JPH0225579B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a data transmission system, and in particular, a system in which a large number of data processing devices, such as minicomputers, personal computers, pocket computers, etc., are connected through a transmission line to mutually transmit data. The present invention relates to a data transmission system that performs.

<Prior Art> In recent years, data processing devices for personal use, such as personal computers and pocket computers, have been developed and are rapidly becoming widespread, leading to an era in which each person has one device. Large offices are often equipped with this type of data processing equipment equal to the number of employees, and in order to make effective use of these data processing equipment, data transmission between the equipment or sharing of printers, desks, etc. is required. Data transmission systems, etc. are becoming necessary.

However, this type of data transmission system that has been used in the past has limitations such as a limited number of connected terminals (1000 or less) and a short total network distance (2 km or less). The drawback was that the scope of use was limited.

In order to solve these problems, the special public
Publication No. 31861 discloses a multi-dimensional address control device that enables information exchange between arbitrary multi-computer system constituent devices in a multi-computer system in which a plurality of central processing units and input/output devices are combined. Disclosed.

This device assigns a window number to each switch window installed at the intersection of a link bus and a dedicated bus or shared bus (bus unit) to which the central processing unit and input/output devices are connected, and When starting an input/output device from a device, the input/output device is specified using an address information word that is a combination of all window numbers passed through and the device number of the final input/output device.

However, since this address information word consists of multiple address fields equal to the number of bus units connected in cascade, the length of the address information word increases as the number of bus units connected to the system increases. The problem is that you have to change it depending on the number of bus units.
For this reason, a common address information word cannot be used regardless of the size of the system, resulting in a lack of versatility.

Furthermore, if the final input/output device that the central processing unit is trying to activate is located in a place with a relatively small number of cascade stages, the address information word always has a certain length even though it is not necessary to use all the fields. address information word must be used,
There was a problem that redundant information had to be transmitted.

Additionally, in general, it is necessary to store routing information from the central processing unit to the final input/output device in order to provide a response from the final input/output device to the central processing unit. For this reason, a dedicated field for this purpose must be provided in the address information word, which is another problem regarding redundancy. Furthermore, since this field also includes the above-mentioned redundancy problem, the field as a whole has a very high degree of redundancy. Redundancy of such transmitted information has been an important problem that affects the performance of the system itself, especially in systems with low serial transmission speeds.

<Objective of the Invention> The present invention eliminates the drawbacks of the conventional data transmission systems described above and provides a system that does not impose restrictions on terminal equipment or networks. In other words, by connecting multiple networks to which a large number of terminals can be connected, using a network coupling device, and transmitting data using the same protocol across all networks, it is possible to easily expand the number of terminals, and in principle have an infinite number of terminals. In principle, this makes it possible to transmit data over an infinite distance, and
By suppressing redundancy in transmitted information, a data transmission system that is extremely useful even in systems with low serial transmission speeds is provided.

<Embodiment> FIG. 1 is a diagram showing a part of a network configuration example of the present invention. In the figure, 1 to 8 are transmission lines within the same network, and the transmission lines 1 to 8 include data processing devices such as personal computers and pocket computers, which are determined depending on the installation location and convenience of use. (hereinafter simply referred to as terminals) 11 to 65 are connected. The transmission lines 1 to 8 are connected to other transmission lines via network coupling devices 120 to 560 (the number ijo indicates that the network is installed at a position where transmission lines i and j are coupled), The terminals connected to each transmission path are coupled to each other. Although the ends of the connection ends drawn out from the network coupling devices 170 and 580 are not shown in blocks,
It shows that this network is further expanding,
It can be inferred that both the number of terminals and the total length of the network can be increased virtually infinitely.

Next, the data transmission operation will be specifically explained using the above network configuration diagram. For ease of understanding, it is assumed that the addresses of all terminals and network coupling devices consist of 8 bits (1 byte).

During data transmission, a transmission packet is sent out from the sending side, and address information for controlling the data passage route is written in the address field provided in the transmission packet P. In this embodiment, the first byte is A ₁ (address length display section) is always written with the value of the number of bytes in the address section minus 1, and the second byte A ₂ (transmission address display section) indicates the number of bytes connected to the transmission line to which the transmission packet is sent and the next one. The address of the terminal or network coupling device to which the data should be taken is written in, and the address of the route through which the data should pass is sequentially written in the third and subsequent bytes (address storage section). In this embodiment, when the transmission path spans multiple stages, the fourth byte and subsequent bytes are also used, but the information is rearranged between each byte so that the first to third bytes in the address field of the transmission packet have the above relationship. is executed.

First, a case will be described in which data is transmitted from the terminal 11 installed on the same transmission path, for example, the transmission path 1, to the terminal 17. FIG. 2 particularly shows the address part of the transmission packet P for the above data transmission operation. The first three bytes _A1 to _A3 of the transmission packet are occupied by the address part, and the first byte _A1 is 1), that is, a value of 3-1=2 is written. The second byte A ₂ is the address where the data should be sent next,
In this case, "7" is written as the receiving terminal address because the seventh terminal 17 is targeted in this data transmission operation. Furthermore, the third byte
_A3 is the sending terminal address, and address 1 of the first terminal 11 is written therein.

When a transmission packet P having the above address information is output from the terminal 11 to the transmission path 1, the same transmission path 1
All the terminals 12 to 17 and all the network coupling devices 120 and 170 connected to the packet detect the second byte _A2 of the address part of the transmission packet P, in which address information to be sent next is written, and send it to themselves. Check whether it is the one. The device you have confirmed is addressed to you (in this case, device 17)
receives the transmission packet on transmission path 1.

Next, a case will be described in which data is transmitted from the terminal 11 installed on a different transmission path, for example, the transmission path 1 to the terminal 64 installed on the transmission path 6. In this case, the terminals and network coupling devices that pass from terminal 11 to terminal 64 are 11→
The order is 120→240→450→560→64. Now set the address of terminal 1 to “1” and transmission line 6
The address of the terminal 64 located at the fourth position is "4", the address of the network coupling device 120 between the transmission lines is "11", the address of the coupling device 240 is "13", and the address of the coupling device 450 is "11". "11", and the address of the coupling device 560 is "13". When allocating addresses, even if the connected transmission paths are set to the same address information, a coupling device installed between the two transmission paths generally transfers transmission packets received from one transmission path to the other. Therefore, the terminals and network coupling devices belonging to the transmission path to which the information has been transmitted will not receive the same transmission packet again.

When the addresses are determined as above, each address as seen from the data transmission direction is 1 → 11 → 1
3 → 11 → 13 → 4. Figure 3a shows the terminal 11
1 shows the address part of the transmission packet P sent out to the transmission path 1. The first byte _A1 is set to the value "7" which is the number of address field bytes minus 1 (8-1). The second byte indicates the address of the terminal or network coupling device that should receive the transmitted data on the transmission path on which the transmission packet currently exists; in this case, address 11 of the network coupling device 120 is set. The third byte A ₃ to the eighth byte A ₈ are the addresses of the terminals and network coupling devices through which the data has already passed, and the terminals and network coupling devices to which the data should pass, in the order of passage.
The sending terminal 11 that has already sent the transmission packet is written in _A3 . In the fourth byte _A4 , "0" is written as a mark to facilitate the rearrangement of the next address information. That is, considering the original writing order of address information, "0" is written only in the byte of the part containing the address of the network coupling device that should receive the transmission packet on the transmission path.

Figure 3a shows the address part of the transmission packet at the time it is sent from the terminal 11 to the transmission path _1. Address 11 is written in the second byte A2, and address ₁ of the sending terminal is written in the third byte A3. Rare, 4th byte
A ₄ should contain the address of the network coupling device 240 connected to the other transmission line 2 of the network coupling device 120 located next in the order, but the “0” address is inserted in this part. Address information according to the connection direction is sequentially written from the fifth byte _A5 onwards.

In the transmission packet addressing method described above, each terminal and coupling device only needs to check whether or not its own address is in the second byte _A2 of the address field of the transmitted transmission packet; The information entered in will direct you where to send it.

Now, as shown in Figure 3 a, addresses 7, 11, 1
When a transmission packet with 0, 13, 11, 13, 4 set is sent from terminal 11 to transmission path 1,
All the terminals 12 to 17 connected to the transmission line 1 and all the network coupling devices 120 and 1 are connected to the transmission line 1 in the same way as in the above operation.
70 detects the second byte _A2 of the address field,
Check if it is addressed to you. The terminal that has confirmed that it is addressed to it, in this case network coupling device 120, captures the transmitted transmission packet. The network coupling device 120 takes in the transmission packet shown in FIG. 3a, changes only the address part as shown in FIG. 3b, and sends it to the transmission path 2. In other words, the second byte _A2 's own address "11" is
The 4th byte to which the "0" address was input in step a of Figure 3 is input instead of "0" in _A4 , and the 5th byte is the next byte to which the "0" address is input at the same time. The value entered in item A ₅ is “13”
is transmitted to the second byte _A2 , and the fifth byte _A5 is set to a new "0" address instead.

The transmission packet shown in FIG. 3b sent from the network coupling device 120 to the transmission path 2 is
All terminals and coupling devices connected to the above transmission line 1
Similar to the operation in , it detects the second byte of the address field and checks whether it is addressed to itself. In this case, the network coupling device 240 confirms that the packet is addressed to itself and takes in the transmission packet. In the same way as the network coupling device 120 did, the network coupling device 240 converts the transmission packet b in which the 5th byte is set to the "0" address into the 2nd byte and the 5th byte as a transmission packet c. The 6th byte is changed and sent to the transmission path 4. Similarly, the network coupling device 450 takes in the transmission packet c, changes it into a transmission packet d, and sends it to the next stage transmission path 5, and then the network coupling device 560 takes in the transmission packet d,
It converts it into a transmission packet e and sends it to the network 6. The transmission packet e is received by the terminal 64, and the data transmission from the terminal 11 to the terminal 64 is now completed.

Figure 4 shows each transmission path 1, 2,
The timing of the above transmission packets occurring at times 4, 5, and 6 is shown.

The characteristics of the transmission packets shown in FIGS. 3a to 3e are that the order of the address part in all the packets is changed, and there is no change in the packet size at all; , and it is possible to reply by simply reversing the order. Furthermore, the address assignment of each terminal only needs to be such that it can be identified within the same transmission path, and the address assignment of each network coupling device only needs to be such that it can be identified within the two transmission paths to which it is connected. Therefore, there is a large degree of freedom in address assignment, and the number of address bits may be small.

In addition, methods for single broadcast transmission and group broadcast transmission are shown. Here, broadcast transmission means transmission from one terminal to all terminals connected to all transmission paths, and group broadcast transmission means transmission from one terminal to a certain group, for example, the transmission This means sending to a group of terminals such as terminals on the road, terminals with disks, terminals with printers, etc. In each case, the sending terminal sends a transmission packet only once, and the designated terminal receives all of it. Fifth
The figure shows the transmitted packet.

Broadcast communication is performed by setting the address field to a fixed number of bytes and using a pattern that does not appear in a packet in a one-to-one transmission operation in the first byte. In other words, in the case of one-to-one transmission, the first byte of the address section indicates the number of bytes in the address section, so
In the case of broadcast communication packets, the use of 0 or a very large value (eg, 128 or more) allows distinguishing between both transmission packets. however,
Terminals and network coupling devices are provided with a function in advance to recognize whether a transmission packet is a broadcast communication packet based on the first byte of the address part of the transmission packet and to decide whether or not it should be taken in by itself.

<Effects> A feature of the present invention is that, first, addresses need only be different within the same transmission path, so there is a high degree of freedom in address assignment. Furthermore, even if the number and distance of terminals connected to one transmission path are limited, there is no limit to these in the entire network. Any network access method that does not require a master station may be used, such as the CSMA (carrier sense multiple access) method or the token method, and the same method can be used in all networks. .

Therefore, the present invention can be composed of two types of modules: a terminal and a network coupling device.
Moreover, it is possible to obtain a data transmission system that has great flexibility and expandability in network configuration, and has no limitations on the maximum number of terminals or distance.

Further, according to the present invention, since the address length display section is provided in the address section of the transmission packet, the length of the address section can be configured according to the number of data processing devices on the transmission line through which the transmission packet passes. In addition to the low redundancy of transmitted information, there is no need to change the method of configuring the address section even when a transmission path is added to the system, making it possible to configure an extremely versatile data transmission system.

Further, in the data transmission system according to the present invention, the contents of the transmission address display part of the transmission packet are checked, and if the contents of the transmission address display part match the address of the coupling means to be passed, the transmission packet is taken in. , the contents of this transmission address display section are returned to the position of the control code in the address storage section, and the address information through which the transmission packet should pass next is retrieved from the address storage section and set in the transmission address display section. Since it has a coupling means for setting a control code at the array position from which the address information of the section was extracted, the address information that the transmission packet has passed is stored in the address storage section that was used in the past.
Since the return path information of a transmission packet can be reproduced without providing a special address section, the address section of a transmission packet can be configured with extremely low redundancy.

[Brief explanation of drawings]

FIG. 1 is a network block diagram for explaining an embodiment of the present invention, FIG. 2 is a diagram showing the main parts of a transmission packet, and FIGS. 3 a to 3 e sequentially show changes in a transmission packet according to the present invention. FIG. 4 is a timing chart of a transmission operation, and FIG. 5 is a diagram showing a transmission packet for explaining other operating states. 1 to 8: transmission line, 11 to 65: terminal, 120,
170,230,240,450,560,58
0: network coupling device, P: transmission packet,
A _i : Address part.

Claims (1)

[Claims] 1. An address length display section indicating the length of the address section;
A transmission address display section indicating the address information to be passed next, and an address storage section which arranges the address information in accordance with the passing order and has a control code at the arrangement position of the address information taken out to the transmission address display section are predetermined. A data transmission line for transmitting transmission packets located at a location, a plurality of data transmission devices serving as receiving terminals or transmitting terminals for transmission packets, and coupling means for connecting the transmission lines to each other. In the transmission system, the combining means checks the contents of a transmission address display part of the transmission packet, and if the contents of the transmission address display part match the address of the combining means, takes in the transmission packet. , after returning the contents of the transmission address display section to the position of the control code in the address storage section and retrieving address information through which the transmission packet should pass next from the address storage section and setting it in the transmission address display section, A data transmission system characterized in that a control code is set at a position in an address storage section from which the address information is retrieved.