JPS60106250A - Data communication system - Google Patents

Abstract

PURPOSE:To prevent the congestion of a network by using a controller with a means which delays re-sending operation by a specified time when a reception state confirmation signal shows that reception is disabled. CONSTITUTION:A packet arriving from a terminal 101 is stored in a buffer 102 temporarily. A transmitter 103 outputs it. A packet receiving station 110 receives a packet address to the station among packets sent through the network 107 and outputs it to a terminal 113. The station 110 returns the reception confirmation signal for the packet to the network 107 immediately. A transmitting station receives the reception confirmation signal by a receiver 104 and outpus a signal indicating whether reception confirmation is performed or not to a conrroller 105. The controller 105 when receiving a signal showing the success of the reception erases this packet. On the other hand, when a signal showing the failure in the reception is received, a resent signal is outputted to the transmitter 103 after the specified delay time and the packet stored in the buffer 102 is sent out again to the network 107.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data communication device in a packet communication network that includes flow control means for controlling buffer overflow.

In a packet communication network, it is necessary to avoid packet loss due to overflow of a buffer placed in each communication node. Normally, when the packet arrives, the receiving station of each packet determines whether it can be stored in the reception buffer and sends this status back to the transmitting station, and if the transmitting station returns an unreceivable status. In this case, consider a method such as retransmitting the packet. In this case, if the reception (i-buffer continues to be full), retransmission may be repeated many times and the number of tries in the network will increase, which may lead to a deterioration in the Ii:reachability.Especially when one medium In a network that is accessed, it interferes with communication of other stations.

An object of the present invention is to provide a data communication device that can prevent network congestion as described above.

According to the present invention, in data communication equipment ° that performs packet communication in the form of packet communication in which the reception status of information addressed to the own station received at a receiving station is returned to all transmitting stations, a transmission buffer temporarily stores packets received from outside 8+1. , a transmitting device that connects to the transmitting buffer and sends out packets, packets, and reception status confirmation signals in a form that is compatible with the network, and a transmission device that transmits packets from the own station 3iiC that have come from the network, reception status Ig, and confirmation signals that are returned. If reception at the other station is confirmed by the reception device and reception status confirmation signal, a deletion signal is output to delete the packet from the transmission buffer, and if reception is not confirmed, the specified In a data communication device that performs packet communication in which the reception status is returned to the transmitting station via the transmission device after a time delay, all the packets in the transmission buffer are sent, the transmission buffer temporarily stores packets received from the outside, and the transmission buffer and connection to the retransmission buffer. 17 A transmitting device that sends out packets and reception status confirmation signals in a form that is compatible with the network, and temporarily stores and retransmits transmitted packets and packets that have the same destination as the packet. a buffer, and a receiver that receives packets addressed to the local station from the network and the reception status confirmation signal sent back (M device; Outputs a deletion signal to delete the packet, and if reception is not acknowledged by 611, stores the packet in the self-speed buffer and after a specified time delay () ■ The packet in the sending buffer is sent via the sending device According to the present invention, the data communication device is composed of a control device that outputs a retransmitted water signal for retransmission, and a control device that outputs a retransmission signal for retransmission. In a data communication device that performs packet communication in which the reception status of a packet is returned to a transmitting station, a plurality of transmission buffers temporarily store packets received from the outside for each destination route, and a plurality of transmission buffers described above. A buffer management circuit is connected to the buffer management circuit that manages the timing of transmitting packets from each transmission buffer, and a transmission buffer tC is connected to the packet.

a transmitting device that transmits packets and reception status confirmation signals in a form that is compatible with the network, and a reception device that receives packets addressed to the local station that have arrived from the network and reception status confirmation signals sent back;
If reception (& is confirmed at the other station by the reception status confirmation signal), the relevant packet is deleted from the corresponding transmission buffer. (If the reception is not confirmed after outputting N, the packet is deleted after a specified time delay.) and a control device that outputs a retransmission request signal to a buffer management circuit for retransmitting the packet in the transmission buffer via the transmitting device.

In the present invention, the receiving device receives a reception status confirmation signal for the packet sent from the transmitting device at the packet transmitting station, and if this signal indicates that the packet cannot be received, retransmission is performed for an appropriate time depending on the network situation. Network congestion is avoided by using a control device with delay means. In this case, as a method for generating a retransmission delay, if the operation of the network is steady and its characteristics are known, a pre-calculated constant value is used. One way to adapt to network congestion is to use the number of retransmissions. In other words, an effective method is to determine that an increase in retransmissions is an increase in network congestion and to increase the delay interval. Furthermore, as a means to prevent synchronization of retransmissions from multiple stations, there is a method of specifying a delay time using a random number. Another problem when packets are concentrated at one receiving station is that packets destined for the same receiving station accumulate at each transmitting station, interfering with the transmission of packets destined for other stations. To deal with this, separate sender (I/F) and retransmit buffers are prepared, and only packets to be retransmitted and packets destined for the same route are stored in the retransmit buffer.
It is effective to store other packets in a transmission buffer so that they can be sent to the network even during the delay time for retransmission, or to use a similar means with a buffer on the same route.

The present invention will be described in detail below using one drawing.

FIG. 1 is a block diagram showing a first embodiment of the present invention. , in FIG. 1, a packet coming in from terminal 101 is stored in buffer 102. /shi.

The data was stored in the file 102. Did the packet arrive? p＞
The signals are sequentially output according to instructions from the MCi VC transmitter il 103. ;< (In the K device 103, the network 107
According to the sending output formula, the signal enters from the node 7 faa 102 and outputs the 7 kerato. At the Nonoket receiving station 110, the packet sent via the network 107 is sent to the receiving device 1.
11 receives a message addressed to the receiving station, and outputs it to a terminal 113. When a packet is sent to the receiving station from many stations in succession, the processing for those packets at the receiving station is delayed (by 1 hour).
Even if the packet is addressed to the local station, it cannot be received 75
; In such a case, as a means to prevent the loss of keratin, the delivery value of the packet is immediately returned from the pot 114 to the net 107. At the transmitting station V, the receiving device N+04 receives the reception confirmation signal and sends a signal indicating whether the reception confirmation is correct or not to the control device 105.
Apply to. When the control unit (ii105) receives a signal indicating a successful reception, it outputs a deletion signal to the buffer 102 and deletes the packet, and when it receives a signal indicating a reception failure, it outputs a deletion signal to the buffer 102 and deletes the packet. After a time delay determined within the control device to avoid unnecessary repetition, a retransmission signal is output to the transmitting device 103, and the packet stored in the buffer 102 is sent again to the network 107. Operation (・Packet communication including flow control is possible. Here, the transmitting station and receiving station are explained as separate units, but each station usually has all the functions of transmitting and receiving. In other words, In FIG. 1, even in the first transmission, the receiving device 104 has means for receiving a packet addressed to its own station and outputting it to the terminal 107, and means for notifying the transmitting device of the reception status and outputting a confirmation value if received. Here, an example of the configuration of the network 107 will be explained.Network 1
In 07, each station is sequentially connected in a loop through a unidirectional transmission path, and each station has the function of relaying the input signal to the next station or removing it at that station, so that packets are transmitted sequentially. network configuration is possible. Each station on the network outputs an information packet having the format shown in FIG. 2 or a signal called a token having the 1' format shown in FIG. The token exists uniquely in the network and rotates sequentially between stations. The station receiving the token assumes the right to send out the information packet. The information packets are sequentially relayed from the originating station and returned to the originating station, where they are removed from the network. In the format shown in Figures 2 and 3, each block consists of a number of bits and a bit string of 5 or more, and is used to detect the start of an SD packet.
The type of the ACKit packet indicates whether it is a token or an information packet, and is used for transmission control. 1) A and 5AIa each contain the destination and source addresses. Therefore, the receiving station of the packet can receive the packet addressed to itself by detecting l',:DA. Further, INF is the information part of the packet, POS is a bit string generated from the above-mentioned bit strings, and is used to determine whether there is a bit error in the packet, and HD is used to identify the end of the packet. In the transmission system described here, the bits and bits are changed at the destination receiving station depending on whether the reception status is correct and sent to the network, and the sending station can use this as a reception confirmation signal.

Next, using FIGS. 6, 7, and 8, the control device 105
A more detailed example will be shown. FIG. 6 is a diagram showing a first embodiment of the control device. In the figure, terminal 401
A receiving device is connected to the receiving device, and a reception status confirmation signal is inputted to the judgment circuit 402 .

The determination circuit determines whether the reception is correct or not, and in the case of success, outputs a deletion signal of the terminals 405 Hepa and Fa, and in the case of failure, activates the delay circuit 403. In the delay circuit 403, the terminal 40 is delayed by a predetermined time.
A retransmission request signal is output to 6.

FIG. 7 shows a second embodiment of the control device.

This is a diagram. In the figure, a receiving device is connected to a terminal 501, and a reception status confirmation signal is input thereto, and is input to a judgment circuit 502. The determination circuit determines whether the reception is correct or not, and in the case of success, outputs a deletion signal of the terminals 505 Hepa and Fa, and in the case of failure, the delay time designation circuit 503 and the delay circuit 504
is started. The delay time designation circuit 503 counts the number of failures of the packet, specifies the delay time according to the number of failures, and outputs the result to the delay circuit 504.The delay circuit 504 uses a counter to count the number of failures of the packet. , and then outputs a retransmission request signal to terminal 506. The delay time can be set according to the number of failures using the above-mentioned means.

FIG. 8 shows a third embodiment of the control device.

This is a diagram. In the figure, a terminal 601 is connected to a receiving device, and a reception status confirmation signal is inputted to a judgment circuit 602. The judgment circuit judges whether the reception is correct or not, and in case of success, outputs a buffer deletion signal to terminal 605, and in case of failure, activates counter 603 and pseudo-random number generator 605. Pseudo-random number generator 607 generates a new pseudo-random number, which is compared with the output of counter 603 in comparator circuit 604. When the results match, terminal 6 is
A retransmission request signal is output at 06. The delay time can be specified randomly using the above method.

FIG. 4 is a diagram showing a second embodiment of the present invention. In VC of FIG. 4, a packet received from terminal 201 is stored in buffer 202 for one hour. Ba.

The packets stored in the buffer 202 are sequentially outputted to the transmitting device according to instructions from the transmitter 203 in the order in which they arrive, and are simultaneously stored in the retransmission buffer 208 and released from the buffer 202. The transmitting device 203 outputs the packets received from the buffer 202 using a sending method to the network 207. Approximately 207 has the same function as the network 107 in FIG. 1, receives the 46th issue of the first magazine received by the receiving device [204, and outputs a signal indicating whether the reception confirmation is correct or not to the control device 205.

When the control device 205 receives a signal indicating successful reception, it outputs a deletion signal to the retransmission buffer 208,
4N, which deletes the relevant backt and indicates reception failure.
When the signal is received, the retransmission signal is output to the transmitting device 203 after a time delay determined within the control device in order to avoid unnecessary repetition of reception failures, and the packet network 207 stores the signal in the retransmission buffer 208. Send to. When such a configuration is used, the transmitting device 20 during the delay time for retransmission
3, new packets in the buffer 202 can be sent, but packets destined for the same route are not sent from the transmitting device and are output only to the retransmission buffer. With the above-described operations, communication of packets including Fμ-control becomes possible.

FIG. 5 is a block diagram showing a third embodiment of the present invention. In FIG. 5, terminal 301, terminal 311, terminal 321
Then, packets with different destinations come in and are temporarily stored in buffers 302, 312, and 322, respectively. When a packet is stored in each buffer, a signal indicating the arrival of the packet is output to the buffer management circuit 309. The buffer management circuit 309 determines packets to be output based on instructions from the control device 305 and the order of arrival, which will be described later, and outputs notification signals to each buffer. Each buffer outputs a packet to the transmitter 303 according to instructions from the buffer management circuit 309. The transmitting device 303 outputs the packets received from each buffer according to the sending method to the network 307. The network 307 is the network 10 in FIG.
7, the receiving device 304 receives a reception confirmation signal and sends a signal indicating whether the reception confirmation is correct or not to the control device 3.
Output to 05. When the control device 305 receives a signal indicating a successful reception, it outputs a deletion signal to each buffer and deletes the packet, and when a signal indicating a reception failure is received, it outputs a deletion signal to each buffer, and when a signal indicating a reception failure is received, it deletes the reception failure. After a time delay determined within the control device to avoid repetition, a retransmission signal is output to the buffer management circuit 309, and the packets stored in each buffer are sent out to the network 307 again.

, packet communication including flow control becomes possible with improved operation.

As described above, the present invention not only provides a transmitting/receiving station for realizing network organization that avoids network congestion, but also can be used as a means to avoid buffer overflow in devices connecting networks. It provides a data communication cover with a wide range of applications.

[Brief explanation of drawings]

Figure 1 is a professional diagram showing the first embodiment of the present invention;
3 and 3 are diagrams showing packet formats in an embodiment of a network applied to the present invention, FIG. 4 is a diagram showing a second embodiment of the present invention, and FIG. FIG. 6 is a diagram showing the first embodiment of the control device of the present invention, and FIG. 7 is a diagram showing the second embodiment of the control device of the present invention. FIG. 8 is a block diagram showing a third embodiment of the control device of the present invention. In the figure, 102, 202, 302, 312, 322
is a buffer, 103, 203, 303, 114 is a transmitting device, 104, 204, 304, 111 is a receiving device, 10
5,205° 305 is a control device, 107,207,30
7 is a network, 110 company receiving stations, 208 is a retransmission buffer, 30
9 is a buffer management circuit, 402, 502, 602 is a judgment circuit, 403, 504 is a delay circuit, 503 is a delay time designation circuit, 603 is a counter, 604 is a comparison circuit, 607
indicate pseudorandom number generators, respectively. Arm 7 Figure θ Figure

Claims (1)

[Claims] ] In a data communication device that performs packet communication in which the reception status of information addressed to the own station received at a receiving station is returned to a transmitting station, there is provided a transmission buffer that temporarily stores packets received from the outside. , a transmitting device that connects to the transmitting buffer and sends out packets and reception status confirmation signals in a format compatible with the network, and a reception device that receives packets addressed to the local station that have arrived from the network and reception status confirmation signals that are returned. If reception at the other station is confirmed by the reception status confirmation signal, a deletion signal is output to delete the packet from the transmission buffer, and if reception is not confirmed, the transmission buffer is deleted after a specified time delay. A data communication device comprising: a control device that outputs a retransmission request signal for retransmitting the packet through a transmitting device. 2. In a data communication device that performs packet communication in which the reception status of information addressed to the own station received at the receiving station is returned to the transmitting station, there is a transmitting buffer that temporarily stores packets received from the outside, and a transmitting buffer and retransmission buffer. A transmitter connects to a buffer and sends out packets and reception status confirmation signals in a format compatible with the network; a retransmission buffer temporarily stores transmitted packets and packets with the same destination as the packet; The receiving device receives the incoming packet addressed to its own station and the returned reception status confirmation signal, and if reception at the other station is recorded in the reception status confirmation value number 2, it deletes the packet from the transmission buffer. Delete (if the M number is output and 5Kt= is not received, the packet is stored in the retransmission buffer, and after the specified time delay, the packet with the completion of the portrait buffer is sent.) It is retransmitted via the 4f device. 1. A data communication device characterized by comprising a control device that outputs a retransmission request signal for transmission. a plurality of transmission buffers that temporarily store packets received from the outside for each destination wI using iN by a data communication device that performs packet communication 4M;
Connect to the above multiple sending nodes 1. A communication buffer management line that manages the timing of sending N+ packets from each transmission buffer, and a transmitting device that connects to all transmission buffers and sends packets and reception status confirmation signals in a form suitable for the network. , a receiving device that receives a packet addressed to its own station that has arrived from the network and a received reception status confirmation signal that has been sent back;
Outputs a deletion signal to perform deletion 17 If reception is not confirmed, sends a retransmission signal to the buffer management circuit to retransmit the relevant packet of the transmission request after a specified time delay. A data communication device comprising: a ¥ffl control device that outputs ¥ffl.