JPH04192942A - Loop type network communication system - Google Patents

Abstract

PURPOSE:To accelerate a retransmission processing and to prevent a data from being missed by transmitting the data from a transmitting station while adding a read pointer to a packet, and transmitting the data again after adding the read pointer again when the data is returned since it can not be received by a receiving station. CONSTITUTION:In communication defining a communication node device 1 as the transmitting station and defining a communication node device 3 as the receiving station, a real packet RP is transmitted and at such a time, however, the read pointer for reading from a transmission buffer is added by a packet generation part. On the other hand, when the data can not be received at the device 3 by any cause, the packet is not erased but returned to the device 1 in a busy state. The device 1 temporarily erases this packet and based on the read pointer in the returned packet, however, the packet is read out from the transmission buffer again, added at the packet generation part and transmitted again. Thus, the retransmission processing is accelerated, and the data is prevented from being missed.

Description

[Detailed Description of the Invention] [Summary] Regarding a loop-type network communication method in which a monitoring node device and a plurality of communication node devices are connected via a circular transmission path and communication is performed between each communication node device, The aim is to prevent data loss by efficiently retransmitting packets that could not be received.In order to prevent data loss by efficiently retransmitting packets that could not be received, the packet is generated with a read pointer for the data in the packet in the transmitting buffer of the transmitting station in the packet transmitted from the transmitting station. When the receiving station cannot receive the data and returns the data as it is, the transmitting station reads the data in the bucket again from the transmitter based on the read pointer and retransmits it to the receiving station. Configure.

[Industrial application field]

The present invention relates to a loop type network communication system, and more particularly to a loop type 2.2 tow network communication system in which a monitoring node device and a plurality of communication node devices are connected through a circular transmission path, and communication is performed between each communication node device. It is something.

In recent years, with the development of a highly information-oriented society, the importance of the content of each piece of data in data communications has increased.

For this reason, in loop network communication systems such as LAN (Local Area Network), it is necessary to take measures when a packet sent by the local station cannot be received by the other station.

(Prior art) In the conventional loop network communication system, the fourth
The packet format shown in the figure.

data communication between communication node devices is performed using

In FIG. 4, the control unit is an area that controls the entire packet such as the frame synchronization unit and the usage status of the packet, the destination address is the address of the communication node device as a receiving station, and the source address is the communication node device as the originating station. The address and packet attributes indicate whether the packet was received by the communication node device specified by the destination address, the data indicates fJfit of the actual packet data, and the check indicates the validity check area of the packet data. There is.

An example of communication using packets in such a bucket format is shown in FIG. When received by the communication node device 3 as a receiving station designated by the destination address, the packet data is erased by the so-called receiving station erasing method, and the packet attribute is changed from busy state to ready state, and the packet is stored as an EP (bucket). Since the data is sent, the communication node device 1 knows that the reception was performed normally.

On the other hand, as shown in FIG. 3(b), for example, if the reception buffer of the receiving station is full or the terminal connected to the communication notebook device is powered off and cannot receive data, the communication node device 3 Since the actual packet RP whose packet attribute has been rewritten to the busy state is returned to the communication node device 1, the communication node device 1 retransmits the packet to prevent packet reception errors.

[Problem to be solved by the invention]

In such conventional systems, when a packet with a busy packet attribute returns to the originating station, the originating station performs a process of temporarily erasing the data of the packet.

This is because if the returned packet continues to flow through the loop network, the receiving station will no longer know the relationship between that packet and the packets that follow.

Therefore, in order to retransmit the erased packet data, it is necessary to retransmit it, for example, from the beginning of the transmission process, which poses a problem in that the received data processing at the receiving station becomes redundant and wasteful.

Therefore, the present invention provides a loop-type network communication method in which a monitoring node device and a plurality of communication node devices are connected through a circular transmission path and communication is performed between each communication node device, in which the destination receiving station cannot receive the data. The purpose is to prevent data loss by efficiently retransmitting packets that have been sent.

[Means and effects for solving the problem] The loop type network communication system according to the present invention uses a bucket format as shown in FIG. This bucket format is the bucket format shown in FIG. 4 plus a read pointer for the transmission buffer at the originating station, and as shown in FIG. A read pointer for the data in the packet is added by the packet generating unit 14, and when the receiving station cannot receive the data and the packet returns as is, the transmitting station re-enters the data from the transmitting buffer 20 based on the read pointer. It is characterized by reading out the data and retransmitting it to the receiving station.

That is, during normal communication, as shown in FIG. 5(a), in communication where the communication node device 1 is the transmitting station and the communication node device 3 is the receiving station (indicated by the dotted line), the communication node device 1
The actual packet RP (shown by the shaded area) is transmitted from the actual packet RP, and at this time, the packet generator 14 adds a read pointer to the packet when reading from the transmission buffer 20, as shown in FIG.

After this transmission packet is received by the communication node device 3 via the communication node device 2, the packet is erased, becomes an empty packet EP, and is returned to the communication node device 1.

On the other hand, as shown in Q)) of the same figure, even though the real bucket If you are unable to receive it for some reason,
The actual packet RP with the packet attribute rewritten to the busy state is returned to the originating station without erasing the packet.

Then, in the communication node device 1 as a source station, if the source of the received packet is the local station, this packet is temporarily deleted, but as shown in FIG. 2, the read pointer in the returned packet is Based on this, the packet is read out again from the transmission buffer 20, and the packet generation unit 14 generates a packet and retransmits it.

In the second manner, the transmitting station can immediately know the packet data in the transmission frame to be retransmitted using the read pointer, and can accurately retransmit the packet.

〔Example〕

FIG. 3 shows an embodiment of each communication node device used in the loop type network communication system according to the present invention, and in the figure, 10 is a packet analysis unit that analyzes received packets according to their format. , 11 is a reception buffer unit that stores received data, 12 is a packet modification unit that modifies received packets, 13 is a transmission buffer unit that stores transmission data from a terminal, and 14 is a transmission buffer unit 13 that is read out from the transmission buffer unit 13. A packet generating section 15 packetizes data, a transmission control section 15 controls switching of packets to be transmitted, and a switching section 16 sends out transmission data.

In addition, a transmission pamphlet 7 part 13, and a transmission buffer 20 configured of, for example, a RAM (random access memory),
a write control unit 21 that performs write control of the transmission buffer 20;
a read control unit 22 that performs read control of the transmission buffer 20;
It is made up of.

The operation of the above embodiment will be explained below.

During normal operation, when data from a terminal is accumulated in the transmission buffer 20, the write control section 21 sends data to the transmission control section 15.
A write completion signal 25 is notified to the transmission control unit 15, a read permission signal 26 is given to the read control unit 22, data is read out from the transmission buffer 20 according to the read pointer 24, and the packet generation unit 14 reads the data as required. Packet information and a read pointer are added, and the switching unit 16 selects the transmission data in response to the data selection signal 27 from the transmission control unit 15, and transmits it to the downstream communication node device.

Note that the transmission control unit 15 controls the transmission buffer 20 as described above.
If there is data to send from the packet.

The packet analysis unit 10 receives the packet empty signal 31 from the packet analysis unit 10 only when the packet data in the received data is empty or when it is necessary to make the packet data in the received data empty for retransmission or the like, The switching section 16 is switched to the packet generation section 14 side by the data selection signal 27, and the packets from the packet modification section 12 are otherwise selected.

Next, when a packet is received, the packet analysis section 10 analyzes the received packet, and if the destination address is the local station, a write permission signal 28 is given to the reception buffer section 11 to accumulate the received data.

The received packet is erased by the packet modification unit 12 to make it an empty packet based on the analysis result signal 29 from the packet analysis unit 10, and transmission data is selected by the data selection signal 27 from the transmission control unit 15, and the downstream Send to communication node device.

On the other hand, if the received packet cannot be received for some reason as described above, the packet analysis unit 1
Based on the analysis result signal 29 from 0, the packet modification unit 12 does not erase the packet but sets the packet attribute to busy, and the data select signal 27 from the transmission control unit 15 selects the side of the packet modification unit 12. The packet is then sent as transmission data to the downstream communication node device.

If the analysis result of the packet received in this way shows that the source is the local station and the packet attribute is busy, the packet analysis unit 10 determines that this packet is a packet that was not received by the receiving station, The received packet is erased by the packet modification unit 12 and becomes an empty packet.

At this time, the packet analyzer 10 controls the read controller 22 based on the read pointer 30 written in the received packet to read the same data again from the transmit buffer 20, and the packet generator 14 generates a packet.

At the same time, the packet analysis unit 1o notifies the transmission control unit 15 that an empty packet will be generated, so the transmission control unit 15 switches the switching unit 16 to the bucket generation unit 15 side for the period of this packet, and then sends the packet to the transmission control unit 15. is transferred to the downstream communication notebook device.

〔Effect of the invention〕

As explained above, according to the loop-type footwork communication method according to the present invention, a read pointer for the data in the packet in the transmission buffer of the transmitting station is added to the packet transmitted from the transmitting station, so that the packet can be received by the receiving station. When the transmitting station returns without any change, the transmitting station is configured to read the backent data again from the transmitting buffer based on the read pointer and retransmit it to the receiving station, so the transmitting station does not transmit the retransmitted data. Since packets can be retrieved and transmitted accurately and quickly, retransmission processing becomes faster and there is no need for extra packet processing at the receiving station.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a bucket format used in the loop-type network communication method according to the present invention, and FIG. 2 is a basic configuration block diagram of a communication node device used in the loop-type footwork communication method according to the present invention. FIG. 3 is a block diagram showing an embodiment of a communication node device used in the loop type network communication system according to the present invention, FIG. 4 is a diagram showing a conventionally used packet format, and FIG. , is a diagram for explaining packet communication in a loop network. In FIG. 1, 20...transmission buffer, 14...packet generation unit. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a loop-type network communication method in which a monitoring node device and a plurality of communication node devices are connected by a ring transmission path and communication is performed between each communication node device, a transmission buffer (20) of the source station is used for packets transmitted from a source station. The read pointer of the data in the packet in the packet generator (
14), and when the packet is returned without being received by the receiving station, the transmitting station reads the data of the packet again from the transmission buffer (20) based on the read pointer and sends it to the receiving station. A method characterized by retransmission.