JP2739532B2 - Reconfiguration control method for token ring LAN system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an IEEE (The I
nstate of Electric and
Electronics Engineers) 80
2.5 Token Ring LAN (Local A
FCS that detects a failure such as a one-line disconnection or a half-line disconnection and automatically disconnects the failure part and releases the failure after the failure recovery in the network
(Frame Check Sequence) The present invention relates to a reconfiguration control method based on error rate monitoring.

[0002]

2. Description of the Related Art Conventionally, a plurality of terminals share a LAN transmission path. However, in order to avoid a collision between a frame transmitted by one terminal and a frame transmitted by another terminal, a medium is used. Access control (MAC: Media Acc)
Ess Control) controls the transmission right. In the case of a LAN, a frame for performing the medium access control and a logical link control (LLC: Log
ic Link Control). Among the various methods of the medium access control, there is a token ring system having a high throughput of a communication amount. FIG. 4 shows a configuration of a token ring type network.

In FIG. 4, reference numerals 1A to 1D denote communication terminal devices using a LAN transmission line, 2A to 2D denote configuration control devices for accommodating the communication terminal devices 1A to 1D, and 3 and 4 denote transmission lines having a double structure. There are a first ring transmission line and a second ring transmission line. In the first and second ring transmission lines (hereinafter, simply referred to as rings) 3, 4, frames of a transmission right (hereinafter, referred to as a token) are circulated. The transmitting communication terminal device captures the circulating frame,
A necessary frame such as a destination address or a source address is added and transmitted.

On the other hand, a receiving communication terminal device always monitors a frame circulating on a transmission line, takes in a frame addressed to itself, and copies the original frame around a ring. When the frame transmitted by the communication terminal device returns, the transmitting communication terminal device removes the frame from the ring and circulates the token, that is, the transmission right. Therefore, in the token ring system, each communication terminal device can obtain a transmission right equally.

In such a token ring system,
Conditions for removing a failure by detecting a communication failure and performing an automatic reconfiguration operation and monitoring a failure recovery method are performed under the following conditions.

First, failure detection methods include: (a) that a transmission right (token) circulating on a transmission path specified by a protocol has disappeared, that is, that it does not circulate; This is a method of detecting each condition of continuing for 32 ms.

[0007] The failure recovery monitoring method for determining whether or not the failure has recovered is as follows: (a) Appearance (tour) of a token (b) Successful re-joining to the ring. This is a method of monitoring the conditions.

[0008]

However, in the conventional reconfiguration control method, in the failure detection method, a twisted pair line (a cable used for a transmission line in a token ring LAN system conforming to IEEE802.5) is used for the transmission line. In such a case, it is possible to detect a failure due to a double-wire break of the twisted pair wire, a short-circuit between both wires, and an abnormality in communication control, but it is difficult to detect a single-wire break and a half-wire break.

[0009] Further, when the fault recovery monitoring is performed by the conventional method, when both of the twisted pair wires are disconnected, both wires are short-circuited, and
Although it is possible to recognize the recovery from a fault that has been removed due to an error in the communication control unit, the fault that has been removed due to a one- or half-broken fault (intermittent fault) is notwithstanding the fault. In some cases, it may be erroneously determined that the failure recovery has been completed.

As described above, the conventional fault detection and recovery detection methods have a low fault detection rate when a fault occurs due to a one-wire break or a half-break. The problem is that it is recognized as failure recovery.

The present invention has been made to solve such a problem, and an improvement in the detection rate of a one-wire disconnection or a partial disconnection fault has been achieved.
Token ring LAN that can prevent false failure recovery monitoring
An object of the present invention is to provide a system reconfiguration control method.

[0012]

In order to achieve the above object, a reconfiguration control method for a token ring LAN system according to the present invention provides a method for controlling the total number of frames circulating in a ring and a frame check sequence of the frames (hereinafter, referred to as a frame check sequence). (Referred to as FCS) is constantly monitored, and when the number of frames causing an FCS error reaches a predetermined ratio of the entire frame, it is determined that a failure has occurred in the transmission path, and the ring is automatically turned back. Eliminate points of failure. And
After the removal of the fault point, the ring state on the fault side is restored by sending the LLC frame multiple times, collating the LLC frame received cyclically with the sent LLC frame, and automatically checking if all the matching results match. In this case, the ring wrap is released.

[0013]

[Action] constantly monitors the frame being circulated on the ring, and calculates the sum of the total number of frames, the ratio by summation of the frame F CS unit abnormality. When this ratio exceeds a predetermined value, it can be determined that an intermittent failure (one-line disconnection, half-disconnection, etc.) has occurred, and the detection rate is improved.

After the fault point is removed due to an intermittent fault, restoration of the ring state on the fault side is performed by a LLC of several kilobytes.
By transmitting the frame, the transmission path of the ring on the failure side is covered with the LLC frame. At this time, if an intermittent one-line disconnection or half-disconnection failure occurs, L
If the data of the LC frame is destroyed and it is determined that the failure has not been recovered yet, erroneous recovery from the failure can be prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A reconfiguration control method for a token ring LAN system according to the present invention will be described below with reference to the drawings. FIG.
Indicates a state from the detection of a failure to the action taken when a failure occurs. In FIG. 1, the same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. However, the first ring 3 and the second ring 4 are shown as linear structures for the sake of illustration, but actually have the same ring structure as FIG. 5A-5D and 7A-
7D indicates a configuration control unit, and 6A to 6D and 8A to 8D indicate communication units. It should be noted that the direction in which the frames are circulated is that 2A, 2B, 2C, 2D
And on the second ring 4 in the opposite direction.

First, in FIG. 1A, it is assumed that a one-line break or an intermittent half-break occurs at a point 9 on the first ring 3 between the configuration controllers 2B and 2C.

If normal communication is performed in this state, an intermittent abnormality (unsuccess) occurs in the frame transmitter for communication. Therefore, each of the configuration controllers 2A to 2D constantly monitors the frames circulating on the rings 3 and 4, but monitors the frames circulating on the first ring 3 by the configuration controller 5A.
Or 5D. The configuration control units 5A to 5D
Of the frames circulating on the ring 3 of the above, the frames with the FCS failure are counted. FIG. 4 shows the FCS at this time.
9 is a flowchart illustrating a routine of an error rate monitoring procedure. In FIG. 4, when the FCS error rate monitoring program starts, first, in step S1,
Set the number of frames to be checked for FCS error. In the next step S2, the FCS error counter is cleared. Then, in step S3, monitoring of the FCS error frame and the received frame is started, and in step S4
Then, it is determined whether or not the number of FCS error check target frames has reached a set value. If it is determined that the number has reached the set number, the process proceeds to step S5, and monitoring of the FCS error frame and the received frame is started.

In step S6, the contents of the FCS error counter are read, and in step S7, it is determined whether the ratio between the number of FCS error check target frames and the number of FCS error frames has exceeded a set value. If it is determined that the value does not exceed the set value, the process returns to step S1. If the value exceeds the set value, the FCS error rate monitoring routine ends.

When the configuration controllers 2A to 2D determine that the ratio of the sum of the frames circulating on the ring 3 to the sum of the received FCS bad frames exceeds a set value, it determines which one of the transmission paths Recognize that a crab failure has occurred. Then, each of the configuration control devices 2A to 2D respectively controls the long beacon MAC frame (IEEE80
A MAC frame specified in 2.5 with several kilobytes of data added) is transmitted to the configuration control units 5A to 5D .

[0020] In this case, as it is clear from FIG. 1 (a), since it occurs intermittently faulty location 9 on the first ring between configuration control device 2B and 2C, configuration controller 2
A is a long beacon MAC frame from the configuration control unit 5D.
The configuration control device 2B transmits the long
The configuration control device 2D controls the beacon MAC frame
Receiving the long beacon MAC frame from the control unit 5C
Then, transmission of the long beacon MAC frame is stopped, and the apparatus enters a reconfiguration waiting state. In addition, the configuration system immediately downstream of the fault point 9
The control device 2C is a long beeco transmitted from the configuration control unit 5B.
MAC frame has not been received and the long beacon MA
This will continue to transmit C frames,
Identify the configuration control device immediately downstream of the point of harm.

[0021] In FIG. 1 (b), the configuration controller 2 C immediately downstream of the point of failure, or failure of the failure that has occurred is on the first ring 3, to isolate or failures on the branch of the communication terminal device 1C In addition, the internal transmission line 11 including only the configuration control device 2C is configured to transmit the long beacon MAC frame to the configuration control unit 5C.
Send more. As a result, the long beacon MAC frame makes a round in the internal transmission path 11, so that the occurrence of the failure is recognized as a failure on the first ring 3. Next, after returning the internal transmission line 11 to the normal state , a pseudo failure (simulated transmission line disconnection state) is generated on the location 10 of the second ring 4 using the configuration control unit 7C.

Along with the occurrence of the above-mentioned pseudo fault location, the configuration controller 2B immediately upstream of the fault point detects a fault in the second ring 4, and as shown in FIG. The first ring 3 and the second ring 4 are connected to form a folded transmission path 12. This return transmission line 12
Accordingly, the long beacon MAC frame 13 flows from the first ring 3 to the second ring 4.

On the other hand, the other configuration controllers 2A and 2D enter the ring recovery wait state when the configuration controllers 7A and 7D of the second ring 4 receive the long beacon MAC frame 13.

The configuration control device 2C transmits the long beacon MA of its own transmission which is turned back by the configuration control device 2B.
The C frame 13 is received by the configuration controller 7C of the second ring 4, and as shown in FIG.
To form a folded transmission path 14. At this time, the pseudo failure 10 is removed, and the transmission of the long beacon MAC frame 13 is stopped.

Therefore, a transmission path of a double ring configuration avoiding the failure point 9, that is, a transmission path loop excluding the failure point 9 is formed by the two folded transmission paths 12 and 14, so that the ordinary token ring system is used. The LAN system will be reconfigured. At the same time, the configuration control device 2
A transmission path loop 15 including the failure point 9 and the configuration controllers 7B and 7C is formed between B and 2C, and is used for monitoring failure recovery described later.

Next, a fault recovery monitoring method will be described with reference to FIG. In FIG. 2A, in the transmission line loop 15 including the failure point 9 between the configuration control devices 2B and 2C, the token circulation is monitored by the configuration control units 7B and 7C. When the token circulation is detected, the configuration controllers 2B and 2C transmit and receive LLC frames by the communication units 8B and 8C. When the configuration control devices 2B and 2C receive the LLC frame normally a predetermined number of times, they recognize that the failure has been recovered, release the loopback transmission lines 12 and 14, and the transmission line loop 15, and change the ring as shown in FIG. Return to the original state as shown in b).

As described above, in the present embodiment, in the conventional token ring LAN system, intermittent trouble spots such as a broken wire or a broken wire which could not be detected as a fault can be reliably detected. , By automatically isolating the obstacle, the token ring L
The communication quality of the AN system can be improved. Further, when monitoring the failure recovery, by using the LLC frame, erroneous recovery can be prevented, and the reliability of communication can be improved.

[0028]

As is clear from the above embodiment, the present invention constantly monitors the number of frames circulating in the ring and the quality of the frame check sequence in the frame, and determines whether or not the frame has a frame check sequence error. Is determined to be a transmission line failure when the ratio of all frames has been determined, and automatically returns to both sides of the ring failure point to remove the failure point, so it is used as a transmission path in the token ring LAN system. In the IEEE802.5 protocol for twisted pair wires, intermittent faults such as single-wire breaks and half-breaks that could not be completely detected as faults can be detected, and the fault location is automatically separated. This has the effect of improving the communication quality of the token ring LAN system.

After the failure point is removed, the restoration of the ring state on the failure side is monitored by transmitting and receiving LLC frames, and when the number of normal receptions reaches a predetermined ratio, ring return is automatically canceled. As a result, an erroneous recovery can be prevented, and the reliability of communication can be improved.

[Brief description of the drawings]

FIGS. 1A to 1D are explanatory diagrams showing a state of a reconfiguration operation from failure detection to failure point removal in the present embodiment.

FIG. 2 is an explanatory diagram showing a state of a reconfiguration operation at the time of failure recovery in the embodiment.

FIG. 3 is a flowchart illustrating an FCS error rate monitoring procedure in the embodiment.

FIG. 4 is a token ring LAN showing one embodiment of the present invention.
It is a block diagram of a system.

[Explanation of symbols]

 1A to 1D Communication terminal equipment 2A to 2D Configuration control device 3 First ring 4 Second ring 5A to 5D, 7A to 7D Configuration control unit 6A to 6D, 8A to 8D Communication unit 9 Failure point 10 Pseudo failure point 11 Internal Transmission path 12, 14 Return transmission path 13 Long beacon MAC frame 15 Transmission path loop including failure point

Claims (1)

(57) [Claims] 1. A token ring L comprising: a plurality of configuration controllers each accommodating a communication terminal device; and a ring connecting each of said configuration controllers in a ring with a double transmission line.
A configuration control method when a failure occurs in an AN system, wherein each of the configuration control devices includes a number of frames of a logical link control and a medium access control circulating through the ring, and a frame check sequence in the frame. monitoring the quality, when the frame as a frame check sequence error has reached the proportion of the determination of the entire frame, the failure detection frame obtained by adding a predetermined amount of data in the frame transmitted from each of the configuration controller the handicapped
A failure point is detected based on the state of reception or non-reception of the harm detection frame , and a transmission line loop excluding the failure point and a transmission including the failure point are formed in the configuration control device adjacent to the detected failure point to form a return transmission path A token loop LAN system by forming a path loop and circulating the frame through a transmission path loop excluding the failure point, and including the failure point from one of the adjacent configuration control apparatuses to the other. The frame of the logical link control is transmitted through a transmission line loop, and when the other configuration control device receives the normal frame of the logical link control a predetermined number of times, the loopback transmission line is released and the original double A reconfiguration control method for a token ring LAN system, wherein a transmission path is restored.