JPH0918505A - Fault processing method of loop transmission system - Google Patents

Abstract

PURPOSE: To detect a fault occurring to a node other than an object of self- diagnosis and to prevent the fault from extending to the whole by disconnecting the node from a loop transmission line if the frequency of transmission of a beacon within a certain period exceeds a threshold value. CONSTITUTION: In each node, a beacon monitor part 12 is provided. A timer 120 gives timing wherein the count value of a beacon transmission counter 121 is compared with the threshold value previously set in a threshold value comparing circuit 122. Each time the constant time set in this timer 120 is reached, the count value of the beacon transmission counter 121 is compared with the threshold value previously set in the threshold value comparing circuit 122. When the count value is equal to or larger than threshold value, it is judged that a fault that can not be found by a self-diagnostic test of the FDDI standards occurs between this node and upstream node and the threshold value comparing circuit 122 disconnects the node from the loop transmission line as it is.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fault processing method for a loop transmission system in which computer devices such as workstations and personal computers are connected in a loop by a transmission line.

[0002]

2. Description of the Related Art In a loop type transmission system in which computer devices such as workstations and personal computers are connected in a loop by a transmission line, various types of loop transmission systems have been conventionally used so that a failure of one node does not result in the entire loop functioning. It has been devised.

In particular, 1 which is one of the loop transmission systems
FDDI (Fiber Distributed Data Int) of 00 Mbps
erface) LAN (Local Area Network) ANSI
The FDDI standard (ANSIX3T9 / SMT Rev6.2) agreed by the (American National Standards Institute) is used to minimize the failure by the following failure processing method.

FIG. 4 is an overall configuration diagram of a conventional FDDI loop transmission system. A loop transmission line 1 composed of a primary transmission line 1a and a secondary transmission line 2a has a plurality of nodes a2, b3, c4. Are connected in a loop.

The relationship between these nodes is that node c4 is downstream node a2 and upstream node is node b3.
It has become.

[0006] Each node is configured as follows, when the node c4 is described as a representative. That is, optical transmission / reception circuits 5 and 6 for receiving an optical signal from the loop transmission line 1 and transmitting an optical signal to the loop transmission line 1,
An FDDI interface (A) 9 for controlling reception of the primary transmission path 1a and transmission control of the secondary transmission path 1b;
An FDDI interface (B) 10 that controls the transmission of the primary transmission line 1a and the reception control of the secondary transmission line 1b.
And a loop monitoring control unit 11 that performs a failure process defined by the FDDI standard.

Then, the loop monitoring control unit 11 has 14
Is a token reception monitoring timer 110 that monitors the reception timer of the token (Token), a beacon (Beacon)
And a beacon reception monitoring timer 111 for monitoring whether or not the beacon transmitted by the own node returns within a fixed time.

The token (Token) circulates around the loop transmission line 1 at a constant cycle. As shown in FIG. 5A, this token (Token) is composed of a preamble (PA) 51, a start delimiter (SD) 52, a frame control (FC) 53, and an end delimiter (ED) 54. .

The preamble (PA) 51 is a field for synchronization control, the start delimiter (SD) 52 is a field indicating the start of a frame, and the frame control (FC) 53 is "1".
An end delimiter (ED) 54, which is a field indicated by the symbol "0000000", is a field indicating the end of the frame.

The beacon (Beacon) is a control frame transmitted when the token reception monitoring timer 110 times out, and as shown in FIG. 5B, a preamble (PA) 55, a start delimiter (SD) 56, Frame control (FC) 57, destination address (DA) 58,
Source address (SD) 59, information (INFO) 60,
The frame check sequence (FCS) 61, the end delimiter (ED) 62, and the frame state (FS) 63 are included.

A preamble (PA) 55 is a field for synchronization control, a start delimiter (SD) 56 is a field indicating the start of a frame, and a frame control (FC) 57 is "1".
The field indicated by the symbol “0000010” (in the case of beacon), the destination address (DA) 58 is the destination node address, the source address (SD) 59 is the source node address, and the information (INFO) 60 is “00000”.
000 "(in the case of a beacon), a frame check sequence (FCS) 61 is a field for frame error check, an end delimiter (E
D) 62 is a field indicating the end of the frame, and frame state (FS) 63 is a field indicating the frame state.

In this structure, the token reception monitoring timer 110 of each node monitors that a control frame called a token circulates at regular intervals.

When the token does not circulate until the token reception monitoring timer 110 times out, the loop monitoring control unit 11 uses F as a timing trigger.
A beacon is transmitted from the optical transmission / reception circuit 6 to the loop transmission line 1 via the DDI interface (B) 10.

The loop monitoring control unit 11 of the node that has transmitted the beacon, for example, the node c4, can receive the beacon transmitted by the own node via the loop transmission line 1 within the time determined by the beacon reception monitoring timer 111. To monitor.

In this beacon monitoring state, when the beacon reception monitoring timer 111 times out and the beacon is not received, the loop monitoring control unit 11 of the node c4 receives the optical transmission / reception circuit 5 from the optical transmission / reception circuit 5 via the FDDI interface (A) 9. Node b3 located immediately upstream of node c4
In contrast, MLS (Master Line State)
Control frame 7 called.

Further, the FDDI interface (A) 9
After switching the connection between the optical transmission / reception circuit 5 and the optical transmission / reception circuit 5 as shown in FIG. 6 and leaving the loop transmission line 1, a self-diagnosis test is performed to confirm the normality of the own node c4.

The MLS 7 is formed by repeating the signal "0000000100", as shown in FIG. 5 (c).

Similarly, the upstream node b which receives the MLS 7 also switches the connection between the FDDI interface (A) 9 and the optical transmission / reception circuit 5 as shown in FIG. Perform a self-test to confirm the normality of c4.

As a result of the self-diagnosis test, the node which is normal is rejoined to the loop transmission line 1, so that the transmission line is established between the adjacent nodes and rejoined. However, the node in which the abnormality is detected does not rejoin the loop transmission line 1 and remains disconnected.

[0020]

However, in the above self-diagnosis test, the optical transceiver circuits 5 and 6 are excluded from the subject of the self-diagnosis test.
The self-diagnosis test result is determined to be normal even if there is a failure inside the connector or the connector.

Then, after obtaining a normal test result, the procedure for rejoining the loop transmission line 1 is started.

However, if there is a failure in the inside of the optical transmission / reception circuits 5, 6 or the connector, the establishment of the transmission line with the adjacent node fails, and the loop transmission line 1 is used again to execute the self-diagnosis test. break away. That is, due to the failure of the optical transmission / reception circuits 5 and 6 which are not the targets of the self-diagnosis test, the operation of repeating the withdrawal / addition to the loop transmission line 1 continues. As a result, there is a problem that the entire loop transmission system becomes inoperable.

Originally, when there is an abnormality in establishing a transmission path between adjacent nodes at the time of self-diagnosis test and re-joining, the faulty node is disconnected from the loop transmission system to perform a degenerate operation, thereby causing a fault. Can be minimized.

However, if the failure of the optical transmission / reception circuits 5 and 6 is an intermittent failure such as characteristic deterioration or connector connection failure, a self-diagnosis test and establishment of a transmission path between adjacent nodes at the time of re-joining are performed. Since it is not possible to detect the faulty part, the node judges that it is normal and rejoins the loop transmission line 1 without being able to separate the faulty part. Then, after rejoining, the same failure is detected again and the loop transmission line 1
Repeatedly leaving / joining. As a result, the failure of the specific node spreads to the entire loop transmission system, making the entire transmission system inoperable.

An object of the present invention is to detect that a failure has occurred outside the self-diagnosis target, disconnect the node having the failure part from the loop transmission line, and the failure of a specific node spreads to the entire loop transmission system. It is an object of the present invention to provide a failure processing method in a loop transmission system that can prevent the occurrence of the error.

[0026]

In order to achieve the above object, the present invention provides, in each node, a counting means for counting the number of beacon transmissions within a certain period, and the number of beacon transmissions has a threshold value. The feature is that the node is detached from the loop transmission line when the number exceeds the limit.

[0027]

Normally, the failure processing of the loop transmission line is performed by the failure processing method defined by the FDDI standard. However, the threshold value of the number of beacon transmissions that occurs within a certain period in each node is defined in advance for the beacon. If the number of beacon transmissions that occur within a certain period exceeds the threshold, the FD
It is determined that a failure that cannot be found by the DI standard self-diagnosis test has occurred, and the relevant node is removed from the loop transmission line.

As a result, even a fault that cannot be handled by the FDDI standard can be dealt with, and the fault can be minimized.

At the node located immediately upstream of the faulty node, the optical transmission / reception circuit of the faulty node is disconnected so that F
Since the DDI interface A detects the optical signal loss, F
By performing the return operation with the DDI interface A, the degenerate operation in which the faulty part is separated from the loop transmission line is performed.

As a result, it is possible to prevent the failure of the specific node from spreading to the entire loop transmission system. In particular, it is extremely effective against failures that occur intermittently, such as defective characteristics of circuit elements and defective connections of connectors.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an illustrated embodiment.

FIG. 1 is a system configuration diagram showing an embodiment of a loop transmission system to which the present invention is applied. In addition to the conventional configuration of FIG. 4, a beacon monitoring unit 12 is newly provided in each node. Is.

The beacon monitoring unit 12 includes a timer 12
0, beacon transmission counter 121, threshold comparison circuit 1
22.

The other parts have the same structure as that shown in FIG.

The timer 120 is a beacon transmission counter 1
21 is provided to give a timing for comparing the count value of 21 with a threshold value set in advance in the threshold value comparison circuit 122, and the count of the beacon transmission counter 121 is counted every time the fixed period set in the timer 120 expires. The value is compared with a preset threshold value in the threshold value comparison circuit 122, and when the count value is equal to or greater than the threshold value, a failure not found by the self-diagnosis test of the FDDI standard occurs between the own node and the upstream node. The threshold value comparison circuit 122 disconnects the node from the loop transmission line.

Here, the beacon transmission counter 121 is
The timer 120 is cleared every two fixed periods.

The count value is updated by "1" every time one beacon having the frame structure shown in FIG. 5B is transmitted.

FIG. 2 is a flow chart showing the loop monitoring control procedure of each node in this embodiment. First, it is judged whether or not the token reception monitoring timer 110 has timed out (step S10). Interface (B) to optical transmitter / receiver circuit 6
Is used to transmit a beacon to the loop transmission path (step S11). After that, after counting up the beacon transmission count value of the beacon transmission counter 121,
The count value is compared with the threshold value set in the threshold value comparison circuit 122 (step S14), and the count value ≧
In the case of the threshold value, it is determined that a failure not found by the self-diagnosis test of the FDDI standard has occurred between the self-node and the upstream node, and the FDDI interface (A) 9 receives the optical transmission / reception circuit 5 The disconnection command is issued (step S16).

For example, assuming that there is a failure inside the optical transmission / reception circuit 6 of the node b3, the node c4 on the downstream side of the node b3 is, as shown in FIG.
Is operated at the portion of the FDDI interface (A) 9 by folding back and contracting.

Then, by disconnecting the optical transmission / reception circuit 5 of the node c4, the node b located upstream of the node c4.
The FDDI interface (A) 9 of No. 3 detects an optical signal break (step S16), disconnects the optical transmission / reception circuit 6 from the FDDI interface (A) as shown in FIG. The operation is performed to disconnect the faulty part from the loop transmission line 1 to minimize the fault.

On the other hand, as a result of comparison with the threshold value, if the beacon transmission count counter value is less than or equal to the threshold value, F
When the fault processing of the loop transmission line 1 defined by the DDI standard is performed and the beacon reception monitoring timer 111 times out (step S20), the optical transmission / reception circuit 5 is used to perform F
The MDI 7 is transmitted from the DDI interface (A) 9 to the node b2 located immediately upstream of the node c4 (step S21). Then, the loop transmission line 1 is disconnected, and a self-diagnosis test is performed to confirm the normality of the circuit of the own node (step S22).

Similarly, the node b3 which received the MLS7 also leaves the loop transmission line 1 and performs a self-diagnosis test to confirm the normality of the circuit of its own node. When rejoining the transmission line and detecting an abnormality, the loop transmission line is left and the loop transmission line is not rejoined (steps S23 to S25).

On the other hand, after disconnecting the faulty part due to the threshold value of the number of beacon transmissions being exceeded, FD is applied at node c4.
The address information (MAC address information) regularly exchanged between the adjacent nodes defined by the DI standard is monitored (step S17), and the node address different from the upstream node address at the time of disconnection is notified from the upstream node when the repair of the node b3 is completed. In the case of the release, a disconnection release command is issued to the FDDI interface (A) 9 of the node c4,
The turn-back operation in the FDDI interface (A) 9 is canceled (steps S18 and S19).

Then, the FDDI interface (A) 9 of the node b3 detects the optical signal and cancels the return operation at the FDDI interface (A) 9. This allows
The transmission path between the node node b3 and the node c4 is restored.

[0045]

As described above, according to the present invention, in addition to the failure processing function defined by the standard of the loop transmission system, even when a failure mode that cannot be detected by the standard occurs, each node is By monitoring the number of beacon transmissions sent within a unit period, it is possible to disconnect from the loop transmission line, prevent the failure of a specific node from spreading to the entire loop transmission system, and maintain the integrity of the loop transmission system. It becomes possible.

In particular, the present invention is extremely effective against intermittent failures such as defective characteristics of circuit elements and defective connections of connectors.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a loop monitoring control operation in the embodiment.

FIG. 3 is a system configuration diagram showing a state in which a faulty part is separated in the embodiment.

FIG. 4 is a system configuration diagram of a conventional loop transmission system.

FIG. 5 is a frame configuration diagram of a token and a beacon.

FIG. 6 is a system configuration diagram showing a state in which a faulty part is separated in a conventional loop transmission system.

[Explanation of symbols]

1 ... Loop transmission line, 2 ... Node a, 3 ... Node b, 4 ...
Nodes c, 5, 6 ... Optical transceiver circuit, 7 ... MLS, 9 ... F
DDI interface (A), 10 ... FDDI interface (B), 11 ... Loop monitoring control unit, 12 ... Beacon monitoring unit, 110 ... Token reception monitoring timer, 111 ...
Beacon reception monitoring timer, 120 ... Timer, 121 ... Beacon transmission counter, 122 ... Threshold comparison circuit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Wada 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Prefecture Hitachi Systems, Ltd. Office Systems Division (72) Inventor Shinichi Mizoguchi 2-6-1 Otemachi, Chiyoda-ku, Tokyo Within Hitachi Information Network Co., Ltd.

Claims (3)

[Claims] 1. In a loop transmission system comprising a plurality of communication nodes connected in a loop by a transmission line, the number of times of transmission of a fault detection beacon in each communication node is counted and A failure processing method in a loop transmission system, comprising: comparing with a preset threshold value; if the count value reaches a threshold value or more, disconnecting the communication node from the transmission path. 2. When the count value is less than a threshold value,
2. The fault processing method in a loop transmission system according to claim 1, wherein self-diagnosis is performed after transmitting a specific signal to the upstream communication node. 3. The node address of the upstream communication node is monitored after leaving the transmission line, and if the node address different from that before the leaving is notified, the node is rejoined to the transmission line. Or a fault processing method in the loop transmission system according to 2.