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Relay device and data transfer method

A relay device and data transmission technology, applied in the direction of data exchange through path configuration, digital transmission system, data exchange network, etc., can solve the problems of additional, inability to eliminate delay jitter, and fluctuation of high-priority frame transmission delay time, etc. To achieve the effect of preventing delay jitter

Active Publication Date: 2016-12-14
MITSUBISHI ELECTRIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for the store & forward method, even with the aforementioned priority queue, the delay jitter cannot be eliminated
The reason for this is that in the store & forward method, if a high priority frame is input while a low priority frame is being sent, it must wait until the transmission of the low priority frame is completed, resulting in a delay in the transmission of the high priority frame fluctuate
[0004] At the output port, as long as a transmission conflict between a high priority frame and a low priority frame occurs, the delay jitter determined by the maximum frame length and transmission speed of the low priority frame may be added to the transmission delay time of the high priority frame

Method used

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  • Relay device and data transfer method
  • Relay device and data transfer method
  • Relay device and data transfer method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0038] figure 1 It is a diagram showing a configuration example of the relay device 1 according to the first embodiment. The relay device 1 has a frame determination unit 2 , a fixed delay queue 3 , a low priority frame buffer 4 , a transmission frame selection unit 5 , a retransmission buffer 6 , and an output control unit 7 . In this embodiment, the low-priority frame storage means is constituted by the low-priority frame buffer 4 and the retransmission buffer 6 .

[0039]The frame judging unit 2 is a judging unit that assigns a high priority to each output port of a received frame using an identifier defined in a header or a payload of a received frame as a judgment criterion. frames and low priority frames. Here, the high-priority frame is a frame with a special priority, and the other frames are low-priority frames, which are frames with a lower priority than the high-priority frame.

[0040] The fixed-delay queue 3 is a high-priority queue that stores high-priority fr...

Embodiment approach 2

[0062] In Embodiment 1, the retransmission buffer 6 is provided separately from the low-priority frame buffer 4, but these are not necessarily provided independently. In Embodiment 2, a case where retransmission can be performed from a low-priority frame buffer will be described. In addition, the same code|symbol is attached|subjected to the same structure as Embodiment 1, and detailed description is abbreviate|omitted.

[0063] Figure 5 It is a figure which shows the structural example of the relay apparatus 1a concerning Embodiment 2. With respect to the relay device 1, in the relay device 1a, the retransmission buffer 6 is deleted, and the low-priority frame buffer 4, the transmission frame selection unit 5, and the output control unit 7 are replaced with low-priority frames Buffer 4a, transmission frame selection unit 5a, and output control unit 7a. In this embodiment, the low-priority frame buffer 4a is a low-priority frame storage unit.

[0064] The low-priority fra...

Embodiment approach 3

[0086] In Embodiments 1 and 2, the operation of the relay device having a two-port configuration was described, but as an example, the number of ports of the relay device is not limited. Therefore, for a relay device having three or more ports, the same structure as the relay device in Embodiments 1 and 2 is also feasible. In the case of a configuration with three or more ports, for input frames from a plurality of ports output from the frame determination unit 2 of the relay device according to Embodiments 1 and 2, it is necessary to make the frames of the same priority Transmissions are pre-processed in such a way that they do not conflict. In this embodiment, a description will be given of a collision control method for high-priority frames in a relay device having three or more ports. In addition, the same code|symbol is attached|subjected to the same structure as Embodiment 1, 2, and detailed description is abbreviate|omitted.

[0087] Figure 8 It is a figure which sh...

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Abstract

The purpose of the present invention is to obtain a relay device which inhibits the occurrence of delay jitter in a general-purpose network, and which is capable of transferring, with high priority and a fixed delay, frames having a special priority level. The present invention is provided with: a frame determination unit (2) which, on the basis of identifiers, divides received frames into high-priority frames and low-priority frames for each output port; a fixed delay queue (3) which delays the high-priority frames by a time period of at least the sum of a specific transmission interval and a frame length with which frames can be received and transferred or discarded normally in a subsequent-stage device, and transmits the high-priority frames; a low-priority frame storage means for storing the low-priority frames; a transmission-frame selection unit (5) which, in cases when the high-priority frames are to be transmitted, implements control whereby transmission of the low-priority frames is suspended, and the low-priority frames are retransmitted; and an output control unit (7) which, on the basis of the control by the transmission-frame selection unit (5), selects the frames to be transmitted to the subsequent-stage device.

Description

technical field [0001] The invention relates to a relay device and a data transmission method. Background technique [0002] Currently, the use of Ethernet (registered trademark) is increasing in the industrial field, and an FA network, a communication network that connects FA (Factory Automation) devices such as PLCs (Programmable Logic Controllers), inverters, and sensors, is constructed at manufacturing sites. In an FA network, in order to realize high-speed and high-precision motion control, the relay device is required to transmit frames sensitive to delay fluctuations with a constant delay time, that is, a fixed delay. Examples of fixed-delay frames that need to be transmitted with a fixed delay include frames used for time synchronization between FA devices, and the like. [0003] In a general relay device, a store & forward (store & forward) transfer control method that accumulates and outputs the entire frame is used. For the store & forward method, it is possible...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L12/28H04L12/865H04L47/56H04L47/32H04L47/6275
CPCH04L47/2433H04L12/4625H04L47/56H04L47/6215H04L47/32H04L47/6275
Inventor 中安俊行谷口幸子
Owner MITSUBISHI ELECTRIC CORP