JPS58159035A - Data communicating system - Google Patents

Abstract

PURPOSE:To raise utilizing efficiency of a channel and to prevent an overhead time due to acquisition and release of the channel, by always monitoring a utilizing state of common transmission line, and executing the acquisition and release of the channel in accordance with its state. CONSTITUTION:In case whan a utilization factor of a channel is comparatively low, the number of channels is sufficient, therefore, as soon as a link is set, acquisition of a channel is executed, and until the link is released, the channel is not released. In this way, the overhead is reduced and the response is improved. Subsequently, when a utilizing state of the channel becomes considerably dense, each communication node device acquires the channel only when transmitting a data, in order to use in common the channel effectively, and releases the chennel in other time. In this way, the transmission line throughput is improved, and the response time is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data communication system in which a plurality of communication node devices are connected to a common signal transmission path and data is communicated between each node device. The present invention relates to a data communication method suitable for reducing.

The conventional Yuzu data communication system has two representative systems as shown below.

The first method is to establish a logical link between communication nodes and at the same time acquire the right to use the channel, and during that time, regardless of the presence or absence of data on the common transmission path, until the communication between the communication nodes is completed. This method does not release the channel.

The second method is a method in which a logical link is established between communication nodes and then a limited channel usage right is acquired during data transmission.

These methods had the following drawbacks.

First, in the first method, the channel is exclusive even while data transmission from the terminal is interrupted.
Other communication node devices cannot use that channel. This has the drawback that under conditions where the utilization rate of the common transmission path is high, the waiting time for the communication node device to acquire a channel increases, and the response time increases.

The latter second method is based on the fact that under conditions where the utilization rate of the common transmission path is high, each communication node device acquires and releases a channel each time it transmits data.
Channel usage efficiency is increased. However, when the utilization rate of the common transmission path is low, channel usage efficiency is hardly a problem; on the contrary, acquiring and releasing channels for each packet increases overhead time. The disadvantages are greater.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data communication system that increases channel utilization efficiency and prevents increases in overhead time due to channel acquisition and release.

In order to achieve such an objective, in the present invention, since the amount of traffic from a terminal changes variously depending on the day or the time of the day, in order to accurately respond to such changes in status, The feature is that the usage status of the common transmission path is constantly monitored, and channels suitable for the situation are acquired and released. :,.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the overall system configuration of the data communication method of the present invention is as follows.
This will be explained with reference to FIG.

In the figure, an optical fiber, for example, is used as a common transmission line in the form of an IF'i loop. 2 is a node device connected to this transmission path. Reference numeral 3 denotes a terminal device connected to each node device 2, which includes a computer, a data terminal device, a facsimile machine, a control device, an exchange, a telephone, and the like.

In the method of the present invention, in the loop-shaped transmission line 1 described above,
Information in a bit string is transmitted, and a group of consecutive bits having a fixed number of bits is herein referred to as a channel. Furthermore, a group of a certain number of consecutive channels is called a frame.

This channel is formed of, for example, 10 bits, the first bit being A. is used to display vacancies.

i.e. #' if you are using that channel! ,
A, beep) @1', °O if not in use
” is set to indicate whether the channel is empty or occupied. A group of channels configured as described above circulate on a common transmission path.

Here, the configuration of the node device shown in FIG. 1 is shown in FIG. 2.

Now, when there is a transmission request from the packetization device 7, the processing device 4 detects it. The packet interface section 5 looks at the empty/busy indicator bit AO of each channel taken in from the transfer control section 6 and counts the number of empty channels for one frame. Here, the count value is compared with the system setting value N0, and the result is passed to processing device #4.

The system setting value N0 is such that the channel utilization rate is low when the number N of empty channels is N>NO, and high when N≦No.

The processing device 4 switches the channel acquisition pattern according to the number of empty channels. FIG. 3 shows the processing flow described above.

FIG. 4 shows a channel acquisition pattern when N>No, and FIG. 6 shows a pattern when N≦N0.

First, Figure 4 shows that when the channel utilization rate is relatively low,
That is, the time chart shows a situation in which each terminal can acquire a channel without "waiting". In the above situation, there is enough room in the number of channels, so the system acquires the channel at the same time as the link is set up, and does not release the channel until the link is released. This is expected to reduce overhead and improve response.

In this way, when the amount of traffic in the network increases and there is no more room for the channel while continuing to monopolize the channel (N≦No), the communication node device forcibly releases the proprietary channel, It is possible to switch the channel acquisition pattern as shown in FIG. Also, after acquiring a channel, if no take is sent to the channel for a certain period of time, the channel is automatically released. It is also possible to consider a method in which the above-mentioned "fixed time" is changed depending on the traffic situation within the network.

Next, FIG. 5 shows a method of acquiring a channel when the usage status of the channel is dense. Under such circumstances, the waiting time for channel acquisition becomes long, leading to an increase in response time. Therefore, in order for each communication node device to effectively share the channel, it is necessary to acquire the channel only when transmitting data, and to release the channel at other times. This makes it possible to improve transmission line throughput and response time.

In this embodiment, each communication node device monitors the status of the common transmission path and performs the above-mentioned processing according to the result. In addition, a central monitoring communication node is provided, and the common The state of the transmission path is constantly monitored, and general communication nodes
A method could also be considered in which inquiries are made here when necessary.

According to this embodiment, each communication node can know the usage status of the common transmission path at any time, and there is an effect that efficient data communication is possible according to the status.

FIG. 6 Fi shows the configuration of an embodiment of the packetization device 7 in FIG. 2, and the processing device 11. Memory 12゜Terminal interface 131 Pass controller draw? It consists of 15 14° buses.

In such a configuration, the processing unit [11] packetizes the data sent from the subscriber terminal 3 via the terminal interface 13, and sends the data to the transfer control unit 6 via the packet interface unit 5, or transfers the data. Packetized information inputted from the control unit via the packet interface unit 5 is transferred to each subscriber terminal 3. Further, the bus controller 14 controls the bus 15.

FIG. 7 shows an example of a specific configuration of the packet interface unit 5 in FIG. 2, in which 21 is a bus controller;
2 is a hunt flag flip-flop, 23 is an acquisition flag flip-flop, 24 is a empty flag flip-flop, 25 is a free flag flip-flop, 26 is a channel counter, 27 is a transmitting channel register, 28 is a receiving channel register,
29 and 30 are comparators, 31 is a packetization device
In the Tough Ace section, 33 and 34 are gates, 35 is a reception buffer, 36 is a transmission buffer, 37 and 38 are serial-to-parallel converters, and 39 is a clock generator.

In such a configuration, when the packetization device 7 issues a channel hunching request, the /%nt flag flip/flop 22 is set via the packetization device interface section 31. When this flip-flop 22 is set, the processing device 4 of FIG. 2 finds and hunts for an empty channel. Upon hunting, the processing device 4 sets the acquisition flag flip/flop 23 and sets the channel number in the transmission channel register 27. The data from the packetizer 7 is backprinted in 8-bit units by a serial-to-parallel converter 38 and transferred to a transmission buffer 36. On the other hand, the channel 1' counter 26 always monitors which channel is currently passing through the loop. Then, it is compared with the value set in the transmission channel register 27 by the comparator 29, and if they match, the gate 34 is opened. At this time, the 8 bits stored in the transmission buffer 36 are sent out onto the loop transmission path. The hunted channel is released as follows: When a release request is issued, the empty flag flip/flop 25 is set through the packetizer interface section 31. This set of flip-flops 25 is connected to the processing device 4 in FIG.
, the corresponding channel is released and register 2 is detected.
Clear the transmission channel number set to 7.

Next, the flow when receiving data will be explained.

When notified of the p1 channel number by packetized data from the other node, the receiving channel is set in the receiving channel register 28. From then on, when a channel with that number passes, it is detected by the comparator 30 (the contents of the channel counter 26 and the receiving channel number in the register 28 match), and the gate 33 is opened. This causes the data to enter the reception buffer 35. This data is subjected to serial-to-parallel conversion by a serial-to-parallel converter 37 and packetized by a packetizer i7.
going out to

The counter 24 counts the number of busy channels among the channels flowing on the loop transmission path. Further, the clock generator 39 provides timing for transmitting and receiving data to the packetizer f7 and timing for serial-to-parallel conversion.

Note that R/W is a continuous output/write signal, D is data, and ID
LE is an empty signal, CHACT is channel count information,
I'LD is received data, SD is sent data, T, CLK
is the timing clock, BUSY is the busy signal, FRE
E is free signal, NO is channel number, C0INI, C
0IN2 indicates a match signal.

Further, the transfer control unit 6 in FIG. 2 has the role of taking in data from the loop transmission line 1 and sending data to the loop transmission line 1, and can use a general signal transmission/reception circuit. However, for example, %Gan Sho 56-1190
This can be realized with the circuit shown in No. 66.

As described above, according to the present invention, it is possible to switch the channel usage right acquisition format according to the usage status of the common transmission path, so that a highly efficient channel that is suitable for the amount of traffic in the network can be created. This has the effect of reducing utilization, reducing overhead, and improving response time.

[Brief explanation of the drawing]

FIG. 1 is an overall system configuration diagram of the data communication system of the present invention, FIG. 2 is a configuration diagram of an example of the node device in FIG. 1, and FIG. 3 is a flowchart for selecting channel acquisition patterns.
FIG. 4 and FIG. 5 are time charts showing the timing of link setup/release and channel acquisition/release;
6 and 7 are concrete configuration diagrams of the packetizer and packet interface section of FIG. 2, respectively. DESCRIPTION OF SYMBOLS 1... Common transmission path, 2... Node device, 3... Terminal device, 4... Processing device, 5... Packet interface section, 6... Transfer control section, 7... Packet conversion device. 1 Figure fi Figure 2 Figure 3 41 yen] Figure 5

Claims (1)

[Claims] In a data communication system in which a plurality of node devices are connected to a common signal transmission path, such as at least one channel, and data is communicated between each node device, the utilization rate of the channel is investigated. If the channel utilization is relatively low, do not release the channel from link setup to link release, and if the channel utilization is relatively high,
A data communication method characterized by acquiring a channel only when transmitting data.