JPS6046151A - Transmission control method in data transmission system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention detects abnormalities in transmission lines and detours around abnormal locations.

(1) and related to transmission function recovery equipment. In particular, it relates to a device in which transmission path abnormalities cause intermittent transmission errors due to noise or the like.

[Background of the invention]

In the transmission line, loop line disconnection, transmission control equipment (Ne
twork Control Processor:
In response to continuous transmission errors due to failure of NCP (hereinafter referred to as NCP), a total of 4 N
The NCP that sent the test data transmits the test data to a loop (small loop) made up of CPs, and if this test data does not return within a certain period of time, it determines that there is an abnormality in the small loop where the test was performed. A method of configuring a detour route for data transmission to the paired NCP (loop transmission system, patent application 1984-
115300) was proposed earlier.

However, when intermittent transmission errors occur due to noise, etc., this proposed method may accidentally cause data to flow normally, a small loop check for testing to be successfully performed, or a detour to be configured. After the detour is canceled, the result of the test for recovery is normal (2) and the detour is canceled again and again.

[Purpose of the invention]

The present invention was made to solve these problems, and when the abnormality in the transmission line is intermittent, a detour path is temporarily configured, and when the abnormality is restored to normal, the normal transmission path is established. It is an object of the present invention to provide a detection/recovery device for transient faults in a transmission line that can be recovered from and that can accurately detect these faults.

[Summary of the invention]

The present invention performs a plurality of tests and uses the statistics of the test results to detect an abnormality and recover the transmission path even in the case of intermittent transmission errors.

[Embodiments of the invention]

Hereinafter, a detailed explanation will be given by way of example with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a transmission system configuration according to the present invention. 0 and 1 are loop lines, 00-On and 10-1n are transmission control devices (hereinafter referred to as NCP (3)), 20-2n are loop link lines, 300-30n and 310-31. n is a link line, and 3O-3n is a device, such as a host computer.

FIG. 2(A) is a diagram showing an example of a message to be transmitted. FC is a function code, and a code corresponding to the data content and function is attached.

SA is the address (source address) of the NCP that created and sent the message, and rla ta is the information to be processed.

FIG. 3 is an example of the device configuration of NCPOO.

40 is a processing device, 51-54 are interfaces for transmitting and receiving data with the line, 61 and 62 are buffers, 71 and 72 and 91-97 are registers, 81-87 are counters, and 98 is a timer.

In the device of the present invention, all NCPs have the same configuration and function. Therefore, the test of the present invention will be explained below by taking NCPOO as an example.

The present invention detects a transmission path abnormality by counting the number of retransmissions per a certain number of transmitted data and comparing this number of retransmissions with a predetermined value.

(4) When data is transmitted, the transmitted data is sent to the transmit buffer 6.
1 and is transmitted from the interface corresponding to the flag set in the register 71 by the processing device 40.

When the own MCP is the starting point of data on this transmission path (hereinafter, this data is referred to as self-transmitted data), the counter 81 that adds up the number of self-transmitted data is updated, and the time counter 84 is reset. . The time counter 84 is updated by the timer 98, and the processing device 40 updates the time counter 84 by the timer 98.
4, the data cycle waiting time is compared with the contents of the register 96 that defines the data cycle waiting time.

Data received from the line through the interface is
The signal is stored in the reception buffer 62, and a flag identifying the reception line is set in the register 72.

The processing device 40 processes the FC, SA, and register 7 of the received data.
The processing of the received data is determined based on the contents of step 2.

When the self-transmitted data goes around the transmission path within the time specified by the register 96 and is received by the source NCP (5), the processing device 4o determines that the transmission has been performed normally, and stores the data in the transmission buffer. This data stored in 61 will be deleted.

Hereinafter, a case will be described in which data does not return after going around the transmission path within the time specified by the register 96.

The processing bag @40 transmits the data stored in the transmission buffer 61 again. At this time, a counter 83 that counts the number of retransmitted data and a counter 82 that adds up the number of retransmitted data
is updated, and the time counter 84 is reset.

If the retransmitted data goes around the transmission path and returns within the time specified by the register 96, the transmission path is determined to be normal and the counter 83 is reset. If it does not return, retransmission is performed by the retransmission process described above.

The processing device 40 processes 1 depending on the contents of the counters 81 to 83.
If the number of retransmissions exceeds a predetermined value for each piece of data, and if the cumulative number of retransmissions during transmission of a certain number of data exceeds a predetermined value, it is determined that there is an abnormality in the transmission path. The former is a steady abnormality, and the latter (6) is an intermittent abnormality.

A specific determination method will be explained below.

When the contents of the register 83 indicating the number of retransmissions for No. 1 data become equal to the contents of the register 93 specifying the number of retransmissions for one piece of data, the processing device 40
It is determined that there is an abnormality in the transmission path, the counters 8] and 83 are reset, and processing for detouring around the abnormality is started.

When the content of the self-transmission data accumulation counter 81 becomes equal to the content of the register 91 that defines the transmission line abnormality check cycle, the processing device 4o controls the retransmission count accumulation counter 8.
2 and the cumulative number of retransmissions.
If the former value is larger than the latter value, it is determined that there is an intermittent transmission path abnormality, and the counters 81 to 8 are
3 and start the abnormal location detour processing. When it is determined by the counter 82 and the register 92 that the transmission path is normal, the counters 81 to 84 are reset.

Below, a transmission path abnormality is detected by the above judgment (7) We will explain how to bypass the abnormal location in such a case.

When the NCP detects an abnormality in the transmission path, it starts a small loop check. The small loop is a loop indicated by a broken line in FIG.
This is a loop consisting of P.

An example of the small loop check data is shown in FIG. 2(B). F
C is attached with a small loop check code. The address of the NCR that created this data is in the SA, and the address of the NCR that created this data is 1 in the SAO.
The address of the NCP that started the loop check, that is, the NCP that detected the transmission path abnormality, is attached to each address.

The NCR that detected the transmission path abnormality informs the paired NCP,
Send request data to start a small loop check. The paired NCP that receives this request data starts a small loop check.

An NCP that receives the small loop check data transmitted by the upstream neighboring NCP of the loop to which it belongs changes the SA to its own NCP.
Send the small loop check data changed to the CP address to the loop line.

(8) The specific processing is as follows.

(1) The NCP that detected the transmission path abnormality and the paired NCP that received the small loop check request from this NCP are SA,
Both SAO creates small loop check data for its own NCP address and sends it to the loop line.

(2) Processing when small loop check data is received (a) When received from a loop link line, determine the SA, and if it is the own NCP address, update the - loop data count counter 86 and erase this data. . If sA is not the own NCP address, it is sent to the loop line.

(b) When received from a loop line, the SAO is determined, and if it is the own NCP address, this data is deleted.

If the SAO is not the own NCP address, determine the SA. If SA is the address of the paired NCP, send it to the loop link line (9). If the SA is not an NCP address, this data is sent to the loop link line. Further, the content of the counter 85 is checked and if it is 0, the SAO creates small loop check data with SA as its own NCP address without changing it, and sends it to the loop line.

FIG. 4 shows an example of a small loop check when the NCPOO detects a transmission path abnormality. The broken line indicates the flow of small loop check data, and the mark in the circle indicating NCP indicates this NC.
P indicates that the small loop check data has been created.

Dashed line (S, n.

m) indicates small loop check data, S is FC, n
indicates SA and m indicates SAO.

When transmitting small loop check data, the transmission data number counter 85 is updated and the time counter 84 is reset to 1. The counter 84 is updated by a timer 98, and when it becomes equal to the contents of the register 97 defining the transmission cycle, the same small loop check data is transmitted.

When receiving self-transmitted small loop check data, (10) The received data number counter 86 is updated.

When the content of the counter 85 becomes equal to the content of the register 94 that defines the number of small loop checks, the processing device 40 stops transmitting the small loop check data, and after the content of the time counter 84 becomes equal to the content of the register 97, The contents of the counter 86 indicating the number of self-transmitted small loop check data received are compared with the contents of the register 95. If the contents of the counter 86 are greater than the contents of the register 95, it is determined that this small loop is normal. If it is smaller, it is assumed that there is an abnormality in the transmission path, and a detour is constructed to transmit data to the paired NCP through the loop link line.

When the above-described determination process is completed, the counters 84 to 86 are reset.

After completing the small loop check or completing the detour configuration, the NCP resumes normal data transmission and reception.

Below, a method for canceling the detour when the abnormality is restored to normal through repair or the like will be explained.

(11) The NCP that has configured the detour performs a large loop check. In the large loop check, data specified by FC is sent so that data is transmitted only through the loop line, and the loop line is checked by checking whether this data goes around the loop line and returns. be.

The processing device 40 of the NCP that configured the detour resets the time counter 87 and resets the transmission data number counter 85.
and sends the large loop check data to the loop line. The time counter 87 is updated by a timer 98, and the time counter 87 is updated by a register 9 that defines the data transmission line-to-wait time.
The counter 85 is updated each time it becomes equal to the contents of 6.
Large loop check data is sent. When the self-generated large loop check data is received, the counter 86 is updated.

When the content of the counter 85 and the content of the register 94 that defines the number of check data transmissions become equal, the content of the counter 86 and the content of the register 195 that defines the number of received check data are compared. If the content of counter 86 (12) is greater than the content of register 95, it is determined that the loop line is normal, the detour is canceled, and counter 86 is determined to be normal.
5 to 87 are reset. Conversely, if the contents of the counter 86 are smaller than the contents of the register 95, it is determined that the transmission path is abnormal, the detour is not canceled, and the counters 85 to
87 is reset and the large loop check process described above continues.

FIGS. 5(A), (B), and (C) schematically show the present invention.

The broken line shows the small loop check data, the dashed line shows the large loop check data, and the solid line shows the normal data flow.The mark in the circle indicating the NCP indicates that this NCP is the source of the large loop check data. shows. It is assumed that there is an abnormality in the X open position between NCPOI and 02, and the gold mark indicates the loop link line that will be a detour.

If an abnormality occurs in the x position, a small loop check is performed, and NCPOI and 12 are connected to loop link lines 21 and 2, respectively.
2 as a detour (Fig. 5(A)).

(13) NCPOI and 12 that formed the detour perform a large loop check. Since loop line 1 is normal, NCP12
cancels the detour of the loop link line (Figure 5 (B)
). As a result, there are places on the transmission path where the same data passes twice. Also, at this time, in order to return the data to the source NCP, the data must be detoured through the NCP that is a pair of the source NCP (FIG. 5(C)). For this reason, the double reception prevention process and detour process are described in the "Loop Transmission System" (inventors: Mori, Ihara, Matsumaru) filed earlier on July 11th, so their explanation will be omitted.

〔Effect of the invention〕

As described above, according to the present invention, if each NCP only knows its own address and the address of the other NCP, it can detect an abnormality on the transmission path, bypass the abnormal location, transmit data, and When the abnormality is restored to normal, the normal transmission path can be restored. In particular, if abnormalities in the transmission line are due to noise, etc.
Even abnormalities that cause intermittent transmission errors can be detected, and (14) it is possible to prevent repetition of detour configuration and cancellation due to intermittent transmission errors and normal transmission.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the transmission system of the present invention, FIG. 2 is an explanatory diagram showing the configuration of the message of the present invention, FIG. 3 is a block diagram showing the configuration of the NCP of the present invention, and FIGS. 4 and 5 is an explanatory diagram showing the operation of the present invention (15) $/time $2 Figure CA) Mouth [Roro = Mouth 2nd Ko (B) Mouth [4] Go =] $3 times r ---111-- 1--11--1

Claims (1)

[Claims] Two loop lines that transmit data in opposite directions, a transmission control device provided in pairs on the two loop lines, and a loop that transmits data bidirectionally between each pair of transmission control devices. In a double-loop transmission system consisting of a link line, the excess that occurs in the transmission line when test data is transmitted multiple times to a small loop consisting of two adjacent pairs of transmission control devices, the loop line between them, and the loop link line. A transient failure that detects an abnormality, configures a new transmission line that detours around the part of the transmission line where the transient abnormality was detected, transmits data, and switches to the normal transmission line when the transient abnormality area recovers to normal. detection and recovery device.