 12 notifies the record management means 13 of connection establishment information including the communication destination address and application type extracted from the connection establishment request information and the maximum number of retransmissions obtained from the table 51 (step 104). ).

When the data of the maximum number of retransmissions corresponding to the communication destination address and the application type is not registered in the priority information table 51, the connection set for transmitting the packet including the communication destination address and the application type is the priority connection. It is. In this case, the connection control unit 12 notifies the connection establishment information including the communication destination address and the application type, and does not notify the maximum number of retransmissions.

The record management means 13 receives the connection establishment information from the connection control means 12 (FIG. 4).
Step 201), the communication destination address, the application type, and the maximum number of retransmissions are extracted from the connection establishment information (step 202), and these are registered in the maximum number of retransmissions table 52 such as that shown in FIG. 9 (steps 203 and 204). ).

When the maximum number of retransmissions is not notified from the connection control means 12, the recording management means 13
Determines Yes in the determination in step 203, that is, determines that the connection set for transmission of the packet including the notified address and type is the priority connection, and does not register the notified information in the maximum retransmission count table 52 ( Step 203).

Next, the operation at the time of packet transmission will be described with reference to FIGS. Application 11
The header management unit 14 that has received the transmission packet from the server (step 301 in FIG. 7) stores the transmission packet in its own buffer (not shown) (step 302), and from this packet, the communication destination address, the application type, and each packet. No. assigned to the sequential No. Is extracted (step 303).

Then, the header management means 14 stores the communication destination address, application type and sequential No. extracted from the transmission packet. Is notified to the record management means 13 (step 304).
Wait for a response from the record management means 13 (step 30)
5).

Next, when the record management means 13 receives the packet inquiry information from the header management means 14 (step 205 in FIG. 4), the communication destination address, the application type and the sequential No. are determined from the packet inquiry information. Are extracted (step 206 in FIG. 5), and the transmission record table 53 such as that shown in FIG. 10 is retrieved based on these (step 207).

When the communication destination address and the application type extracted from the packet inquiry information are not registered in the transmission record table 53, the connection set for transmitting the packet including this address and the type is the priority connection. In this case, the record management means 1
3 judges Yes in Step 208 and notifies the header management unit 14 of the transmission permission information (Step 20).
9).

The header management means 14 includes a record management means 13
(Step 305 in FIG. 7)
306), and sends the packet held in the buffer to the network (step 307).

The communication destination address and the application type extracted from the packet inquiry information are registered in the transmission record table 53, and the sequential number.
Is not registered in the table 53, the record management unit 13 determines No in Steps 208 and 210, and determines the communication destination address, application type, and sequential No. extracted from the packet inquiry information. And the remaining number of retransmissions corresponding to these
(Step 211). That is, the record management unit 13 stores the communication destination address, the application type, and the sequential No. Is registered in the table 53.

At this time, the maximum number of retransmissions table 52 is searched based on the communication destination address and the application type extracted from the packet inquiry information, and the maximum number of retransmissions corresponding to the connection set for the packet transmission including this address and the type. Is obtained, and the value obtained by subtracting 1 from the obtained maximum number of retransmissions is set as the remaining number of retransmissions. And
The record management unit 13 notifies the header management unit 14 of the transmission permission information (Step 209).

The communication destination address, application type and sequential No. extracted from the packet inquiry information. Is registered in the transmission record table 53,
The record management unit 13 stores the address, type, and No. It is determined whether the number of remaining retransmissions registered in the table 53 is equal to or greater than 1 (step 212). When the number of remaining retransmissions is 1 or more, the record management unit 13 reduces the number of remaining retransmissions registered in the table 53 by 1 (step 213), and notifies the header management unit 14 of transmission permission information (step 209). .

In step 212, the remaining number of retransmissions is 0
In the case of, the record management means 13
o. And the remaining number of retransmissions corresponding to the value 0 are deleted from the transmission record table 53 (step 214). continue,
The record management unit 13 notifies the header management unit 14 of the transmission stop information (step 215), and notifies the connection control unit 12 of the communication stop information including the communication destination address and the application type (step 21).
6).

Next, the operation when communication is stopped will be described with reference to FIGS. Upon receiving the transmission suspension information from the record management unit 13, the header management unit 14 determines No in step 306, and discards the transmission waiting packet held in the buffer (step 308).

The connection control means 12 receives the communication stop information from the record management means 13 (step 1 in FIG. 2).
06), the communication destination address and the application type are extracted from the communication stop information (Step 107 in FIG. 3), and the communication of the corresponding connection of the application 11 is stopped (Step 108).

Next, the operation when a response to the transmission packet is received from the network will be described with reference to FIGS. A transmission packet from the transmitting terminal 1 is transmitted to the receiving terminal 3 via the network node 2. Upon receiving the packet via the network, the receiving terminal 3 responds to the packet with an ACK (Acknow
ledge). This response ACK is also transmitted to the transmitting terminal 1 via the network node 2.

When the connection control means 12 receives the response ACK from the receiving terminal 3 via the network (step 105 in FIG. 2), the connection control means 12 receives the communication destination address, application type and sequential N from the response ACK.
o. (Step 109 in FIG. 3), and the extracted communication destination address, application type, and sequential N
o. Is notified to the record management means 13 (step 110).

The record management means 13 receives the response reception information from the connection control means 12 (step 2 in FIG. 4).
17), the communication destination address, the application type, and the sequential No. from the response reception information. Is extracted (step 218 in FIG. 6), and the sequential No. And the number of remaining retransmissions corresponding to this are deleted from its own transmission record table 53 (step 219).

Next, the operation when the connection is disconnected will be described with reference to FIGS. Upon receiving the connection disconnection / termination request information from the application 11, the connection control means 12 (step 11 in FIG. 2)
1), the communication destination address and the application type are extracted from the connection disconnection / termination request information (step 112 in FIG. 3), and the disconnection information including the extracted communication destination address and the application type is notified to the record management unit 13 (step 112). 113).

Upon receiving the connection disconnection information from the connection control unit 12 (step 220 in FIG. 4), the record management unit 13 extracts the communication destination address and the application type from the connection disconnection information (step 221 in FIG. 6). Then, all the entries of the connections having the same type are deleted from the transmission record table 53 (step 222).

As described above, the remaining number of retransmissions indicating the number of times retransmission is allowed is managed by the storage management means 13 for each packet. At this time, for the communication having the highest priority, the maximum number of retransmissions is not set, and thus the remaining number of retransmissions is not set. Also, the lower the priority of the communication, the smaller the maximum number of retransmissions, and thus the number of remaining retransmissions. When the header management unit 14 inquires of the transmission permission from the header management unit 14, if the remaining number of retransmissions of the packet for which the transmission permission is requested is 1 or more, the record management unit 13 reduces the remaining number of retransmissions of the packet by 1 and sets the header The transmission to the management means 14 is permitted. As a result, the packet is retransmitted.

Unless a response ACK is received from the receiving terminal 3, the header management unit 14 repeats the inquiry about the transmission permission and repeats the packet retransmission. If the remaining number of retransmissions of the packet for which transmission permission is requested is 0, the record management unit 13 instructs the connection control unit 12 to stop the communication, and the connection control unit 12 stops the communication of the application 11. . In this way, it is possible to suppress packet retransmission of low priority communication.

[Second Embodiment] Next, a second embodiment of the present invention will be described in detail with reference to the drawings. FIG. 11 is a block diagram of a communication system according to a second embodiment of the present invention, and the same components as those in FIG. 1 are denoted by the same reference numerals. The transmitting terminal 1a of the present embodiment includes an application 11, a connection control unit 12a for stopping communication of the application 11 when receiving a discard notification via the network, and a packet for which transmission permission is requested from the header management unit. If the remaining number of retransmissions is 1, the record management unit 13a instructs the header management unit to insert the final identifier, and the header management unit inserts the final identifier into the header of the transmission packet when receiving the instruction to insert the final identifier. Means 14a.

The transmitting terminal 1 is connected via a network.
a discard detecting means 21 for checking a packet discarded in the frame holding buffer 22 and instructing transmission of a discard notice when detecting a final identifier, in a frame receiving unit of the network node 2 connected to the transmitting node a; Frame holding buffer 22 for holding a packet transmitted from 1a
And a discard notifying unit 23 for notifying the source of the packet discarded in the frame holding buffer 22 of the packet discard when receiving the discard notification transmission instruction.

FIG. 12 is a flowchart for explaining the operation of the connection control means 12a, and FIGS.
FIG. 15 is a flowchart for explaining the operation of the record management unit 13a, FIG. 15 is a flowchart for explaining the operation of the header management unit 14a, and FIG.
1 is a flow chart for explaining the operation of FIG. 1, and FIG. 17 is a flow chart for explaining the operation of the discarding notifying means 23, and the same operations as those in FIGS.

The operation of the connection control means 12a when establishing a connection, receiving a response to a transmitted packet, stopping communication, and disconnecting a connection is the same as that of the connection control means 12 of the first embodiment, and The operations at the time of connection establishment, at the time of receiving a response to a transmission packet, and at the time of disconnection are the same as those of the record management unit 13 of the first embodiment.

Next, the operation at the time of packet transmission will be described with reference to FIGS. Header management means 1 receiving a transmission packet from application 11
4a (step 301 in FIG. 15), the packet is stored in its own buffer (not shown) (step 302), and from this packet, the communication destination address, application type, and sequential No. Is extracted (step 303).

Subsequently, the header management means 14a sends the communication destination address, application type and sequential No. extracted from the transmission packet. Is notified to the record management means 13a (step 30).
4) Wait for a response from the record management means 13a (steps 311 and 305).

Next, when the packet management information 13a receives the packet inquiry information from the header management means 14a (step 205 in FIG. 13), the communication destination address, the application type and the sequential No. Are extracted (step 206 in FIG. 14), and the transmission record table 53 such as that shown in FIG. 10 is retrieved based on these (step 207).

When the communication destination address and the application type extracted from the packet inquiry information are not registered in the transmission record table 53, the connection set for the packet transmission including the address and the type is the priority connection. In this case, the record management unit 13
Determines Yes in step 208, and notifies the header management unit 14a of the transmission permission information (step 20).
9).

The header management means 14a is provided with the record management means 1
3a (step 3 in FIG. 15)
05, 306), and sends the packet held in the buffer to the network (step 307).

Further, the communication destination address and the application type extracted from the packet inquiry information are registered in the transmission record table 53, and the sequential No.
Is not registered in the table 53, the record management unit 13 determines No in Steps 208 and 210, and determines the communication destination address, application type, and sequential No. extracted from the packet inquiry information. And the remaining number of retransmissions corresponding to these
(Step 211).

At this time, the maximum number of retransmissions table 52 is searched based on the communication destination address and the application type extracted from the packet inquiry information, and the maximum number of retransmissions corresponding to the connection set for the packet transmission including this address and the type. Is obtained, and the value obtained by subtracting 1 from the obtained maximum number of retransmissions is set as the remaining number of retransmissions. And
The record management unit 13a notifies the header management unit 14a of the transmission permission information (Step 209).

The communication destination address, application type, and sequential No. extracted from the packet inquiry information Is registered in the transmission record table 53,
The record management unit 13 stores the address, type, and No. It is determined whether the number of remaining retransmissions registered in the table 53 is equal to or greater than 1 (step 212). If the number of remaining retransmissions is two or more, the record management unit 13a decreases the number of remaining retransmissions registered in the table 53 by 1 (step 213), and notifies the header management unit 14 of transmission permission information (step 209). .

If the remaining number of retransmissions is 1, the record management means 1
3a determines Yes in Step 231 and notifies the header management unit 14a of the final transmission information (Step 2).
32), the remaining number of retransmissions registered in the transmission record table 53 is reduced by 1 (step 213), and the transmission permission information is notified to the header management means 14 (step 20).
9).

The header management means 14a is provided with the record management means 1
3a (FIG. 15, step 3)
11) Insert the final identifier into the transmission waiting packet held in the buffer (step 312), and upon receiving the transmission permission information, send the packet to the network (step 307).

In step 212, the remaining number of retransmissions is 0
In the case of, the record management means 13a
o. And the remaining number of retransmissions corresponding to the value 0 are deleted from the transmission record table 53 (step 214). continue,
The record management unit 13a notifies the header management unit 14a of the transmission stop information (step 215), and notifies the connection control unit 12a of communication stop information including the communication destination address and the application type (step 216).

Next, the operation of the frame receiving unit of the network node 2 when discarding a packet will be described with reference to FIGS. The discard detection unit 21 determines that a packet discard has occurred in the frame holding buffer 22 because the packet inflow amount has exceeded the capacity (step 4 in FIG. 16).
01), from the discarded packet, the communication source address, communication destination address, application type, sequential No. And a final identifier (step 402).

When the final identifier is detected from the discarded packet (step 403), the discard detection means 21 sends the communication source address, communication destination address, application type and sequential No. to the discard notification means 23. Is notified (step 404).

Upon receiving the discard detection information from the discard detection means 21 (step 405), the discard notification means 23 receives the communication source address, communication destination address, application type and sequential No. from the discard detection information. (Step 406), the communication source terminal is identified based on the communication source address, and the communication destination address, application type, and sequential No. extracted from the discard detection information are sent to the communication source terminal. Is transmitted (step 40).
7).

Next, referring to FIGS. 12 to 17, the packet to which the final identifier is
The operation of the transmitting terminal when discarded in the above will be described. In the transmitting terminal 1a, the connection control means 1
2a receives the discard information from the network (FIG. 1)
2 step 121), the communication destination address, the application type, and the sequential No. Is extracted (step 122), and the communication destination address, application type, and sequential No. are extracted. Is notified to the record management means 13a (step 123), and communication of the application 11 in the corresponding connection is stopped (step 12).
4).

When the record management means 13a receives the connection stop information from the connection control means 12a (step 233 in FIG. 13), the communication destination address, the application type and the sequential No. are obtained from the connection stop information. Is extracted (step 234), and the entry of the packet of the corresponding connection (the extracted sequential No. and the number of remaining retransmissions corresponding thereto) is deleted from the transmission record table 53 (steps 235 and 23).
6).

As described above, the record management means 13a instructs the header management means 14a to insert the final identifier if the remaining number of retransmissions of the packet for which transmission permission has been requested from the header management means 14a is one, and The management means 14a
A final identifier indicating the last retransmission is inserted into the header of the transmission packet.

The discard detection means 21 of the network node 2
Indicates the transmission of a discard notification when the packet in which the final identifier is inserted is discarded, and the discard notification unit 23 notifies the source of the discarded packet of the packet discard. The connection control unit 12a stops communication of the application 11 when receiving the discard notification. Thus, low-priority communication can be quickly stopped during congestion.

[Third Embodiment] Next, a third embodiment of the present invention will be described in detail with reference to the drawings. FIG. 18 is a block diagram of a communication system according to the third embodiment of the present invention. The same components as those in FIGS. 1 and 11 are denoted by the same reference numerals. Transmission-side terminal 1b of the present embodiment
When the communication of the application 11 is stopped, the timer setting is instructed to the re-communication managing means described later, and when the traffic inspection instruction is received from the re-communication managing means, the traffic inspection packet is transmitted to the communication destination of the stopped communication. The connection control means 12b for transmitting and resuming the communication of the application 11 when receiving the response packet to the inspection packet, the record management means 13, the header management means 14, and the time measurement when receiving the instruction of the timer set. It has a re-communication management means 15 which starts and instructs the connection control means 12b to perform a traffic inspection every time a predetermined time elapses.

A connection control means 31 for transmitting a response packet to the source of the traffic inspection packet when the traffic inspection packet is received by the receiving terminal 3 connected to the network node 2 via the network, And an application 32.

FIGS. 19 and 20 are flow charts for explaining the operation of the connection control means 12b of the transmitting terminal 1b, and FIGS. 21 and 22 are flow charts for explaining the operation of the re-communication management means 15. 23 is a flowchart for explaining the operation of the connection control means 31 of the receiving terminal 3, and the same reference numerals are given to the same operations as in FIGS.

The operations of the connection control means 12b at the time of establishing a connection, receiving a response to a transmission packet, and disconnecting the connection are the same as those of the connection control means 12 of the first embodiment.

Next, FIGS. 4, 5, 7, 19 to 23 will be described.
The operation of the transmitting terminal 1b when communication is stopped will be described with reference to FIG. The header management unit 14 that has received the transmission packet from the application 11 (step 3 in FIG. 7)
01), the transmission packet is stored in its own buffer (step 302), and the communication destination address, application type, and sequential No. assigned to each packet from this packet. Is extracted (step 303).

Then, the header management means 14 stores the communication destination address, application type and sequential No. extracted from the transmission packet. Is notified to the record management means 13 (step 304).
Wait for a response from the record management means 13 (step 30)
5).

Next, when the record management means 13 receives the packet inquiry information from the header management means 14 (step 205 in FIG. 4), the communication destination address, the application type and the sequential No. from the packet inquiry information. Are extracted (step 206 in FIG. 5), and the transmission record table 53 such as that shown in FIG. 10 is retrieved based on these (step 207).

The communication destination address, application type, and sequential No. extracted from the packet inquiry information Is registered in the transmission record table 53, and the address, type, and No. are registered. If the remaining number of retransmissions registered in the table 53 corresponding to the
The above No. And the remaining number of retransmissions corresponding to the value 0 are deleted from the transmission record table 53 (step 21 in FIG. 5).
4).

Subsequently, the record management means 13 notifies the header management means 14 of the transmission stop information (step 2).
15), and notifies the connection control means 12b of communication stop information including the communication destination address and the application type (step 216). Upon receiving the transmission stop information from the record management unit 13 (steps 305 and 306 in FIG. 7), the header management unit 14 discards the transmission waiting packet held in the buffer (step 308).

When receiving the communication stop information from the record management means 13 (step 131 in FIG. 19), the connection control means 12b extracts the communication destination address and the application type from the communication stop information (step 13 in FIG. 20).
2) At the same time, the communication of the corresponding connection of the application 11 is stopped (step 133), and re-communication information including the extracted communication destination address and the application type is notified to the re-communication managing means 15 (step 13).
4).

Upon receiving the re-communication information from the connection control means 12b (step 501 in FIG. 21), the re-communication management means 15 extracts the communication destination address and the application type from the re-communication information (step 50 in FIG. 22).
2). Subsequently, the re-communication management unit 15 registers the extracted communication destination address, application type, and corresponding timer number in the timer management table 54 such as FIG.
A timer (not shown) of the timer number is set, and time measurement is started (step 504).

Next, the operation of the transmitting terminal 1b at the time of traffic inspection will be described with reference to FIGS. When the time measured by the timer elapses a predetermined time (step 505), the re-communication management means 15 searches the timer management table 54 based on the number of the timer that has passed the predetermined time, and determines the corresponding communication destination address and The application type is acquired (Step 506).

Then, the re-communication management means 15 notifies the connection control means 12b of the inspection request information including the obtained communication destination address and the application type (step 507), and sets the timer of the timer number to time. Measurement is restarted (step 50)
8).

The connection control means 12b receives the inspection request information from the re-communication management means 15 (step 1).
35), a communication destination address and an application type are extracted from the inspection request information (step 136), a terminal of the communication destination is identified based on the communication destination address, and a traffic inspection including the application type is transmitted to the communication destination terminal. The packet is transmitted (step 137).

Next, the operation of the receiving terminal 3 at the time of traffic inspection will be described with reference to FIGS. Connection control means 31 in the receiving side terminal 3
Receives the traffic inspection packet from the network (step 601 in FIG. 23), extracts the communication source address and application type from the traffic inspection packet (step 602), and identifies the communication source terminal based on the communication source address. Then, an inspection response packet including the application type is transmitted to the communication source terminal (step 603).

Next, the operation of the transmitting terminal 1b at the time of resuming communication will be described with reference to FIGS. Upon receiving the inspection response packet from the network (step 138 in FIG. 19), the connection control unit 12b extracts the communication destination address and the application type from the inspection response packet (step 139 in FIG. 20). Subsequently, the connection control unit 12b restarts communication of the corresponding connection of the application 11 (step 140), and notifies the re-communication management unit 15 of communication restart information including the extracted communication destination address and the application type (step 140). 141).

Upon receiving the communication restart information from the connection control means 12b (step 509 in FIG. 21), the re-communication managing means 15 extracts the communication destination address and the application type from the communication restart information (step 5 in FIG. 22).
10). Then, the re-communication management means 15 has the timer management table 5 having the extracted communication destination address and application type and the timer number corresponding thereto.
4 (step 511), and the timer of the timer number is stopped (step 512).

As described above, the connection control unit 12b of the transmitting terminal 1b instructs the re-communication management unit 15 to set a timer when the communication of the application 11 is stopped. The re-communication management means 15 starts time measurement when receiving the timer set instruction, and instructs the connection control means 12b to perform a traffic inspection every time the measured time elapses a predetermined time.
Transmits a traffic inspection packet to the communication destination of the stopped communication.

The connection control means 31 of the receiving terminal 3
Sends a response packet when it receives a traffic inspection packet. Then, the connection control means 12b of the transmitting terminal 1b restarts communication of the application 11 when receiving a response packet to the inspection packet. In this way, it is possible to maintain the connection of low-priority communication without disconnecting it.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described in detail with reference to the drawings. FIG. 25 is a block diagram of a communication system according to a fourth embodiment of the present invention. The same components as those in FIGS. 1, 11, and 18 are denoted by the same reference numerals. The transmitting terminal 1c according to the present embodiment, when requested by the application 11, the connection control means 12, and the header management means 14 to permit transmission of a packet for managing the remaining number of retransmissions, sets the maximum number of retransmissions and the number of remaining retransmissions. If the difference in the number of retransmissions is equal to or greater than a predetermined threshold, the maximum number of retransmissions for the destination of the packet for which transmission permission has been requested is reduced, and
When there is no inquiry about transmission permission for a certain period of time, the recording management unit 13c and the header management unit 14 that initialize the maximum number of retransmissions for the destination of the packet for which no inquiry has been made.

FIG. 26, FIG. 27 and FIG.
It is a flowchart figure for demonstrating operation | movement of 3c,
4 to 6 are denoted by the same reference numerals.
The operations of the record management unit 13c when establishing a connection, receiving a response to a transmission packet, and disconnecting the connection are the same as those of the record management unit 13 of the first embodiment.

Next, the operation at the time of packet transmission will be described with reference to FIG. 7 and FIGS. 26 to 28. The header management unit 14 that has received the transmission packet from the application 11 (step 301 in FIG. 7) stores the packet in its own buffer (not shown) (step 302), and from this packet, the communication destination address, application type, and sequential No. . (Step 30)
3).

Then, the header management means 14 communicates with the destination address, application type and sequential No. extracted from the transmission packet. Is notified to the record management means 13c (step 30).
4) Wait for a response from the record management means 13c (step 305).

Next, when receiving the packet inquiry information from the header management means 14 (step 205 in FIG. 26), the record management means 13c uses the packet inquiry information to determine the communication destination address, application type, and sequential number. Is extracted (step 206 in FIG. 27),
Based on these, the transmission record table 53 as shown in FIG. 10 owned by itself is searched (step 207).

When the communication destination address and the application type extracted from the packet inquiry information are not registered in the transmission record table 53, the connection set for transmitting the packet including the address and the type is the priority connection. In this case, the record management means 1
3c determines Yes in Step 208 and notifies the header management unit 14 of the transmission permission information (Step 2).
09).

The header management unit 14 is provided with the record management unit 13.
(Step 305 in FIG. 7)
306), and sends the packet held in the buffer to the network (step 307).

Further, the communication destination address and application type extracted from the packet inquiry information are registered in the transmission record table 53, and the sequential No.
Is not registered in the table 53, the record management unit 13c determines No in Steps 208 and 210, and determines the communication destination address, application type, and sequential No. extracted from the packet inquiry information. And the remaining number of retransmissions corresponding to these
(Step 211).

At this time, the maximum number of retransmissions table 52 is searched based on the communication destination address and the application type extracted from the packet inquiry information, and the maximum number of retransmissions corresponding to the connection set for the packet transmission including this address and the type is retrieved. Is obtained, and the value obtained by subtracting 1 from the obtained maximum number of retransmissions is set as the remaining number of retransmissions. And
The record management unit 13c notifies the header management unit 14 of the transmission permission information (Step 209).

The communication destination address, application type, and sequential No. extracted from the packet inquiry information Is registered in the transmission record table 53,
The record management unit 13c searches the timer management table 55 as shown in FIG. 29 of the record management unit 13c based on the communication destination address (step 241 in FIG. 28).

Then, the record management means 13c determines that the communication destination address extracted from the packet inquiry information is registered in the timer management table 55 (step 24).
2) The corresponding timer number is obtained from the table 55, a timer (not shown) of this timer number is set, and the time measurement is started again (step 243).

If the communication destination address extracted from the packet inquiry information is not registered in the timer management table 55, the recording management means 13c registers the communication destination address and the timer number corresponding to the communication destination address in the timer management table 55. At the same time (step 244), a timer (not shown) of the timer number is set, and time measurement is started (step 245).

Next, the record management means 13c searches its own maximum retransmission count table 52 as shown in FIG. 9 based on the communication destination address and the application type extracted from the packet inquiry information, and finds the corresponding maximum retransmission count. And the address, type and sequential No. extracted from the packet inquiry information. , And retrieves the corresponding remaining retransmission count by searching the transmission record table 53 as shown in FIG.

If the difference between the maximum number of retransmissions and the remaining number of retransmissions is equal to or greater than a predetermined threshold (step 246), the record management means 13c stores the communication destination address registered in the maximum number of retransmissions table 52 The maximum number of retransmissions of the connection (the maximum number of retransmissions registered in the table 52 corresponding to the communication destination address) set for transmission of the included packet is reduced (step 247). At this time, the maximum number of retransmissions is reduced to half of the current number.

Next, the record management means 13c determines the address, type, and No. extracted from the packet inquiry information.
It is determined whether the number of remaining retransmissions registered in the transmission record table 53 is equal to or greater than 1 (step 21 in FIG. 27).
2). If the remaining number of retransmissions is one or more, the record management unit 13
c decreases the number of remaining retransmissions registered in the table 53 by 1 (step 213), and
4 is notified of transmission permission information (step 209).

In step 212, the remaining number of retransmissions is 0
In the case of, the record management means 13c
o. And the remaining number of retransmissions corresponding to the value 0 are deleted from the transmission record table 53 (step 214). continue,
The record management unit 13c notifies the header management unit 14 of the transmission stop information (step 215), and notifies the connection control unit 12 of the communication stop information including the communication destination address and the application type (step 21).
6).

Next, the operation at the time of initializing the maximum number of retransmissions will be described with reference to FIGS. When the time measured by its own timer has passed the predetermined time (step 248 in FIG. 26), the record management unit 13c uses the timer management table 5 based on the number of the timer that has passed the predetermined time.
5 to obtain the corresponding communication destination address (step 249).

Then, the record management means 13c checks all the maximum number of retransmissions registered in the maximum number of retransmissions table 52 corresponding to the obtained communication destination address (all the maximum number of retransmissions set for the transmission of the packet including the communication destination address). Initialize the maximum number of connection retransmissions) (step 25).
0), the communication destination address and the corresponding timer number are deleted from the timer management table 55 (step 251). The initial value of the maximum number of retransmissions registered in the maximum number of retransmissions table 52 is a value registered in the priority information table 51.

As described above, when the header management unit 14 requests transmission permission for a packet whose remaining number of retransmissions is managed, the record management unit 13c determines that the difference between the maximum number of retransmissions and the number of remaining retransmissions is a predetermined value. If the number is equal to or greater than the threshold value, the maximum number of retransmissions for the destination of the packet for which transmission permission has been requested is all reduced. Initialize the maximum number of retransmissions. In this way, the traffic volume of low-priority communication can be dynamically suppressed according to the congestion state of the network.

[Fifth Embodiment] Next, a fifth embodiment of the present invention will be described in detail with reference to the drawings. FIG. 30 is a block diagram of a communication system according to a fifth embodiment of the present invention. The same components as those in FIGS. 1, 11, 18, and 25 are denoted by the same reference numerals. The transmitting terminal 1d according to the present embodiment holds the application 11 and the maximum number of retransmissions set in advance for each connection in accordance with the communication priority, identifies the communication priority when establishing the connection, and identifies the priority. A connection control unit 12d for outputting the maximum number of retransmissions according to the above, and stopping the communication of the application 11 upon receiving a communication stop instruction, and managing the remaining number of retransmissions indicating the number of times retransmission is permitted for each connection,
If the number of remaining retransmissions of the connection set for the packet requested to be transmitted is 1 or more, the number of remaining retransmissions of the connection is reduced by 1 and the header management unit 14
If the remaining number of retransmissions is 0, the connection control unit 12d is instructed to stop communication, and if there is no transmission permission inquiry from the header management unit 14 for a certain period of time, the remaining retransmission of the connection is performed. It has a recording management means 13d for returning the number of times to the maximum value (maximum number of retransmissions-1), and a header management means 14.

FIG. 31 is a flowchart for explaining the operation of the connection control means 12d, and FIGS.
3, FIG. 34 and FIG. 35 are flowcharts for explaining the operation of the recording management means 13d, and the same reference numerals are given to the same operations as those in FIG. 2 to FIG. When receiving a response to the transmission packet in the connection control unit 12d,
The operation when the communication is stopped and when the connection is disconnected is the same as that of the connection control unit 12 of the first embodiment.

Next, the operation at the time of establishing a connection will be described with reference to FIGS. Sender terminal 1
In step d, when the application 11 transmits the connection establishment request information (step 151 in FIG. 31), the connection control unit 12d extracts the type of the application 11 and the address of the communication destination from the received connection establishment request information (step 151). 152).

The connection control means 12d searches its own priority information table 56 as shown in FIG. 36 based on the acquired communication destination address and application type, and determines the communication destination address and application type in advance. The determined maximum connection retransmission count is obtained from the table 56 (step 153).

Then, the connection control means 12d
The connection management information including the communication destination address and application type extracted from the connection establishment request information and the maximum number of connection retransmissions acquired from the table 56 is notified to the record management unit 13d (step 15).
4).

If data of the maximum number of retransmissions corresponding to the communication destination address and the application type is not registered in the priority information table 56, the connection set for the transmission of the packet including this address and the type is the priority connection. . In this case, the connection control unit 12d notifies the connection establishment information including the communication destination address and the application type, and does not notify the connection maximum retransmission count.

Upon receiving the connection establishment information from the connection control unit 12d (step 261 in FIG. 32), the record management unit 13d extracts the communication destination address, the application type, and the maximum number of connection retransmissions from the connection establishment information (step 262). ), And register them in the maximum number of retransmissions table 57 such as that shown in FIG. 37, and also register the corresponding remaining connection retransmission number in the table 57 (steps 263 and 26)
4).

At this time, a value obtained by subtracting 1 from the maximum connection retransmission count is set as the connection remaining retransmission count. If the connection control unit 12d does not notify the maximum number of retransmissions, the record management unit 13d
Determines that the connection set for the transmission of the packet including the notified address and type is a priority connection in the determination of step 263, and does not register the notified information in the maximum retransmission count table 57.

Next, the operation at the time of packet transmission will be described with reference to FIGS. The header management unit 14 that has received the transmission packet from the application 11 (step 301 in FIG. 7) stores the packet in its own buffer (not shown) (step 302), and from this packet, the communication destination address, application type, and sequential No. . (Step 30)
3).

Then, the header management means 14 sends the communication destination address, application type and sequential No. extracted from the transmission packet. Is notified to the record management means 13d (step 30).
4) Wait for a response from the record management means 13d (step 305).

Next, upon receiving the packet inquiry information from the header management means 14 (step 265 in FIG. 32), the recording management means 13d receives the communication destination address, application type and sequential No. from the packet inquiry information. Are extracted (step 266 in FIG. 33), and the transmission record table 58 such as that shown in FIG. 38 is retrieved based on these (step 267).

When the communication destination address and the application type extracted from the packet inquiry information are not registered in the transmission record table 58, the connection set for transmitting the packet including the address and the type is the priority connection. In this case, the record management means 1
3d determines Yes in step 268, and notifies the header management unit 14 of transmission permission information (step 2).
69).

The header management means 14 is
(Step 305 in FIG. 7)
306), and sends the packet held in the buffer to the network (step 307).

The communication destination address and the application type extracted from the packet inquiry information are registered in the transmission record table 58, and the sequential No.
Is not registered in the table 58, the record management unit 13d determines No in Steps 268 and 270, and the sequential No. extracted from the packet inquiry information. Is registered in the transmission record table 58, and the transmission permission information is notified to the header management means 14 (step 269).

The communication destination address, application type, and sequential No. extracted from the packet inquiry information Is registered in the transmission record table 58,
The record management unit 13d searches the timer management table 59 as shown in FIG. 39 owned by itself based on the communication destination address and the application type (step 27 in FIG. 35).
1).

If the communication destination address and the application type extracted from the packet inquiry information are registered in the timer management table 59 (step 272), the record management means 13d acquires the corresponding timer number from the table 59, The timer (not shown) of this timer number is set, and the time measurement is started again (step 273).

If the communication destination address and the application type extracted from the packet inquiry information are not registered in the timer management table 59, the recording management unit 13d sets the communication destination address and the application type and the timer number corresponding thereto. Is registered in the timer management table 59 (step 274), and a timer (not shown) of the timer number is set to start time measurement (step 275).

Next, the record management means 13d determines whether or not the number of remaining connection retransmissions registered in the maximum retransmission number table 57 corresponding to the communication destination address and the application type extracted from the packet inquiry information is 1 or more. (Step 276). When the number of remaining connection retransmissions is 1 or more, the record management unit 13d decreases the number of remaining connection retransmissions registered in the maximum number of retransmissions table 57 by 1 (step 277), and notifies the header management unit 14 of transmission permission information. (Step 26
9).

If the number of remaining connection retransmissions is 0 in step 276, the record management means 13d reads the sequential No. extracted from the packet inquiry information. Is deleted from the transmission record table 58, and the remaining connection retransmission count of the table 57 corresponding to the communication destination address and application type extracted from the packet inquiry information is set to a value obtained by subtracting 1 from the connection maximum retransmission count (step 278).

Subsequently, the record management unit 13d notifies the header management unit 14 of the transmission stop information (step 279), and also notifies the connection control unit 12d of the communication stop information including the communication destination address and the application type (step 279). Step 280).

Next, an operation when a response to a transmission packet is received from the network will be described with reference to FIGS. 3, 31 to 35. When receiving the response ACK from the network (step 105 in FIG. 31), the connection control unit 12d receives the communication destination address, the application type, and the sequential N from the response ACK.
o. (Step 109 in FIG. 3), and the extracted communication destination address, application type, and sequential N
o. Is notified to the record management means 13d (step 110).

When the record management means 13d receives the response reception information from the connection control means 12d (step 281 in FIG. 32), the record management means 13d obtains the communication destination address,
Application type and sequential No. Is extracted (step 282 in FIG. 34), and the sequential No.
Is deleted from the transmission record table 58 (step 28).
3).

Next, the operation at the time of recovery of the number of remaining connection retransmissions will be described with reference to FIGS. When the time measured by the timer of the record management means 13d has passed a predetermined time (step 28 in FIG. 32).
4) The timer management table 59 is searched based on the number of the timer after a predetermined time has elapsed, and the corresponding communication destination address and application type are obtained (step 285 in FIG. 34).

Subsequently, the record management means 13d transmits the remaining connection retransmission count registered in the maximum retransmission count table 57 corresponding to the obtained communication destination address and application type (the transmission of the packet including the communication destination address and the application type). Is returned to the maximum value (remaining number of retransmissions of the connection set for (step 28 in FIG. 34).
6). The maximum value at this time is the maximum retransmission count table 5 corresponding to the communication destination address and the application type.
7 is a value obtained by subtracting 1 from the maximum number of retransmissions registered.

Then, the record management unit 13d deletes the entry of the connection (the communication destination address and the application type and the timer number corresponding thereto) from the timer management table 59 (step 28).
7).

Next, the operation at the time of disconnection will be described with reference to FIGS. Upon receiving the connection disconnection / termination request information from the application 11 (step 111 in FIG. 31), the connection control unit 12d extracts the communication destination address and the application type from the connection disconnection / termination request information (FIG. 3).
(Step 112), and notifies the record management unit 13d of the connection disconnection information including the extracted communication destination address and application type (Step 113).

Upon receiving the connection disconnection information from the connection control unit 12d (step 288 in FIG. 32), the record management unit 13d extracts the communication destination address and the application type from the connection disconnection information (step 289 in FIG. 34). Table of the number of retransmissions for the entry of the connection having the same type and connection
7. Delete all from the transmission record table 58 (step 290).

As described above, the remaining number of retransmissions is managed for each connection by the storage management means 13d. The record management unit 13d, when receiving a transmission permission inquiry from the header management unit 14, if the remaining number of retransmissions of the connection set for the packet for which transmission permission is requested is 1 or more, the remaining number of retransmissions of the connection Is reduced by one, and transmission to the header management means 14 is permitted. Then, when there is no transmission permission inquiry from the header management unit 14 for a certain period of time (when packet retransmission is not performed for a certain period of time), the record management unit 13d returns the remaining number of retransmissions of the connection to the maximum value.

[0123]

According to the present invention, by providing a connection control means, a header management means, and a record management means in a transmitting terminal as described in claim 1, packet retransmission of low priority communication is suppressed. Therefore, it is possible to reduce the traffic usage of low-priority communication at the time of network congestion, and to secure the transmission capacity of the network for high-priority communication.

According to a second aspect of the present invention, a frame holding buffer is provided in the frame receiving unit of the network node.
By providing the discard detection unit and the discard notification unit, it is possible to notify the transmitting terminal that the final retransmission packet of the low-priority communication has been discarded by the network node. Can be stopped promptly.

Further, by providing retransmission management means in the transmitting terminal and providing connection control means in the receiving terminal, packet retransmission of low priority communication can be suppressed. When the congestion state of the network is resolved (when a response packet to the traffic inspection packet is received), the low-priority communication is restarted, so that the connection of the low-priority communication is maintained without disconnection. be able to.

Further, since the record management means controls the maximum number of retransmissions of low-priority packets in accordance with the congestion state of the network, the traffic of low-priority communication is controlled. The amount can be dynamically reduced according to the congestion state of the network.

Further, by providing a connection control means, a header management means and a record management means in the transmitting terminal as described in claim 5, packet retransmission of low priority communication in which packet discarding occurs continuously. Can be suppressed, and the traffic volume of low-priority communication can be reduced more effectively when the network is chronically congested.

[Brief description of the drawings]

FIG. 1 is a block diagram of a communication system according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of connection control means in the transmitting terminal of FIG. 1;

FIG. 3 is a flowchart for explaining the operation of the connection control means in the transmitting terminal of FIG. 1;

FIG. 4 is a flowchart for explaining the operation of a record management unit in the transmitting terminal of FIG. 1;

FIG. 5 is a flowchart for explaining the operation of a record management unit in the transmitting terminal of FIG. 1;

FIG. 6 is a flowchart for explaining the operation of a record management unit in the transmitting terminal of FIG. 1;

FIG. 7 is a flowchart for explaining the operation of the header management means in the transmitting terminal of FIG. 1;

FIG. 8 is a diagram showing a priority information table included in connection control means in the transmitting terminal of FIG. 1;

9 is a diagram showing a maximum number of retransmissions table included in a record management unit in the transmitting terminal of FIG. 1;

FIG. 10 is a diagram showing a transmission record table included in a record management unit in the transmission-side terminal of FIG. 1;

FIG. 11 is a block diagram of a communication system according to a second embodiment of the present invention.

FIG. 12 is a flowchart for explaining the operation of the connection control means in the transmitting terminal of FIG. 11;

FIG. 13 is a flowchart for explaining the operation of the record management means in the transmitting terminal of FIG. 11;

FIG. 14 is a flowchart for explaining the operation of a record management unit in the transmitting terminal of FIG. 11;

FIG. 15 is a flowchart illustrating the operation of a header management unit in the transmitting terminal of FIG. 11;

FIG. 16 is a flowchart illustrating the operation of a discard detection unit in the network node of FIG. 11;

FIG. 17 is a flowchart for explaining the operation of a discard notification unit in the network node of FIG. 11;

FIG. 18 is a block diagram of a communication system according to a third embodiment of the present invention.

FIG. 19 is a flowchart for explaining the operation of the connection control means in the transmitting terminal of FIG. 18;

20 is a flowchart for explaining the operation of the connection control means in the transmitting terminal of FIG. 18;

FIG. 21 is a flowchart for explaining the operation of the re-communication management means in the transmitting terminal of FIG. 18;

FIG. 22 is a flowchart for explaining the operation of the re-communication management means in the transmitting terminal of FIG. 18;

FIG. 23 is a flowchart for explaining the operation of the connection control means in the receiving terminal of FIG. 18;

FIG. 24 is a diagram showing a timer management table included in the re-communication management means in the transmitting terminal of FIG.

FIG. 25 is a block diagram of a communication system according to a fourth embodiment of the present invention.

FIG. 26 is a flowchart for explaining the operation of the record management means in the transmitting terminal of FIG. 25;

FIG. 27 is a flowchart for explaining the operation of the record management means in the transmitting terminal of FIG. 25;

FIG. 28 is a flowchart for explaining the operation of the record management means in the transmitting terminal of FIG. 25;

FIG. 29 is a diagram showing a timer management table included in a record management unit in the transmitting terminal of FIG. 25.

FIG. 30 is a block diagram of a communication system according to a fifth embodiment of the present invention.

FIG. 31 is a flowchart for explaining the operation of the connection control means in the transmitting terminal of FIG. 30;

FIG. 32 is a flowchart illustrating the operation of a record management unit in the transmitting terminal of FIG. 30;

FIG. 33 is a flowchart illustrating the operation of a record management unit in the transmitting terminal of FIG. 30;

FIG. 34 is a flowchart for explaining the operation of the recording management means in the transmitting terminal of FIG. 30;

FIG. 35 is a flowchart for explaining the operation of the record management means in the transmitting terminal of FIG. 30;

36 is a diagram showing a priority information table possessed by connection control means in the transmitting terminal of FIG. 30.

FIG. 37 is a diagram showing a maximum number of retransmissions table held by a record management unit in the transmitting terminal of FIG. 30;

FIG. 38 is a diagram illustrating a transmission record table included in a record management unit in the transmission-side terminal in FIG. 30;

FIG. 39 is a diagram showing a timer management table included in a record management unit in the transmitting terminal of FIG. 30.

FIG. 40 is a diagram for explaining a problem of a conventional communication system.

[Explanation of symbols]

1, 1a, 1b, 1c, 1d: transmitting terminal, 2: network node, 3: receiving terminal, 11, 32: application, 12, 12a, 12b, 12d, 31: connection control means, 13, 13a, 13c , 13d: record management means, 14, 14a: header management means, 15: re-communication management means, 21: discard detection means, 22: frame holding buffer, 23: discard notification means, 51, 56 ... priority information table, 52 , 57... Maximum retransmission count table 5
3, 58: transmission record table, 54, 55, 59: timer management table.

Claims (5)

[Claims] 1. A retransmission control method for a packet in connection-establishment type communication, comprising: a maximum retransmission indicating a maximum number of times retransmission is permitted, which is set in advance for each packet in accordance with a communication priority to a transmitting terminal. Hold the count,
Connection control means for identifying the priority of communication at the time of establishing a connection, outputting the maximum number of retransmissions according to the priority, and stopping communication of the application when an instruction to stop communication is received, and a packet to be transmitted received from the application Header management means for requesting transmission permission based on the information specifying the packet; and managing the remaining number of retransmissions for each packet based on the maximum number of retransmissions received from the connection control means, and permitting transmission permission from the header management means. If the number of remaining retransmissions of the obtained packet is 1 or more, the remaining number of retransmissions of the packet is reduced by 1 and transmission is permitted to the header management means. If the number of remaining retransmissions is 0, communication with the connection control means is performed. And a record management means for instructing to stop the retransmission. 2. The retransmission control system according to claim 1, wherein a frame holding buffer for holding a packet transmitted from the transmitting terminal is provided in a frame receiving unit of a network node connected to the transmitting terminal via a network. Inspect the dropped packets in the frame holding buffer,
Discard detection means for instructing transmission of a discard notification when an identifier is detected, and discard notification means for notifying the source of the packet discarded in the frame holding buffer of the packet discard when receiving the discard notification transmission instruction. The connection control means stops communication of an application when the discard notification is received via a network, and the header management means, upon receiving an identifier insertion instruction, The record management means, if the remaining number of retransmissions of the packet requested to be transmitted by the header management means is 1, instructs the header management means to insert the identifier. Characteristic retransmission control method. 3. The retransmission control method according to claim 1, wherein time measurement is started when the transmitting terminal receives an instruction to set a timer, and each time the measurement time elapses a predetermined time, connection control means. Retransmission management means for instructing a traffic inspection packet to be transmitted to a receiving terminal connected to a network node via a network, and when a traffic inspection packet is received, a response packet is transmitted to a source of the traffic inspection packet. Connection control means, the connection control means of the transmitting terminal instructs the re-communication management means to set a timer when the communication of the application is stopped, and stops when receiving a traffic inspection instruction from the re-communication management means. Sends a traffic inspection packet to the destination of the A retransmission control method for resuming application communication when a response packet is received. 4. The retransmission control method according to claim 1, wherein the record management unit determines the maximum number of retransmissions and the number of remaining packets when the header management unit requests transmission permission for a packet managing the number of remaining retransmissions. If the difference in the number of retransmissions is equal to or greater than a predetermined threshold, reduce the maximum number of retransmissions for the destination of the packet for which transmission permission is requested, and if there is no transmission permission inquiry from the header management unit for a certain period of time,
A retransmission control method for initializing a maximum number of retransmissions for a destination of a packet for which no inquiry has been made. 5. A retransmission control method for a packet in connection-established communication, comprising: a maximum retransmission indicating a maximum number of retransmissions permitted to a transmitting terminal, which is preset for each connection according to a communication priority. A connection control unit that holds the number of times, identifies the communication priority when establishing a connection, outputs the maximum number of retransmissions according to the priority, and stops the communication of the application when the communication stop instruction is received. Header management means for holding a packet to be transmitted and requesting transmission based on information specifying the packet; and managing the remaining number of retransmissions based on the maximum number of retransmissions received from the connection control means for each connection. If the remaining number of retransmissions of the connection set for the packet for which permission is requested is 1 or more The remaining number of retransmissions of the connection is reduced by 1 and transmission is permitted to the header management means. If the remaining number of retransmissions is 0, the connection control means is instructed to stop communication, and the header management means issues a transmission permission inquiry. A retransmission control method comprising: a recording management unit that returns the remaining number of retransmissions of the connection to a maximum value when there is no fixed time.