JPH0763162B2 - Slot access method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slot access method, and more particularly to a slot access method capable of efficiently communicating synchronization information.

[Conventional technology]

The access method in the conventional voice and image information network has been described in a paper ["A study of high-speed multimedia integrated LAN"].
Hamada et al. IEICE Information Network Research Material IN
85-28], the circuit switching system was used.

[Problems to be solved by the invention]

FIG. 2 shows a frame format in the conventional example, and
A time slot format is shown. The circuit exchange area (KE) is used for voice and image communication. Further, as the packet information, the packet in which the exchange area (EX) is vacant is used. In the circuit switching system shown in FIG. 2, since m channels (CHl to CHm) for circuit switching are connected, there is basically no variation in transmission delay in communication of synchronous information such as voice and image information. It is suitable. However, when the number of channels is large but the channel usage rate is low (for example, in-house FAX, videophone, videoconference, etc.), if the circuit switching method is used, each channel is fixedly assigned to each time slot. As the number of channels increases, the speed of the transmission line increases and the efficiency of the transmission line decreases. Also,
Since the above-mentioned slot allocation is generally performed by the management node, in order to dynamically change the slot allocation, a communication protocol for dynamically allocating slots is required between the management node and other nodes. Becomes

It is an object of the present invention to provide an access method that realizes high transmission path efficiency when the usage rate of channels for communicating synchronization information is low.

Another object of the present invention is to provide a slot access method that eliminates variations in transmission delay and allows each node to temporarily occupy a slot for transmitting synchronous information without the need for intervention of a management node. To do.

[Means for solving problems]

In order to achieve the above object, the slot access method of the present invention connects a plurality of nodes including a synchronous information communication device and an asynchronous information communication device by a ring-shaped transmission line,
In a communication system in which a communication frame composed of a plurality of slots is circulated on the transmission path to perform inter-node communication, (a) each slot of the communication frame precedes a data field and indicates a destination indicating the destination of the data. Each node having an address field and a transmission source address field indicating a transmission source of data, and (b) each node having transmission data sets a slot in which a specific code indicating a token is set in the transmission source address field as an empty slot. And the destination device address, the source address field, and the data field of the slot, respectively.
The data transmission operation is performed by setting the own device address and synchronous or asynchronous transmission data, and (c) the receiving side node addressed in the destination address field of any slot is included in the data field of the slot. When there is data to be sent to the above-mentioned source node, the destination address field and source address field of the slot are set to a new destination device address and own device address, respectively. Rewrite, send the transmission data from the device itself to the data field of the slot to perform the data transmission operation, and (d) the node that has completed the data transmission operation receives the slot containing the device address in the source address field. When this occurs, set the above specific code in the source address field of the slot. Characterized by the free slotted by.

[Action]

In the circuit switching system, even if the usage rate of channels for transmitting synchronization information is low, if the number of channels increases, the number of time slots increases, so it is necessary to increase the transmission rate. This is equivalent to a decrease in transmission line efficiency. This phenomenon is due to the fixed assignment of each slot to each channel.

As one means for improving the transmission line efficiency, there is a token passing method. However, the token passing system is generally not suitable for synchronous information communication because the transmission right acquisition waiting time depends on the traffic of other channels and causes communication delay variations. Therefore, in order to efficiently communicate the synchronization information, it is desirable to use the access method that has the features of the circuit switching method and the token passing method.

In the present invention, firstly, in order to improve the efficiency of the line, channels are not fixedly assigned to each slot, and each channel can commonly use the slot. In order to realize this, the source is transmitted to each slot. And the address information of the destination is added. The source address reveals the slot using node, and a specific address is used to indicate an empty slot state. When the channel usage rate is low, the slot is shared by more channels, and the rate of increase of the slot is kept lower than the rate of increase of the channel.

Second, in order to enable synchronous information communication in the first slot format, the channel that once occupies the slot should be controlled to preferentially occupy the slot until a series of communications is completed. There is no variation in communication delay, and synchronous information communication is possible. At this time, attention is paid to the slot after being received by the destination channel. In the case of asynchronous data communication, the slot is usually used to make a response. However, in synchronous information communication, a slight data error can be tolerated, so a response is unnecessary. Therefore, if the receiving channel can also perform data transmission to the transmission source channel using the receiving slot, the two channels can perform synchronous information communication using one slot, and the efficiency is improved. To do.

Example of Invention

Figure 3 shows the network configuration. A plurality of communication control devices 2 to 5 are connected to the transmission line 1, and communication devices 6 to 10 are connected to each communication control device.

The communication devices 6 and 10 are synchronous information communication devices, and 7 to 9 are asynchronous information communication devices.

Hereinafter, one embodiment of the present invention will be described in detail. FIG. 1A shows a frame (Fi) format, and FIG. 1B shows a time slot format. Frame is type 1 and type 2
It consists of two types of slot groups. TYPE1 is a slot for synchronous information communication such as voice and image, and this slot is used during communication between the devices 6 and 10 in FIG. TYPE2 is a slot for data communication which is asynchronous information, and is represented by 7 to 7 in FIG.
This slot is used at the time of communication between devices of No. 9. Slot is
TYPE1 or TYPE2 identification flag (F), 7-bit configuration destination address (DA), 7-bit configuration and slot control address, and (7F) 16 token control address (TC) ), Free token flag (TCF), transmission data (Data),
And frame check code (CRC). However, in TYPE1, CRC is unnecessary because some bit errors can be tolerated due to the nature of the information.

FIG. 4 shows a TYPE1 frame reception determination processing flow chart, FIG. 5 shows a TYPE2 frame reception determination processing flow chart, and FIG. 6 shows a TYPE1 and TYPE2 common processing section flow chart. There are four types of operation statuses of reception, transmission, relay and response judgment as the reception judgment processing result.
Since the processing operation is not peculiar to the present invention, detailed description thereof will be omitted.

The reception determination processing of TYPE1 will be described in detail with reference to FIG. If a TYPE1 frame is received at 301, at 302,
The receiving DA is compared with the own device address (SA) of each device. If DA = SA, the judgment of TC is made at 303, and if TC ≠ 7F, the following data is regarded as self-addressed information and the receiving operation is carried out. At this time, the transmission operation is also performed in parallel. Whether or not there is a transmission request is also determined in 305, and if there is a transmission request, TCF = 308 in 308.
1, DA = TC, TC = SA, and send data. On the other hand, if there is no transmission request, the response flag is set at 306 (TFC =
After 1), send. When TC = 7F in 303, this slot is an empty slot. In FIG. 6, 503, it is determined whether or not there is a transmission request. If there is a transmission request, TCF = 0, TC = S
Set A, set DA, and send data. On the other hand, when there is no transmission request, the received information is relayed without changing.

If DA ≠ SA in FIG. 4 302, it is determined in 310 whether the slot has the right to use the device itself. If TC ≠ SA, the slot use right is in another device or the slot is empty.

This judgment is made in FIG. When TC = 7F, this slot is an empty slot, and the presence / absence of a transmission request is determined in 503, and the operation of 504, 505, or 506 is performed depending on the result. When TC ≠ 7F at 502, it is considered as a slot for other party and other party and relay operation is performed.

On the other hand, in the case of TC = SA in FIG. 4 310, the own device has the slot possession right. At 311 it is determined whether there is a transmission request. If there is a transmission request, set TCF = 0 at 312,
Send data. If there is no transmission request, it is judged in 313 whether or not the communication is completed. If it is not completed, the relay operation is performed and the exclusive right is held. If it is completed, in 314. Set TC = 7F and make the slot an empty slot.

The reception determination processing of TYPE2 will be described in detail with reference to FIG. Four
When DA = SA at 02, TC is determined at 403. TC = 7F
At the time of, it is an empty slot.
The subsequent processing is performed. On the other hand, when TC ≠ 7F, the following data is the data addressed to itself and the response flag (CTF) is set and transmitted.

If DA ≠ SA in FIG. 402, it is determined in 406 whether the data is spontaneous data. When TC ≠ SA, it is the data from another source or the other destination, or an empty slot, and the processing after 501 in FIG. 6 is performed as in TYPE1. If TC = SA, it is voluntary information, 40
The response is judged at 9 and TC = 7F at 407, and this slot is set as an empty slot.

According to the present embodiment, by indicating the right to use the slot by the TC, it is possible to improve the transmission efficiency in the network with less traffic as in the token passing system, and the processing shown in FIGS. The TYPE1 method enables synchronous information communication. Furthermore, the same device can occupy the same slot continuously for more than two rounds on the ring by the TYPE2 method, which enables load-balanced data communication.

〔effect〕

According to the present invention, in a network communication control device that communicates synchronization information, when the channel usage rate is low,
It is not necessary to secure slots for the number of channels, and since the data reception channel can also transmit data, the transmission line efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a frame format and slot format according to an embodiment of the present invention, FIG. 2 is a frame format and time slot format in the conventional system, FIG. 3 is a schematic diagram of a network structure, and FIG. TYPE 1 reception determination processing flow chart in the embodiment, FIG.
TYPE 2 reception determination processing flow chart, and FIG. 6 is a processing flow chart common to FIGS. 3 and 4.

Claims (3)

[Claims] 1. A plurality of nodes including a synchronous information communication device and an asynchronous information communication device are connected by a ring-shaped transmission line, and a communication frame composed of a plurality of slots is circulated on the transmission line to perform inter-node communication. In the slot access method in the communication system, each slot of the communication frame precedes a data field and includes a destination address field indicating a data destination and a source address field indicating a data source. Each node having transmission data determines that a slot in which a specific code meaning a token is set in the transmission source address field is an empty slot, and a transmission destination address field, a transmission source address field and a data field of the slot. Destination device address, own device address, synchronization Or, the data transmission operation is performed by setting asynchronous transmission data, and the receiving node addressed by the destination address field of any slot receives and processes the data contained in the data field of the slot. , If there is data to be transmitted to the source node, the destination address field and source address field of the slot are rewritten to new destination device address and own device address, respectively, and the data field of the slot is rewritten. When the node that has sent the transmission data from its own device to perform the data transmission operation and has completed the data transmission operation receives the slot containing the own device address in the source address field, the source address field of the slot By setting the above specific code to Slot access method characterized by and. 2. A reception side node designated by the transmission destination address, if there is no data to be transmitted to the transmission source node, transmits information indicating a reception response to a predetermined position of the slot. The slot access method according to item 1, wherein 3. A plurality of slots are divided into a synchronous information communication slot group and an asynchronous information communication slot group in advance, and each data source node corresponds to a type of transmission data handled by its own device. The first feature is that the group determines an empty slot and performs the data transmission operation.
The slot access method according to item 2 or item 2.