JPH11243404A - Autonomous distribution system and transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission system that is able to deal with connection to a general purpose network system represented by a CSMA/CD system or extension of an existing network system and prevent data loss in the middle of transmission. SOLUTION: A function code filtering device 101, which has a buffer for temporarily storing transmission and reception data, a means for detecting that using amount of this buffer exceeds the predetermined normal amount, and a dummy data transmission means for transmitting dummy data on a network when normal amount exceeding the use amount is detected by the buffer, is provided between a host computer 102 of a transmission device and a main trunk network 103. Collision is made to occur between the transmission data and the dummy data, and retransmission of the data is facilitated when the transmission data from other transmission device connected to a transmission line of the main trunk network 103 are transmitted to general-purpose CSMA/CD system networks 104 and 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autonomous decentralized system and a transmission system having a high-performance transmission device for relaying a transmission path and converting a transmission protocol, and more particularly to an autonomous decentralized system in consideration of preventing data loss during transmission. System and transmission system.

[0002]

2. Description of the Related Art CSMA / CD (Carrier Securities) is a network transmission method that allows data collision on a transmission path.
An nse Mutiple Access / Collision Detect) method is generally known. In this method, a transmission device (station) requesting transmission among a plurality of transmission devices connected to a bus checks whether a signal is flowing on a transmission path, and if no signal is flowing, transmits data (telegram). It is characterized in that it is not necessary to be aware of the state of another transmission device and the control is simple.

However, since the speed at which a message propagates through a transmission line is finite, even if the message has already been sent from another transmission device (station), no signal has arrived at its own station. Is determined, and transmission of the message may be started. In this case, since a plurality of messages collide with each other on the transmission path, the message cannot be normally received by the partner station. However, the message is retransmitted by transmission error control and can be relieved. In the CSMA / CD system, when transmission of a message is started, a transmission device that requests transmission monitors whether or not a collision has occurred on a transmission line, and immediately stops transmitting the message if a collision is detected.

[0004] On the other hand, a gateway that supports connection between networks is known as a transmission device for relaying a network or converting a transmission protocol. The gateway enables connection between a plurality of networks of the same type or of different types, and its transmission device includes a high-performance computing device for performing protocol conversion and the like in accordance with the mutual network specifications. However, the amount of data processing in the gateway is limited due to the need for advanced calculations. For this reason, in data transmission via the gateway, there may be restrictions such as suppressing the amount of data transferred at one time.
Without such restrictions, the data processing inside the gateway cannot keep up with the amount of data received from the network,
Omission of data reception may occur. As described above, in a transmission system via a high-performance transmission device such as a conventional gateway, it is necessary to reduce the data transfer capacity in order to avoid the risk of omission of data reception.

[0005]

SUMMARY OF THE INVENTION In the present invention, in network transmission via a high-performance transmission device, CSMA /
It can be connected to a general-purpose network system typified by the CD system or added to an existing network system, preventing data loss during transmission and reducing the load on the host computer that manages the transmission device. It is an object of the present invention to provide an autonomous decentralized system and a transmission system that can perform the same.

[0006]

SUMMARY OF THE INVENTION The present invention provides a computer, a first CSMA / CD transmission line connected to the computer, a network, and a second CSMA / CD transmission line connected to the network. Transmitting the data from the computer via the first transmission path to the network via the second transmission path, and transmitting the data from the computer via the first transmission path to the network via the second transmission path. And a function code filtering device that causes the computer to receive data from the network via a first transmission path. The function code filtering apparatus includes a transmission / reception buffer and a transmission / reception buffer via the second transmission path. First means for determining whether or not the data received from the above network matches the registered filtering parameters. A second means for temporarily storing the data in the transmission / reception buffer when they match, and transmitting and receiving the data to / from the computer via the first transmission path, and the use amount of the transmission / reception buffer exceeding a prescribed amount. A third means for detecting data from the computer and temporarily storing data received from the computer via the first transmission path in a transmission / reception buffer in a state where the data does not exceed a prescribed amount, and A fourth means for transmitting data to the network via the network, and, when data is received via the first transmission path from the computer while detecting that the data exceeds the prescribed amount, the data is transmitted until the data falls below the prescribed amount. Fifth means for sending dummy data to the computer via the first transmission path is disclosed.

Further, according to the present invention, there is provided a function code filtering apparatus, comprising: a mode for performing signal collision detection on a first transmission path side;
Disclosed is an autonomous decentralized system having mode switching means that does not perform signal collision detection.

Further, according to the present invention, the switching means is controlled to a mode for detecting a signal collision on the first transmission line side when the predetermined amount is not exceeded, corresponding to the third means. In a state where the signal collision is exceeded, the mode is controlled so as not to perform the signal collision detection on the first transmission line side, and the fourth means operates in the mode in which the signal collision detection is performed on the first transmission line side. The fifth means transmits the received data to the first transmission line under a mode in which the signal collision detection is not performed on the first transmission line side. An autonomous decentralized system according to claim 2 to be transmitted is disclosed.

In order to achieve the above object, the present invention provides a transmission system comprising a plurality of transmission apparatuses having a function of detecting data collision on a transmission path and retransmitting the data, and a network connecting the transmission apparatuses to form a transmission path. A buffer provided between the transmission device and the network for temporarily storing transmission / reception data; and a buffer for detecting that the amount of use of the buffer exceeds a predetermined amount. And a dummy data sending unit that sends dummy data over the network when the buffer usage detecting unit detects that the usage amount in the buffering buffer unit exceeds a specified amount. When transmission data from another transmission device connected to the transmission path of the network has been transmitted over the network, the transmission data and the dummy To generate collision between over data, prompting the retransmission of the data, characterized in that to prevent the loss of the received data in the transmission device.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a transmission system according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram illustrating a configuration of a transmission system according to an embodiment of the present invention.

The function code filtering device 101 comprises:
Connected between the host computer 102 and the backbone network 103, data required by the host computer 102 is selected and taken from the backbone network 103,
It has a function of reducing the network load of the host computer 102.

In a distributed autonomous network in which transmission is performed without specifying a destination of a message, it is necessary to determine whether or not the data is necessary for itself at a data receiving destination. Therefore, the function code filtering device 101 for destination determination is indispensable. Also, the function code filtering device 101 and the host computer 10
2 and the backbone network 103 are general-purpose CSMA /
They are connected by CD-system transmission lines 104 and 105, and their positions can be considered as in the case of the gateway described in the related art.
01 to the FEP (Front End Processes) of the host computer 102.
sor), and when considered as one system, it is not preferable that data loss occurs during transmission as in the case of a gateway.

FIG. 2 shows a function code filtering device 10.
1 is a configuration diagram of the inside. The apparatus mainly includes a microcomputer 201 that controls overall data processing including filtering processing for data selection, a master network controller 202 that controls data transmission on the backbone network 103, and a slave network controller that controls data transmission on the host computer 102 side. 203, a ROM 204 for storing an arithmetic processing program of the microcomputer 201, a DRAM 20 used as intermediate data for arithmetic operations and a transmission / reception buffer
5 and the like.

FIG. 3 is a flowchart showing processing of data received from the backbone network 103. When the received data from the backbone network 103 is taken into the function code filtering device 101 by the master network controller 202, the data is first registered in the master-side received data management table 206 and then transmitted and received by the transmission / reception buffer 2.
05 is stored.

The filtering task that operates on the microcomputer 201 refers to the master-side received data management table 206 at regular intervals (step 301). When it is confirmed that the received data exists, the filtering task compares the filtering parameter table 212 with the received data. It is determined whether the data is required by the host computer 102.

FIG. 4 shows an example of the structure of a received frame. The header portion preceding the data of the received frame is divided into a MAC header, an IP header, and a UDP header. MAC
The header is a header for media access control and includes a destination address DA, a transmission address, and a protocol IP PT. The IP header contains the protocol P. In addition, the UDP header includes a transmission port number SP, a destination port number DP, a checksum CkSum, and a data length Len.

Of these, two types of protocol parameters PT and destination port number DP are registered as filtering parameters, and only when the received frame is a broadcast frame (that is, when the destination address DA is all 1), the filtering parameter table 212 is stored. The collation of the received data is performed (step 302).

If the result of the determination is that the received frame is other than a broadcast frame, and if the broadcast frame contains data required by the host computer 102, it is determined whether the slave-side transmission queue 210 is full. Step 303), transmission queue 210
If there is free space in the slave-side transmission data management table 2, the data is stored in the slave-side transmission queue 210.
07 (step 304). The master-side received data management table 206 and the transmission / reception buffer 20
5 is released (step 305).

On the other hand, if the data does not meet the conditions in step 302, the data is discarded (step 306), and the data storage section of the master side received data management table 206 and the transmission / reception buffer 205 is released (step 306). 305). On the other hand, if the slave-side transmission queue 210 is full at step 303, the process waits until a space is available.

Next, FIG. 5 is a flowchart relating to processing of transmission data from the host computer 102. In this case, unlike processing of data received from the backbone network 103, there is no need to perform filtering of transmission data, and it is sufficient to manage only data relay to the backbone network 103. However, backbone network 1
When the amount of data flowing on the transmission line 03 is very large, the transmission queue 211 may not be updated as desired due to retransmission processing or the like due to data collision on the transmission path. In this case, there is a possibility that the data up to the transmission / reception buffer 205 becomes full and data cannot be received from the host computer 102.

As described above, it is necessary to avoid that transmission data from the host computer 102 is lost before reaching the backbone network 103. Host computer 10
The transmission data from 2 is registered in the slave-side reception data management table 208 and then stored in the transmission / reception buffer 205. The relay transmission management task operating on the microcomputer 201 is executed at regular intervals by the slave-side reception data management table 20.
8 (step 501), and when it is confirmed that the received data exists, the free space of the transmission / reception buffer 205 is checked (step 502).

If it is determined that the free space of the transmission / reception buffer 203 is insufficient, the slave side transmission queue 2
10 is temporarily frozen, and as shown in FIG.
Dummy data (pseudo-telegram) is stored at the top of 10, and other data is shifted. The transmission queue 210 normally operates one queue as a spare in order to store the dummy data (step 503). Here, the criterion of the shortage of the transmission / reception buffer capacity is one for storing the received data from the host computer 102 and one for the backbone network 103.
It is assumed that the number of receptions is three or less, that is, one for the reception from the server and one for the spare.

When the processing in step 503 is performed, the data transmission mode of the slave network controller 203 is switched to a mode in which collision detection is not performed (step 504), and dummy data is forcibly transmitted on the transmission path. If the transmission data from is present on the transmission path, it prompts retransmission due to collision. Thereafter, the process returns to step 502 and the same process is repeated until the transmission / reception buffer 205 becomes empty.

If it is found in step 502 that there is free space in the transmission / reception buffer 205, the data transmission mode of the slave network controller 203 is returned to the mode for performing collision detection (step 505), and the same as step 303 in FIG. It is determined whether the master-side transmission queue 211 is full (step 506). If there is free space in the transmission queue 211, the data is stored in the master-side transmission queue 211 and registered in the master-side transmission data management table 209. I do. Further, the data storage unit of the slave-side received data management table 208 and the transmission / reception buffer 205 is released (step 507). On the other hand, if the master-side transmission queue 211 is full, step 30 in FIG.
As in the case of 3, it waits until a space becomes available.

Although the problem of excessive or insufficient use of the entire transmission / reception buffer has been a problem, it is divided into buffers for network transmission and reception for a computer, and only the transmission buffer for network data transmission is used. There is a way to make excess or deficiency a problem.

[0026]

As described above, according to the present invention, the use status of the buffer memory is monitored, and when the amount of received data reaches a predetermined amount or more, dummy data is sent out onto the transmission line through which the received data is flowing. By generating a collision and prompting retransmission of data, loss of data in a connected transmission device can be prevented without making a special change to a general-purpose network system represented by the CSMA / CD system. This can reduce the load on the host computer such as data loss check and retransmission processing.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of a transmission system according to the present invention.

FIG. 2 is a block diagram showing a configuration inside a function code filtering device used in the embodiment shown in FIG. 1;

FIG. 3 is a flowchart showing processing of data received from the backbone network in the embodiment shown in FIG. 1;

FIG. 4 is a configuration example of a reception frame used in the embodiment shown in FIG. 1;

FIG. 5 is a flowchart showing processing of transmission data from a host computer in the embodiment shown in FIG.

FIG. 6 is an explanatory diagram of a method of storing dummy data in a slave transmission queue in the embodiment shown in FIG. 1;

[Explanation of symbols]

 101 Function Code Filtering Device 102 Host Computer 103 Backbone Network 104, 105 General Purpose CSMA / CD Network 201 Microcomputer 202 Master Network Controller 203 Slave Network Controller 204 Program Storage ROM 205 Transmission / Reception Buffer DRAM 206 Master-side Received Data Management Table 207 Slave Side Transmission data management table 208 Slave side reception data management table 209 Master side transmission data management table 210 Slave side transmission queue 211 Master side transmission queue 212 Filtering parameter table

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Nao Ogawa 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Hitachi, Ltd. Omika Plant

Claims (7)

[Claims] 1. A computer and a first CSMA / CD system connected to the computer
Transmission line, network, and the second CSMA / CD system connecting to this network
Transmitting the data from the computer via the first transmission path to the network via the second transmission path, and connecting the data to the network via the second transmission path. A function code filtering device for causing the computer to receive data from the network via a transmission line via a first transmission line, the function code filtering device comprising: a transmission / reception buffer; First means for determining whether or not data received from the network via a path matches registered filtering parameters; and if matched, temporarily store the data in the transmission / reception buffer, and Second means for transmitting to and receiving from the computer via the first transmission path, and that the used amount of the transmission / reception buffer exceeds a prescribed amount. A third means for detecting, and temporarily storing data received from the computer via the first transmission path in a transmission / reception buffer in a state where the second transmission path is not exceeded, and A fourth means for transmitting data to the network via a first transmission path from the computer in a state where the data exceeds a prescribed amount, and a dummy until the data falls below the prescribed amount. Fifth means for sending data to the computer via the first transmission path. 2. The function code filtering device according to claim 1,
2. The autonomous decentralized system according to claim 1, further comprising switching means for switching between a mode in which signal collision is detected on the first transmission path side and a mode in which signal collision is not detected. 3. The switching means is controlled to a mode for detecting a signal collision on the first transmission line side when the amount does not exceed a prescribed amount, corresponding to the third means. In the state, the mode is controlled so as not to perform the signal collision detection on the first transmission path side, and the fourth means performs the reception in the mode in which the signal collision detection is performed on the first transmission path side. The fifth means transmits the dummy data to the first transmission line in a mode in which the signal collision detection is not performed on the first transmission line side.
3. The autonomous decentralized system according to claim 2, wherein the signal is transmitted to a transmission line of the same. 4. When data is transmitted from a transmission / reception buffer to a computer via a first transmission path and transmitted to a network via a second transmission path, data is set in a transmission queue and the data is stored in the transmission queue. 2. The autonomous decentralized system according to claim 1, wherein the storage source area is opened. 5. The transmission / reception buffer has a buffer area for transmission to a network and a buffer area for reception to a computer, and a third means determines that the usage of the transmission buffer area exceeds a prescribed amount. The autonomous decentralized system according to claim 1, wherein the autonomous decentralized system is detected. 6. A transmission system comprising a plurality of transmission devices having a function of detecting data collision on a transmission line and retransmitting the data, and a network connecting the transmission devices and forming a transmission line, wherein the transmission device and the network Buffer buffer means for temporarily storing transmission / reception data, buffer use amount detection means for detecting that the use amount of the buffer buffer means has exceeded a predetermined amount, Dummy data sending means for sending dummy data onto the network when the amount detecting means detects the use amount of the buffering buffer means exceeds a specified amount, and wherein the dummy data sending means is connected to a transmission line of the network. If the transmission data from the transmission device is transmitted over the network, a collision occurs between the transmission data and the dummy data, Transmission system prompts the retransmission, characterized in that to prevent the loss of the received data in the transmission device. 7. A collision detecting function stopping unit for temporarily stopping a data collision detecting function for the network when the buffer usage detecting unit detects that the used amount exceeds a specified amount. Even when transmission data from another transmission device connected to a transmission path has been transmitted over the network, the dummy data transmission means transmits the dummy data over the network, and the transmission data and the dummy data are transmitted. 7. The transmission system according to claim 6, wherein a collision is reliably generated between the transmission devices, and the retransmission of the data is promoted to prevent loss of received data in the transmission device.