JPH0720121B2 - How to detect a fault in a ring network - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transmission line reconfiguration method for a ring network, and in particular, a transmission station is bypassed by an optical switch and exceeds a specified section loss, and the transmission line is not connected. The present invention relates to a transmission line reconfiguration method suitable for disconnecting a relevant part from a system or recoupling to the system when it becomes stable.

[Conventional technology]

A conventional transmission line reconfiguration method in a ring network is discussed in Nikkei Electronics, 12.5 (1983), pp. 173 to 199, "100 Mbit / sec ring optical local network connecting bus network". As described above, when a transmission failure occurs, the master station sends a failure search command to each transmission station, recognizes a failed adjacent station, and instructs the station to shift the loop back.

Further, when a failure such that the network becomes unstable due to continuous bypass or the like occurs, the master station searches each station for a failure, and each transmission station makes a judgment as to whether or not the failure is adjacent.
After recognizing a faulty adjacent station, the station loops back in response to a loop back command addressed to itself.

[Problems to be solved by the invention]

In the above-mentioned conventional technique, the transmission station is bypassed by the optical switch to exceed the specified section loss, and the transmission line becomes unstable, that is, the bit error rate increases more than the specified value, or it changes greatly due to changes in the surrounding environment. In the case of a faulty neighboring station search in such a state, sufficient consideration has not been given to speedup, and if there is a large number of transmission stations because it is a reliable type that searches for a faulty neighboring station one by one There was a problem that it took a lot of time to do.

An object of the present invention is to detect a faulty adjacent station at high speed even if the number of transmission stations is large.

[Means for solving problems]

1) Means for the master station to store the connection order of each transmission station in the network.

2) The master station stores the allowable number of continuous bypasses between each station,
A means for sending a search command to the adjacent station with a failure.

3) Means for assigning its own address to the contents of the monitor signal transmitted by each transmission station in response to the search command.

4) A means for shifting the addresses of a plurality of stations in the supervisory signal received from each station to the self-transmitted supervisory signal.

5) Means for relaying the supervisory signal received from the upstream by the station receiving the path command.

6) Compare the received supervisory signal with the connection order from 1) above,
2) A means for judging the presence or absence of a faulty adjacent station by judging continuous bypass from the above.

It is achieved by providing.

[Action]

When a transmission failure occurs in the network, the master station issues a simultaneous failure search command to each transmission station. Receiving this, each transmission station sends out a supervisory signal containing its own address and stores the supervisory signals of a plurality of stations received from the upstream side. At this time, if the master station receives the supervisory signal from the upstream, it sends a path command to a plurality of stations and recognizes the addresses of the plurality of stations.

To determine whether or not the mask station should loop back, first calculate the number of relay stages from the transmission station connection order table, which stores the addresses of multiple stations in the received supervisory signal in order, to the sending station of the current adjacent station. Similarly, is executed by comparing with the number of allowable bypass stages stored in advance, and an illegal bypass point in the network is detected at high speed.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

FIG. 2 is an example of the overall configuration of a ring-shaped local network system having a double ring transmission line including a transmission device to which the present invention is applied. Various information terminal devices 1a~Nc interspersed flight various locations as shown in the ring transmission lines O _a by via a transmission device 1~N example fiber optic is connected to O _b, to form a whole as a single ring network , Performs mutual communication between arbitrary terminal devices.

This kind of network functions as the nervous system of the system, and its importance is increasing as information processing progresses.
However, while each information terminal equipment can share a single transmission path at high speed, it has the characteristic that the influence of a transmission failure can easily spread. In order to improve the reliability of the network, methods such as bypass and loop back are well known in the above ring network. Since each method has different effectiveness depending on the type of obstacle, it is preferable to have both of them, rather than using them individually if possible.

The present invention is applied to such a highly reliable ring local network.

FIG. 1 shows an example of a hardware block when the present invention is applied to a transmission device for a dual ring network. Here, the transmission device N represents its configuration by representing each of the transmission devices 1 to N in the system shown in FIG. 2, and roughly comprises the following five functional blocks.

The bypass means 10 is realized by two sets of optical switches corresponding to the transmission lines O _a and O _b , and is used for disconnecting from the transmission line when a failure occurs in this transmission device. Although the operation control line to the switch is not drawn, it is activated by bypass due to the well-known power interruption, hardware failure, or manual operation by a manual switch.

The route switching means 20 is provided to switch the passage route of the information received from the transmission line in the transmission device and the transmission source of the transmission information, and normally only one is used for communication between the terminal devices. , The other one should be put on standby as a spare. Specifically, receivers 21 and 25 having functions of optical / electrical conversion, retiming, demodulation, transmitters 22 and 26 having functions of modulation and electric / optical modulation, and two transmission multiplexers 23 and 27, And a receiving multiplexer 24. The instruction to select each multiplexer is made possible by the constituent means 40 described later.

The information transmission means 30 is used for information transfer between the configuration control means across the transmission devices, and is composed of command storage sections 31, 33 and command generation sections 32, 34 corresponding to a set of transmission paths. These are configured so that the information of the transmission format described in FIG. 3 can be transferred to and from the configuration control means 40, and are mainly realized by a FIFO (First In First Out) register.

The configuration control means 40 cooperates with the same means of other transmission devices to detect the occurrence and / or recovery of a fault in the transmission network, and to enable transmission and / or recapture of these points from the network. Executes control of the road configuration. Main components are microprocessor 41, memory 42 and microcomputer bus
It is 43 mag. The selection instruction to the route switching means 20 and the passing of information between the information transmitting means 30 are performed by the microprocessor 41.
Via the microcomputer bus 43.

The access control means 50 is a terminal device connected to this transmission device.
N _{a to} N _N are provided for executing data transmission / reception. A transmission frame control unit 55 that performs transmission frame generation and timing control centering on the transmission bus 54, and is installed in each terminal. It is composed of terminal access control units 51 to 53 having access control and terminal interface functions.

The signal received from the transmission path is output to the transmission bus 54 via the receivers 21 and 25, the reception multiplexer 24, and the transmission frame control unit 55, and is supplied to each terminal access control unit 51 to 53.
Then, this information or transmission information from the terminal access control unit is transmitted from the transmission bus 54 to each transmission multiplexer 23, 27,
It is transmitted again to the transmission path via the transmitters 22 and 26.

On the other hand, the received information from the receivers 21 and 25 is the command storage unit 3 respectively.
It is also provided to 1, 33 and can be recognized by the quichro processor 41 via the microcomputer bus 43. Conversely, the configuration control command from the microprocessor 41 is the microcomputer bus 43.
The pattern is set via the command generators 32 and 34 and repeatedly transmitted from there. Each transmission multiplexer selects one of the command generator, the transmission bus, and the three inputs from the receiver. Which of these is selected according to each state and what kind of connection form will be described later.

FIG. 3 shows a transmission format of information transmitted and received between the configuration control means via the information transmission means. There are four types of this information from types A to D shown in the figure, and the synchronization pattern SY
It is a fixed length of N or less. This information includes an address DA of the other destination transmission device, an address SA of the transmission device of the transmission source, and other sub information SUB. Command storage unit 31, 33
Then, after detecting the sync pattern SYN, the number of bytes for this information length is stored. In this figure, the inspection information for the transmission error check is omitted.

FIG. 4 shows a memory map of the storage unit 42 in the configuration control means. Three types of information required for configuration control are stored here.

1) Self-transmission device address (MSA) 2) Connection order address table (SAO) of intra-network transmission device 3) Maximum allowable bypass stage number table (ABY, BBY) between self-transmission device and upstream transmission device Is determined and stored when the system is set. Regarding 3), two types of transmission lines are provided because the transmission lines in the opposite direction form a pair. Further, for simplification, a commonly used means is to set the maximum allowable number of bypass stages to 1 in all sections, in which case the table of 3) can be omitted. This means that optical bypass of one stage is permitted, but continuous bypass points of two or more stages are not permitted.

Regarding 2), it is possible that not all transmission devices have this but only the master station has it.

FIG. 5 is a list of route types that the route switching means 20 can take. The usage of each type and the selectors at that time, the selection input set of the A system transmission selector 23, the B system transmission selector 27, and the reception selector 24 are as follows.

<Type 1> A system transmission, B system path (1,2,1) <Type 2> B system transmission, A system path (2,1,0) <Type 3> BA loop back (0,1,1) < Type 4> AB loop back (1,0,0) <Type 5> Both system transmission (0,0, X) <Type 6> A system transmission, B system transmission (1,0,1) <Type 7> B system Transmission, A-system transmission (0,1,0) In transmission and loopback, the reception information is supplied from the reception selector 24 to the transmission bus 54 through the transmission frame control unit 55, and transmission is command generation. It shows information transmission from the department.

The operation of each device and each unit when a failure occurs in the network will be described below with reference to the drawings.

FIG. 6 shows the processing flow in the master, and FIGS. 7 and 8 show the processing flow in the slave.

The master, which has detected a failure in both systems of the transmission path, is in a state (type 5) of sending a failure adjacent station search command (command A) from both systems.

Each slave receiving this is in a state (type 6 or type 7) of transmitting the search supervisory signal (command B) from the transmission path on the side opposite to the one receiving the command.

After that, the above-mentioned monitoring signal is detected by the masker, and in the case of normal reception, it becomes a state (type 1 or 2) in which a path command (command C) is sent out. In response to the received address, a check is made to see if there is a fault between multiple stations and the fault location is detected.

The master sequentially monitors the two transmission lines, but the results can be understood in four ways shown in FIG.

B) In both cases, the supervisory signal is not received, or the number of bypass stages exceeds the regulation even if it is received. At this time, the current search state is continued until the failure is recovered.

B) A case where a normal monitoring signal is received only from the A system. In this case, the master itself must be the loop back end.
A path command (command C) is sent from the B system to a plurality of transmission devices for sending the supervisory signal at a time, and the addresses of a plurality of stations of the supervisory signal received thereby are sequentially checked. If there is no obstacle, or in the same way, check between the next stations. As a result, when the fault location is finally found, a loop back shift command (command D) is sent to complete the isolation of the fault location, and finally the transmission mode is changed to type 3 to restart the transmission.

C) A case where a normal monitoring signal is received only from the B system. A
A path command (command C) is sent from the system to a plurality of stations to a plurality of transmission devices for sending a supervisory signal, and the same technology is advanced for the section after that. As a result, when a fault location is finally detected, a loop back shift command (command D) is sent to the transmission apparatus adjacent to the fault to complete the network configuration. Thereafter, the type 4 transmission mode is entered and the transmission is restarted.

D) A case where both systems receive normal monitoring signals.

Use the same procedure as in b) and c) to make loop backs on each side,
After that, transfer to the type 1 configuration form and restart the transmission.

Even in the slave, the results are divided into four ways shown in FIGS. 7 and 8.

A) When the monitoring signal (command B) is sent to the B system (the command is received from the A system) and the loop back shift command (command D) does not reach its own device, the system returns to the type 1 configuration form. . Incidentally, as the return timing, there is a case where the completion of the network configuration operation by the master is detected in addition to the case where the loop back shift command directed to another transmission device is received.

B) When a loop back shift command (command D) is sent from the master station to its own device after sending the monitoring signal to the B system. The system shifts to the type 3 loop back configuration and waits for the restart of transmission.

C) When the supervisory signal (command B) is sent to the A system but the loop back shift command does not reach its own device,
It returns to the type 2 configuration state and waits for the restart of transmission.

D) When the master device receives a loop back shift command (command D) from the master after sending the supervisory signal (command B) to the A system, shifts to the type 4 loop back configuration mode and restarts transmission. wait.

The operation of each transmission device in the network according to the control method described above will be described below.

FIG. 9 corresponds to the transmission of the search command (command A) in FIG. 6, and in the figure, when ST ₁ is operating as the master, the search command T _a is issued to the line O _a this time. Due to a fault between ST and ST ₅ , this signal can only reach ST ₅ 5. In ST _{2 to} ST ₅ , transmission of each supervisory signal is started to O _b opposite to the line that received it. Each of the stations ST _{2 to} ST ₅ changes the content of the received supervisory signal to the supervisory signal transmitted by itself.

Figure 10 shows the contents of the supervisory signals issued by each station. Times of Day
At t ₁ , immediately after receiving the command from the master, the supervisory signal from the upstream is not received, and only the information including its own address of each station is issued. As it goes to t ₂ and t ₃ , the signal from the upstream station comes to be received, so the contents increase the addresses of the SUB area as shown in the figure.

For example, at ST ₂ at time t ₃ , a monitoring signal including the information of ST ₄ as a SUB address is received from the upstream ST _3, so that the monitoring signal transmitted by itself is transmitted with the contents ST ₃ and ST ₄ added. ST ₃ is from the SA area and ST ₄ is from the SUB area.

As a result, it can be seen that at the end, the contents as shown at the time t ₄ are reached. The master station receiving the supervisory signal from ST ₂ knows that its contents indicate the connection order of the ST that is currently active.

In this example, the address table is compared with that of the master station. Furthermore, it turns out that there is no upstream of ST ₅ . Follow go-between in this case must be Rupubatsuku in ST _5. The master station issues a path command to ST ₂ to ST ₅ because it has not yet found the point to loop back. After that, issue a loop back command to ST ₅ to set the loop back configuration. Loop back in the same way in the opposite direction.

Next, in Fig. 9, the case where ST ₃ and ST ₄ are bypassed and the specified number of continuous bypasses is exceeded will be explained. in this case
ST ₂ may receive the supervisory signal from ST ₅ . However, the master station must loop ST ₂ back.

The results are shown in Fig. 11. In this figure, the monitoring signal from ST ₂ received by the master station shows the time t ₄
Even in, there is only ST _{5 in the} SUB information area. As a result, you can see that the station between ST _{2 and} ST ₅ is bypassed. Then, after sending a pass command to ST ₂ , a loop back command can be issued.

The above has described the case where the transmission device is continuously bypassed in multiple stages to disconnect from the system a faulty portion that makes the transmission in that section unstable. It can also be applied when returning to the system again when the fault at the separated location is recovered. When the bypass of a transmission device that has been put out of the network is restored, the transmission device transmits information including its own address, and the loop back terminal station that receives this information or the master notified to that effect by the loop back terminal station. The device detects and determines the same allowable number of bypass stages as described above.

〔The invention's effect〕

According to the present invention, the addresses of a plurality of stations can be recognized at one time, which has the effect of speeding up fault location detection in a dual ring network.

[Brief description of drawings]

FIG. 1 is a hardware block diagram of a ring network transmission device according to an embodiment of the present invention, FIG. 2 is a system configuration diagram of a ring-shaped local network, FIG. 3 is a transmission format diagram between information transmission means, and FIG. FIG. 5 is a memory map diagram of the storage unit in the configuration control means, FIG. 5 is a route type diagram that the route switching means can take, FIG. 6 is an execution flow chart of the master configuration control means, and FIGS. Execution flow chart of configuration control means, FIG. 9 is an explanatory diagram of network configuration operation, FIG. 10, FIG.
FIG. 11 is a transition diagram of supervisory signals in network configuration. O _a , O _b …… Ring transmission line, 1-N …… Transmission device, 1 _a 〜Nc
Terminal equipment, 10 …… Bypass means, 20 …… Route switching means,
30 ... Information transmission means, 40 ... Configuration control means, 50 ... Access control means, 21,25 ... Receiver, 22,26 ... Transmitter, 2
3,24,27 …… Multiplexer, 31,33 …… Command storage section, 32,34 …… Command generation section, 41 …… Microprocessor, 42 …… Memory, 43 …… Microcomputer bus, 51,52,53 …
… Terminal access controller, 54 …… Transmission bus, 55 …… Transmission frame controller.

Front page continuation (72) Inventor ▲ Taka ▼ Masahiro Hashi 4026 Kujimachi, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Ken Onuki 52-1 Omikacho, Hitachi City, Ibaraki Prefecture Ceremony Company Hitachi Ltd. Omika Factory (72) Inventor Toshihiko Uchiyama 52-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Process Computer Engineering Co., Ltd.

Claims (2)

[Claims] 1. A plurality of transmission devices, a terminal device connected to each of the transmission devices, and a dual ring transmission line that connects the transmission devices in a ring shape. In a ring network that communicates with each other via a transmission device, the transmission device includes bypass means for bypassing the ring transmission line from the transmission device, and path switching means for switching the connection relationship between the transmission device and the dual ring transmission line. , A master station that controls the configuration of the transmission line is provided with a configuration control unit that controls the determination of the fault position and the route switching unit, and an information transmission unit that transmits information between the configuration control units of other transmission devices. When the occurrence is detected, the configuration control means of each transmission device is instructed to transmit the supervisory signal via the information transmission means, and each transmission device transmits the supervisory signal to which its own address is added, and at the same time It was transferred information in the address of the monitoring signals to more receive the monitoring signal of its own delivery method for detecting failure point in a ring network and recognizes the addresses of stations at a time. 2. A method of recognizing addresses of a plurality of stations at a time according to claim 1, wherein a master station receives a supervisory signal from an upstream side to send a path command to each transmission device. Therefore, each transmission device transfers the address in the supervisory signal received from the upstream to the self-transmitted supervisory signal, and the master station recognizes the address information of a plurality of stations and compares it with the address connection information. A method of detecting a fault location in a ring network, which is characterized by recognizing the fault of the.