JPS63238735A - Loop type transmission system - Google Patents

Abstract

PURPOSE:To immediately execute connection control even if many calls are generated by dividing a control area into plural different band channels. CONSTITUTION:In case of executing transmission by using a control area having plural divided channels, an office previously sets data in a CPU 7 and a transmission buffer circuit 30 and transmits the leading address of the set data and a channel number to be used to a transmission control part 29. When a channel number obtained at the time of detecting an idle channel coincides with the channel number transmitted from the CPU 7, the control part 29 transmits a transmission request to a transmission timing generating circuit and impresses a transmission timing signal on a transmission buffer 30. Consequently, control data previously set in the buffer circuit 30 are sent to a transmission latch circuit 31 and a selector in accordance with a transmission request.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application) The present invention relates to a loop communication system suitable for application to large-scale networks.

(Conventional technology) With the development of the information society, network systems that connect multiple information systems (stations) to each other via data transmission paths and realize more advanced information processing are becoming popular, such as process control network systems and Various types of network systems have been developed, such as OA network systems and factory automation network systems.

However, recent trends call for the development of large-scale, sophisticated networks that integrate or combine various independently existing networks to enable even more sophisticated reporting processing. The basic requirements for such a large-scale network are: ■ The network must be capable of high-speed, long-distance transmission; ■ It must be compatible with various media such as audio, still images, videos, and coded data. It is a multimedia network that can integrate circuit switching and packet switching, and can accommodate a wide variety of terminals, and can be connected to various types of networks as branch lines.

In order to meet these demands, we have developed a new technology that has excellent compatibility with packet switching and circuit switching systems, and is easy to use optical communication technology and easily construct large-scale network systems, as shown in Figure 7, for example. A loop communication system in which each station is connected in a loop via a transmission path is attracting attention.

The frame format is, for example, the 8th frame format.
As shown in the figure, a frame with a fixed period is divided into a synchronization area, a control area, a circuit switching area, and a packet switching area, and the circuit switching area and packet switching area are used according to the traffic characteristics of the terminal and branch line. That is what is being considered.

Note that circuit switching is transparently realized by providing a large number of slots in the circuit switching area and allocating the slots according to requests from terminals. Connection control data for allocating slots is communicated using, for example, control areas set by dividing the frame.

Incidentally, it has been considered to communicate the above-mentioned connection control data using a packet switching area to control the connection, but this has the problem of reducing throughput when a large-scale network is constructed. There are also problems such as the need to provide a packet switching function even in stations that do not perform packet switching.

There is also the issue of whether to perform the above-mentioned exchange control in a distributed or centralized manner, but if the distributed method is adopted, a blockage bit is required for each slot, and when an error occurs in the blockage bit, There are problems such as complicated recovery. Further, if a distributed method is adopted, there are problems such as difficulty in realizing a directed assignment method.

On the other hand, if a centralized system is adopted, the burden on the control station is heavy, but there are advantages such as easy slot management and a large number of slots since blockage bits are not required.

Under these circumstances, it is considered a good idea to centrally perform connection control by a control station provided within the loop.

(Problem to be Solved by the Invention) By the way, in a large-scale network that accommodates a large number of terminals, simply communicating connection control data using the control area of the frame format described above will generate a large amount of data. There is a problem that calls from terminals cannot be processed completely.

That is, in order to set one slot used for communication between stations, it is necessary to transmit and receive connection control for different information boards several times.

For this reason, when a large number of calls from terminals occur, the probability that the control area is in use increases, and call requests from each station are forced to wait, resulting in frequent connections being unable to receive responses from the control station. This results in a decrease in system performance.

Therefore, it is conceivable to widen the band of the control region shown in FIG.

However, in this case, if the amount of information that can be sent and received in one control area is longer than the connection control message, there is an effect of lowering the probability that the control area is in use. If it is shorter than the control information, the probability that the control area is in use cannot be reduced, but rather the efficiency of using the transmission path will be reduced.

Therefore, it has been considered to divide the control area into a plurality of channels. In this case, the ilJ 911 station can communicate connection control packets with each station using individual channels. In other words, the pipe in the control area used for connection control can be made substantially thicker.

In this case, when the control area shown in Fig. 8 is used as one channel, it is necessary to use the control area band so that the maximum value of connection control data can be sent and received at one time to process a large number of calls. It is also advantageous for processing a large number of calls to configure each channel in the same way even when dividing into a plurality of channels.

However, this means that the speed of the transmission line is very fast,
Furthermore, this is true when the bandwidth of one frame can be set very wide; generally speaking, there is a technical upper limit to the speed of the transmission path, and the bandwidth of one frame must be considered to be finite.

That is, expanding the bandwidth of the control area of a frame with a finite bandwidth reduces the data communication area allocated by connection control, which reduces the number of communicable units in the entire system.

For this reason, for example, by setting the bandwidth of each channel in a control area divided into multiple channels to be smaller than the maximum value of connection control information (for example, the average value of connection control information), redundant parts can be reduced to some extent. However, the control area can also be made smaller to some extent.

But short +7 like control in loop communication system
Both i-information (about a few bytes) and relatively long information such as connection control information (about several tens of bytes) sent and received between equipment that performs line switching such as PBX connected to the outside are Qq. In the case of a system that transmits and receives short information (about a few bytes) such as control within a loop communication system, the band of the control area cannot be used effectively, and lines such as PBX connected to the outside. When sending and receiving relatively long information such as connection control information (about several tens of bytes) that is sent and received between exchanging devices, connection information that cannot be sent and received in one channel is sent and received using the control area several times. must be transmitted. Furthermore, in the latter case where the control area must be used for transmission several times, not only does the transfer take time, but care must be taken regarding the order of transmission or reception. That is, it is possible to determine the order on the receiving side by providing an area for each channel to indicate the order and assigning numbers in the order of transmission, but in this case there is a problem that the procedure and circuitry become extremely complicated.

The present invention was made in response to these circumstances, and its purpose is to provide a large-scale network that can efficiently utilize the control area and quickly control connections even when a large number of calls are made. The purpose of this invention is to provide a highly practical loop communication method suitable for.

[Structure of the Invention] (Means for Solving the Problems) In other words, in the loop communication system of the present invention, a control station and a plurality of stations are connected in a loop via a transmission path, and a control area and a plurality of slots are connected. A frame having a data communication area divided into data communication areas is circulated on the transmission path, a connection control packet is transmitted between the stations using the control area, and the data communication area corresponding to the control area allocated by the control station is transmitted between the stations. In the loop communication method in which data communication is performed between the respective stations using a space allocation in a data communication area, the control area is
It is characterized by being divided into channels of multiple different bands.

(Function) In the loop communication system of the present invention, since the control area is divided into channels of a plurality of different bands, the control station uses each channel to communicate connection control packets with each station. This makes it possible to quickly deal with a large number of calls.

Furthermore, it is possible to select and use a channel with a band suitable for connection control information, and it becomes possible to use the control area efficiently.

Therefore, it is highly practical and suitable for large-scale networks.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of the format of a communication frame according to this embodiment, and A is the format when line exchange and backt exchange are integrated. Example B shows an example format for only circuit switching.

Format A is a synchronization area, an n-channel control area,
It consists of a circuit switching area and a packet switching area.

Format B is synchronization area, n-channel control jII
It consists of an area and a circuit-switched area.

Each channel in the control area of format A and format B described above is set to a different band. This means that the format of each channel in the control area is
As shown in C in Figure 1, the air block display, destination station address,
It is composed of a destination terminal number, a transmitting station address, a transmitting terminal number, a command, data, data length, and check code, and is realized by changing the length of the data among these.

Each of these channels is used individually to communicate connection control packets between each station and the control station.

Note that the number of channels and the bandwidth of the control area to be divided and set are optimally set according to the system scale such as the number of terminals accommodated in the network, the length of the connection control packet, etc. Specifically, the number of channels and the band may be set, for example, at the time of system configuration.

Figure 2 shows an example of the configuration of a station that communicates control information within the loop communication system and connection control information sent and received between devices that perform circuit switching such as PBXs connected to the outside through such a channel. It is.

To explain the configuration and operation of this station, the data received by receiver 1 is converted into serial-to-parallel converter! ? 82 and connected to the connection control section 3, line switching section 4, and packet switching section 5.
are supplied respectively. These connection control section 3, line switching section 4, and packet switching section 5 communicate with each other via the CPU bus 6.
Data is sent and received between the PU 7 and the memory 8 to perform their respective functions.

The frame synchronization detection circuit 9 detects the beginning of the frame from the synchronization signal inserted into the synchronization area, and at this detection timing, the reception timing generation circuit 10 is activated and the slot counter 11 is initialized. This slot counter 11 is connected to the reception timing generation circuit 10.
The timing of each slot is detected by counting the number of word clocks generated.

In accordance with the slot timing signal generated by this slot counter 11, the connection control section 3, line switching section 4,
The packet switching unit 5 knows the input timing of the corresponding received data and inputs the data.

Further, transmission data from this station is transmitted to the connection control section 3 and the line switching section 4 under the control of the transmission timing generation circuit 12.
, from the packet exchange unit 5 via the selector 13, that is, timing-controlled in the format described above, is provided to the parallel-to-serial conversion circuit 14, and transmitted from the transmission fi 15.

The selector 13 selects the signal received via the serial/parallel conversion circuit 2 when there is no transmission data from the station, and supplies it to the parallel/serial circuit 1?314.

This selector 13 allows communication data to bypass the station.

Further, the connection control section 3 is configured as shown in FIG. 3, for example.

That is, the control area detection unit 21 detects the control area of the received frame from the channel number detected and output by the slot counter 11. By detecting this control area, the data in the control area in the received data is changed to the reception latch time tI?
It is taken into I22.

The data taken into this reception latch circuit 22 is used for channel detection in an empty channel detection circuit 23, and
The A monitoring circuit 24 detects whether the data is addressed to the own station. If the data is addressed to the own station, the reception control unit 25 is activated and the reception latch circuit 22
The data stored in the channel is transferred to the area of the reception buffer 26 corresponding to its own channel, and then taken in by the CPU 7. Note that the reception buffer 26 is individually set for each channel. That is, the reception buffer 26 is composed of a memory, and areas are allocated and used for each channel as shown in FIG. Further, boundary detection of each channel is performed by a channel boundary detection circuit 27.

The channel boundary detection circuit 27 detects the channel boundaries of the different bands in which the control area is divided, based on the slot number, word clock, information available at the time of system configuration, and information on the different bands in which the control area is divided as described above. The channel counter 28 counts the detected signals to obtain the channel number.

When transmitting through the II territory controlled by the station, the CPU
7 and the transmission buffer circuit 30, and transmits the start address of the set data and the channel number to be used to the transmission control section 29. When the channel number at the time of detecting an empty channel matches the channel number transmitted from the CPU 7, the two transmission control units give a transmission request to the transmission timing generation circuit 12 and apply a transmission timing signal to the transmission buffer circuit 30. . As a result, the control data previously set in the transmission buffer circuit 30 in accordance with the station's transmission request is transferred to the transmission latch circuit 31.
Control data is sent from this transmission latch circuit 31 via the selector 13.

Note that the transmission buffer circuit 30 is individually set for each channel. That is, the reception buffer circuit 1-830 is composed of a memory, and is used by allocating an area for each channel as shown in FIG. Further, boundary detection of each channel is performed by a channel boundary detection circuit 27.

Further, the line switching section 4 accommodates a plurality of line switching terminals. Then, line switching is performed between the line switching terminals housed in each station. When performing line switching, the line switching section 4
communicates connection information via the CPU 7 and the connection control unit 3 using a control area on the frame.

Further, the packet switching section 5 accommodates a packet switching terminal. Packet exchange is then performed between the packet exchange terminals housed in each station.

Control information between each station is also transferred via the connection control unit 3.

In response to transmission requests from each section, the CPU 7 packetizes information from each section according to the band of the channel to be used. Thereafter, the packetized data is set in the transmission buffer circuit 30, and the set start address and the channel for transmission are notified to the transmission control unit 29. Transmission flil control unit 2
When the transmission operation is completed, 9 notifies the CPU 7 of the completion of the transmission.

Further, when the CPU 7 receives a packet from each section, it interprets the commands and data in the packet, and controls each section for system control, connection control, etc.

Next, in order to explain the operation of the system, short information (about a few bytes) such as the @11 command in the loop communication system will be used.
(assumed to be 10 bytes or less) and connection control information (assumed to be several tens of bytes = 100 bytes or less) sent and received between devices that perform circuit switching are communicated using the control area. Assume a case.

In the control area, the bands of channel 1 and channel 2 are set at the time of system configuration according to the color of these two pieces of information. Here, we are considering a case where the control area is divided into two. Channel 1 is used for short information such as control in a loop communication system (about a few bytes (assuming 10 bytes or less)).
Channel 2 is used for connection control information (assumed to be approximately several tens of bytes or less than 2,100 bytes) sent and received between devices that perform circuit switching.
This is used to send and receive information.

First, when a transmission request for control within the loop communication system occurs, the CPU 7 converts the packet into packets of type 1 (a packet corresponding to the band of channel 1), and transfers the packet to channel 1 of the transmission buffer circuit 30. and notifies the transmission control unit 29 of the set start address and the channel number for transmission. When the transmission operation is completed, the transmission control unit 29 notifies the CPU 7 of the completion of the transmission. When the CPU 7 receives the end of channel 1 transmission, it can transfer the next data to the area corresponding to channel 1 of the transmission buffer circuit 30.

On the other hand, when receiving data addressed to channel 1 or the own station, the CPU 7 disassembles the packet, interprets the commands and data, and controls each section within the station (other than the line switching section 4).

Furthermore, when a transmission request is generated for connection control to be transmitted and received between devices that perform circuit switching, the CPU 7 converts the packet into a paget 2 type packet (a packet corresponding to the band of channel 2), and sends the packet to the transmission buffer circuit 30. , and notifies the transmission control unit 29 of the set start address and the channel number for transmission. Upon completion of the transmission operation, the transmission control section 29 notifies the CPU 7 of the completion of transmission. When the CPU 7 receives the completion of channel 2 transmission, it can transfer the next data to the area corresponding to channel 2 of the transmission buffer circuit 30.

On the other hand, when data addressed to the own station is received from channel 2, CPU 7 disassembles the packet, interprets commands and data, and controls line switching section 4.

Note that in the above example, a case has been described in which the control area is divided into two different bands, but it is also possible to divide it into two or more bands.

In addition, in the above explanation, when an empty channel in an appropriate band is detected, the station uses that channel to transmit data to the control station. In such a case, as shown in FIG. 6, for example, the channel number converter 32 is used to determine whether the channel number detected by the channel counter 28 is available for use at that station, Then, it may be determined whether the channel is empty or not, and the transmission of connection control data may be controlled.

As explained above, in this system, connection control data is communicated between the control station and each station using individual channels of different bands, which are formed by dividing the control area of the frame. , communication of connection control data can be performed efficiently. In other words, by using the empty channel, connection control data can be communicated simultaneously between one control station and a plurality of stations, and slot allocation for line connections can be quickly performed.

In other words, the control area is divided into a plurality of channels, each of which is used independently for communication of connection control data between the control station and the control station, so that the control area pipe connecting the control station and each station is substantially thickened. be able to. Therefore, it becomes possible to quickly process a large number of calls from a plurality of stations.

Furthermore, since communication is performed using a channel with a band suitable for connection control information, the control area can be used efficiently.

It should be noted that the present invention is not limited to the embodiments described above, and can be implemented with moderate modifications without departing from the gist thereof, and can be applied to various network systems.

5 Effects of the Invention] As explained above, according to the loop communication method of the present invention, the control area can be used efficiently and connection control can be performed quickly in response to a large number of calls. It is highly practical and suitable for large-scale networks.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the format configuration of a communication frame in an embodiment of the present invention, FIG. 2 is a diagram without showing an example of the configuration of a station, and FIG. 3 is a diagram showing an example of the configuration of a connection control section of a station. Figure 4 is a diagram for explaining the area setting of the reception buffer circuit of the connection control unit, Figure 5 is a diagram for explaining the area setting of the transmission buffer of the connection control unit, and Figure 6 is a diagram for explaining the area setting of the transmission buffer circuit of the connection control unit. FIG. 7 is a diagram showing a schematic configuration of a loop network, and FIG. 8 is a diagram showing an example of a format configuration of a communication frame in a conventional system. 3...Connection control unit 4...Line switching unit 5...Paget switching unit 7...CPU 9... Frame synchronization detection circuit 10...
...Reception timing generation circuit 11...
...Slot counter 12...Transmission timing generation circuit 13...Selector 21...Control nm, area detection circuit 23...
...Empty channel detection circuit 24...
・DA monitoring circuit 25...Reception control section 27...Channel boundary detection circuit 28...
......Channel counter 29...
・Transmission control unit 32...Channel number comparator applicant
Nippon Telegraph and Telephone Corporation Applicant Toshiba Corporation Representative Patent Attorney Sasu Suyama - Figure 1 Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) A control station and a plurality of stations are connected in a loop via a transmission path, and a frame having a control area and a data communication area divided into a plurality of slots is circulated on the transmission path, and the control area is In a loop type communication method, a connection control packet is transmitted between the stations using the connection control packet, and a slot in the data communication area allocated by the control station according to the contents of the connection control packet is used to perform data communication between the stations, A loop communication system characterized in that the control area is divided into channels of a plurality of different bands. (2) The loop communication system according to claim 1, wherein a control area channel that can be used for communication from a station to a control station is specified.