JPS6281844A - Data transmission system - Google Patents

Abstract

PURPOSE:To prevent overflow by allowing each node of a loop communication network to sent the state of own reception enable/disable to other nodes and controlling the own transmission flow from the state sent from the other nodes. CONSTITUTION:An SV node 10 supervises nodes 11-1n connected in a loop. The nodes 11-1n are connected to plural terminal devices 11-1-11-n, 12-1-12-n...1n-1-1n-n to receive ore send the data. The nodes 11-1n are provided with a means 21 sending the state of own reception enable/disable to the other nodes and a means 22 controlling the own transmission flow depending on the state sent from the other nodes. Thus, it is possible to control the transmission flow by the hardware and the overhead attended with the flow control is reduced.

Description

[Detailed Description of the Invention] [Summary] When multiple nodes are connected, such as in a loop-shaped communication network, in order to prevent the amount of packet communication data that can be sent and received by the mesh body from overflowing, It is a self-controlled data transmission method.

[Industrial Application Field] The present invention relates to a data transmission system in which each node is provided with a control means so that communication is possible without overflowing the amount of data in a communication network using packet communication.

[Prior Art] It is well known to collect transmission information into chunks of a certain length or less, add control information and transmission/reception addresses to form "packets," and transmit and receive the packets. In the loop network shown in FIG. 4, 10 is an S node, which is a node for monitoring and controlling other nodes;
1-1~11-n, 12-1~12-rr-4n-
1 to 1n-n.

When transmitting packets using a loop network, flow control is required to control the amount of packets that can be transmitted. At this time, it is common for the side receiving the packet to constantly notify the sending side of the reception status and for the sending side to control the amount of packets to be transmitted. The most primitive method is to transmit the number of packets that can currently be received to the transmitting side, and the transmitting side transmits only that number. Also, when the number of patches that can stay in the loop is N, on the transmitting side, the number of transmitted
, the number of reports of reception on the receiving side is set to n, and control is performed so that m−n<N, or m−n
=N, the transmission operation is interrupted.

[Problems to be solved by the invention] In the conventional bucket communication network, flow control between sending and receiving is realized by protocol processing, and since the meteor of the bucket is controlled based on the delivery confirmation information of the bucket, Since there is overhead associated with software processing from when the sending side becomes ready until the sending side actually sends data, the throughput cannot be made very high.

Furthermore, since retransmission processing is performed at the data link level, which is a lower level of flow control, when there is a transmission error, the flow at the upper level is automatically suppressed, resulting in a reduction in throughput.

An object of the present invention is to improve the above-mentioned drawbacks, and to perform flow control independently of protocol processing by a processor, so that bucket transmission can be performed at high speed to the fullest possible capacity without overflowing. The object of the present invention is to provide a data transmission method for controlling transmission.

[Means for solving the problems] FIG. 1 is a block diagram showing the configuration of the present invention, and 10 is an SV
Node for monitoring and controlling other nodes, 11
~In is a plurality of terminal devices 11-1 to 11-n at each node.
, 12-1 to 12-n...-In-1 to In-n. Reference numeral 21 indicates means for transmitting the receivable/unreceivable status of the node to other nodes, and 22 indicates means for controlling the own transmission flow based on the status transmitted from the other nodes.

[Operation] Each communication node 11 to In captures an arbitrary vacant slot from among the fixed length slots provided in the unidirectionally circulating frame created in the SV node 10, and divides the message into slots and transmits the message. do. Each node has a reception buffer as a means of transmitting its own receivable/unreceivable status to other nodes, monitors the amount of data inside it, and indicates that it is unreceivable when it exceeds a predetermined value. transmission to the node.

[Embodiment] FIG. 2 is a block diagram showing the configuration of the node shown in FIG. 1 as an embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of frames and slots created by the S■ node. In FIG. 2, 31 is an address comparison section, 32 is a reception bucket buffer, 33 is a buffer amount check section, 34 is a state table in memory, 35 is a microprocessor MPLI, 36
is a transmission bucket buffer, 37 is a delay register, 38 is a controller information section determination circuit, and 39 is a selector SEL.
shows. In FIG. 3, 40 is a data string, 41 is a frame header F, H142 is a slot, 43 is a busy flag BP, 44 is a receive flag RF, 45 is a control information field, 46 is a receiving address, 47 is a sending address, and 48 is data It shows.

Receive flag 44 (RF) and receive bucket buffer 3
2, buffer amount checking section 33, and microprocessor 3
5 is a means 21 for transmitting its own receivable/unreceivable status to other nodes.

Further, the address comparison section 31, the control information section determination circuit 38, the selector 39 (SEL), and the microprocessor 35 serve as means for controlling its own transmission flow based on the state of transmission from other nodes.

First, in FIG. 3, a frame header FH for synchronization,
A plurality of slots form one frame, and each slot includes a control information section 45 and an address information section 46.4.
7 and a data section 48. The control information section 45 includes a busy flag 43 (BF) and a receive flag 44 (R).
F) etc.

When a node transmits data in the transmission bucket buffer 36, it checks in advance whether the other node can receive the data by checking the status table 34 in the memory that shows the status of the other node, and if the other node is able to receive the data. start sending. If it is not possible, the transmission will be waited. At this time, the transmission ready signal to the transmission packet sofa 36 is off.

The receiving operation when the other node is capable of receiving will be explained. The input packet received from the transmission path is judged by the control information part 45 of the data string in the control information part judgment circuit 38, and when it is determined by the address comparison part 31 that the packet is addressed to itself, it is stored in the reception packet buffer 32. It's crowded. At this time, a broadcast packet, which will be described later, is also captured in the same way. A threshold level is determined for the reception packet buffer 32, and is constantly monitored by the buffer amount checking section 33. The threshold level is determined based on round-trip delay amount, transmission speed,
Set a safe predetermined value, including overflow and throat. When the buffer checker 33 detects that the buffer 32 exceeds the threshold level during packet reception, it interrupts the microprocessor 35 and sends out a broadcast packet to all nodes. Broadcast packets are indicated by a receive flag 44 (RF) as being receivable/unreceivable, and the receive address 46 is set to all “0”.
This is a packet addressed to all nodes. When a transmitting node receives a broadcast packet that cannot be received and confirms that the transmitting node is its own destination node, the transmit ready signal is turned off as described above and transmission is interrupted, and the processor process Rewrite the status table 34 in memory.

Further, in the receiving node, when the state of the receiving buffer 32 falls below the threshold level, the receive flag 44 (R
F) Sends a broadcast packet that can be received. At this time, other nodes rewrite their state tables.

Through the operations described above, rapid flow control is performed by hardware processing for the pair of nodes currently communicating, and other nodes check their own status tables before transmitting, so the node currently communicating without causing an overflow.

Furthermore, even in the case of 1:N communication, if one of the nodes receiving data becomes unable to receive data, transmission is interrupted at that point and the node enters a waiting state, allowing for efficient flow control.

[Effects of the Invention] In this way, according to the present invention, the state of the other node can be known before transmission, and at the same time, the state of the other party can be constantly detected during transmission, and the transmission flow can be controlled by hardware. Since this is possible, the overhead associated with flow control can be reduced and the transmission operation can be performed near the maximum throughput of the transmission path.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a diagram showing the configuration of the node in FIG. 1 as an embodiment of the present invention, FIG. 3 is a diagram showing the frame/slot configuration, 4A is a diagram illustrating a conventional loop data transmission system. 10-3 V node 1l-1n-1 communication node 11-1-1n-n-terminal device 21-means for sending reception status

Claims (1)

[Claims] In a data transmission system that transmits packets as units of transmission and reception to a data communication network composed of a plurality of interconnected nodes (11) to (1n), each node has its own information on whether or not it can receive data. A data transmission method comprising: means (21) for transmitting the state of the node to another node; and means (22) for controlling its own transmission flow based on the state transmitted from the other node.