JP3152957B2 - Link switching control method for broadcast LAN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

(Contents) Industrial application field Conventional technology Problems to be solved by the invention Means and actions for solving the problems Embodiments Effects of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a link switching control method of an AN.

[0003] With the development of the information-oriented society, communication networks have come to play a broad role as a nervous system of social and economic activities, and their reliability has become particularly important. The reliability of the communication network is also very important in the facility management of public communication.

For example, when a LAN having a broadcast topology such as a bus-type LAN or a star-type LAN is introduced into a management area to be managed by a local management center, it is particularly important to ensure continuous communication. In addition, it is necessary to reduce the running cost such as the initial cost when the LAN facility is introduced and the maintenance cost related to the facility operation.

[0005]

2. Description of the Related Art Conventionally, a management center in a certain area is provided with a bus type LAN or a star type LA as a management medium in a management area.
LA having a broadcast configuration topology such as N
When N is introduced, it is common to adopt a form in which a plurality of offices or stations are connected to one LAN link path and managed by a management center.

However, in such a configuration, LA
Since there is one N link path, any part of the LAN link path may be disconnected,
If the connection between the LAN link path of the receiver and the station and the station is damaged, communication cannot be performed until such a failure is repaired, and continuous communication is performed and the management center performs centralized management. Will be reduced.

Therefore, as shown in FIG. 9, a working LAN link path 2 and a plurality of backup LAN link paths 3a,.
, 4n are connected to a multiplexed LAN link path 1 composed of 3n, and a link switching control method of a broadcast LAN is considered.

[0008] As shown in FIG.
A plurality of LAN media access control devices (hereinafter referred to as MACs) 5a, 5 of the respective node stations 4a, 4b,.
b,..., 5n, and these MACs 5a, 5b,.
5n is connected to a CPU module 7 for controlling LAN logical connection via a CPU bus line 6.

According to this method, for example, the working LAN link path 2 is disconnected or the working LAN link path 2 is disconnected.
When the MAC 5a connected to the LAN fails, the control of the CPU module 7 controls the other standby LAN link path 3
The communication can be performed by switching to the MACs 5b,..., 5n connected to a,.

According to such a system, a continuous service without interruption of communication can be provided.
This method is similarly effective in general-purpose LAN facilities in a service field where reliability is required.

[0011]

By the way, in the above-described link switching control method of the broadcast LAN, the multiplexed LAN link paths 2, 3a,.
, 5n corresponding to the number n, the initial cost for introducing the facility increases, and the running cost for maintenance, etc., corresponding to the increase in the number of parts. Is high.

Accordingly, an object of the present invention is to provide a broadcast configuration L capable of providing a continuous service without interruption of communication and lowering the initial cost at the time of introducing a facility and the running cost such as facility maintenance.
An object of the present invention is to provide an AN link switching control method.

[0013]

According to one aspect of the present invention, a broadcast configuration L in which a plurality of node stations are connected by a working LAN link path for normal communication and at least one backup LAN link path.
An AN link switching control method, wherein each node station comprises: a transmitting means for transmitting a communication signal; a receiving means for receiving a communication signal; a pilot signal inserting means for inserting a pilot signal into the communication signal; Means for detecting a pilot signal inserted into the signal; and link path switching means for switching the working LAN link path to one of the backup LAN link paths when the pilot signal is no longer detected; A pilot signal is inserted into the communication signal propagating through the working LAN link path by the pilot signal inserting means of the node station having the right as a master supervisor among the node stations, and the inserted pilot signal is used as the master supervisor. Of other node stations that do not have The communication is performed while maintaining the working LAN link path by detecting with the pilot signal detecting means; in response to the pilot signal being no longer detected by at least one of the other node stations, the communication with the master supervisor node station is performed. The link path that the link path switching means performs communication is changed from the working LAN link path to one of the backup LAN link paths.
And a link of a broadcast-structured LAN for switching a link path with which the link path switching means of the other node station performs communication from the working LAN link path to the backup LAN link path from which a pilot signal is detected. A switching control scheme is provided.

The node station having the right as the master supervisor is fixedly set in advance or selected by means such as a token acquisition method. Each node station includes notification means for periodically notifying the master supervisor node station of the detection of the pilot signal.

Preferably, each node station generates an idle signal by generating an idle signal, and transmits the idle signal to a spare L on which no pilot signal is propagated.
Means for sending to the AN link path and means for detecting an idle signal are included.

According to another aspect of the present invention, there is provided a link switching control method for a broadcast-structured LAN in which a plurality of node stations are connected by an active LAN link path for normal communication and at least one standby LAN link path. A pilot signal insertion means for inserting a pilot signal into a communication signal; and a pilot signal insertion means for detecting when the pilot signal from the working LAN link path is no longer detected.
A master supervisor node station including first link path switching means for switching a link path to one of the backup LAN link paths; means for detecting a pilot signal inserted in the communication signal; and periodic detection of the pilot signal. Notifying means for notifying the master supervisory node station in advance, and the pilot signal
A plurality of normal node stations including second link path switching means for switching the working LAN link path to a backup LAN link path in which the pilot signal is detected when the normal LAN station is detected from one of the AN link paths; A pilot signal is inserted into a communication signal propagating through the working LAN link path by the pilot signal inserting means of the master supervisory node station, and the inserted pilot signal is used as a pilot signal detecting means of the normal node station. Performs communication while maintaining the working LAN link path by detecting the pilot signal in at least one of the normal node stations. A link path for communication by the link switching means is switched from the working LAN link path to one of the backup LAN link paths, and a link path for communication by the second link path switching means of the normal node station is changed to the working LAN link path. A link switching control method for a broadcast-structured LAN for switching to a backup LAN link path in which a pilot signal is detected from a path is provided.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the description of each embodiment, the same components as those of the conventional example shown in FIG.

FIG. 1 shows a broadcast LAN according to a first embodiment of the present invention. The multiplexed link path 1 includes a working LAN link path 2 that is normally used and a backup LAN link path 3 that is used as a backup.
It is composed of A plurality of node stations 10 having the same configuration are connected to the multiplexed LAN link path 1. That is, each node station 10 has a pair of LANs.
Each LAN link path 2 by link path branch 8
3 is connected.

Each node station 10 switches between the working LAN link path 2 and the backup LAN link path 3 via the LAN link path branch 8.
And a LAN channel 12 for performing switching control and the like of the switch 11
And In this specification, such a configuration is referred to as 1 + 1
Defined as LAN link path spare configuration.

Referring to FIG. 2, there is schematically shown a broadcast LAN according to a second embodiment of the present invention. In this embodiment, the multiplexed LAN link path 1 is composed of one working LAN link path 2 and a plurality of backup LAN link paths 3,..., 3n. Multiple L
An AN link path branch 8 connects to each LAN link path.

The node station 10A has a working LAN link path 2 and a plurality of backup LAN link paths 3,.
n, and a LAN channel 12a for controlling switching of the switch 11a. Such a configuration is defined as a 1 + n LAN link path spare configuration.

Referring now to FIG. 3, there is schematically shown a broadcast LAN according to a third embodiment of the present invention. In this embodiment, the multiplexed LAN link path 1 is composed of a plurality of active LAN link paths 2,..., 2m and one backup LAN link path 3, and a plurality of node stations 10B having the same configuration are respectively provided. A plurality of LAN link paths 8 are connected to each LAN link path.

The node station 10B includes a switch 11b and a switch 11 for switching between a plurality of working LAN link paths 2,..., 2m and one backup LAN link path 3.
b, a plurality of LAN channels 12b ₁ ,
.., 12b _m .

In the third embodiment, a plurality of node stations 1 are connected to a plurality of active LAN link paths 2,..., 2m.
0B is connected, and any one of the working LAN link paths is rescued when it becomes unavailable.
This shows a configuration in the case where the backup LAN link path 3 is provided, and such a configuration is defined as an m + 1 LAN link path backup configuration.

Referring to FIG. 4, a broadcast LAN according to a fourth embodiment of the present invention is schematically illustrated. In the fourth embodiment, the multiplexed LAN link path 1 is composed of a plurality of active LAN link paths 2,..., 2m and a plurality of backup LAN link paths 3,.

A plurality of node stations 10C are connected to the multiplexed LAN link path 1 via a plurality of LAN link path branches 8, respectively. Each node station 10C is connected to a plurality of active LAN link paths 2,
, 2m and a plurality of backup LAN link paths 3, ..., 3n
, And a plurality of LAN channels 12c ₁ ,..., 1 for performing switching control and the like of the switching unit 11c.
2 _cm .

Such a configuration is defined as an m + n LAN link path spare configuration. In this embodiment, the working LAN link paths 2,..., 2m can use any of the n backup LAN link paths 3,.

The configuration of the first to fourth embodiments of the present invention described above is based solely on the difference in the number of services in the working LAN link path at the normal time. Therefore, the 1 + n LAN of the second embodiment shown in FIG. It is believed that the operation of all embodiments of the present invention can be understood by describing the link path reserve configuration.

Next, with reference to FIG. 5, a schematic configuration and operation of the node station 10A will be described. The working LAN link path 2 and the plurality of backup LAN link paths 3,..., 3n are connected to the corresponding transceivers 20 via the LAN link path branches 8, respectively. The operation of the node station 10A differs depending on whether it is a master supervisor node station that has acquired the control right to control all other node stations or a normal node station that does not have the control right. The case will be described below.

First, the operation when the node station 10A functions as a normal node station will be described.

The transceiver 2 connected as described above
Numeral 0 performs half-duplex / full-duplex conversion or inverse conversion, and separates or combines the transmission signal output from the node station 10A and the reception signal input to the node station 10A. The received signal S transmitted from the working LAN link path 2 and received via the transceiver 20
1 is input to the valid reception signal selector 21 and also to the detectors 23 and 23 ′ connected to each branch 22 via the plurality of reception signal branches 22.

The detector 23 detects the effective link path indicating signal inserted into the received signal S1, that is, the pilot signal. The detector 23 'is a backup LAN link path 3, which is not used as a link path for communication at present.
.., 3n are detected.

When the detector 23 detects a pilot signal, a plurality of logic output signals S2 indicating the presence or absence of the pilot signal are input from the detector 23 to the valid reception signal selection discrimination circuit 24. It is output as a selection output signal S3. On the other hand, when the idle signal is detected by the detector 23 ', the idle signal is inputted to another discriminating circuit 24', and it is checked whether or not the link path through which the idle signal is transmitted is disconnected.

The valid reception signal selection output signal S3 is inputted to the valid reception signal selector 21 via the first bus line 25, whereby the valid reception signal S4 is inputted from the selector 21 to the receiving section of the LAN controller 26. You.
On the other hand, the output of the discriminating circuit 24 'is transmitted to the CPU system 28 via the first bus line 25 and the register 34, and the spare LAN link paths 3,.
Is recognized by the CPU system 28.

The LAN controller 26 is connected to a CPU system 28 by a CPU bus line 27.
It is controlled by a LAN manager included in the CPU system 28. That is, the LAN is handled based on the reception signal S4 input to the LAN controller 26.

If the information data extracted from the received signal S4 under the control of the CPU system 28 is intended for itself, it is determined that the information data is valid information addressed to itself from another node station 10A. 28, the I / O bus line 2
9 is stored in the external storage device 30 connected thereto.

When this information data is to be sent to another node station 10A, the target information data is extracted from the external storage device 30 and input to the CPU system 28 via the I / O bus line 29. . Then, the data is transferred to the transmission unit of the LAN controller 26 by the LAN manager of the CPU system 28 and converted into a transmission signal (serial signal) S5. The transmission signal S5 is input to the effective transmission path selector 32 as the transmission signal source S6 via the pilot signal / transmission signal switch 31.

In order for the effective transmission path selector 32 to transmit the transmission signal source S6 to any one of the link paths 2, 3,..., 3n, which transmission path is to be selected from the plurality of transmission paths 33 is as follows. Is determined as follows. First, information on the same path as the reception path indicated by the valid reception signal selection output signal S3 is stored in the valid signal selection register 34 and
The CPU system 28 recognizes it via the PU bus line 27. Then, under the control of the CPU system 28 based on the recognized information, the transmission path selection display is set in the register 34 via the CPU bus line 27.

The information set as the transmission path selection display is transmitted as the transmission control output signal S7 on the second bus line 3.
5 to the effective transmission path selector 32, and further from the effective transmission path selector 32 to the transmission signal source S6.
Is output to the transmission path 33 connected to the same transceiver 20 as the valid reception path.

At the same time, the transmission driver closing signal S for setting the transceiver 20 to high impedance is set.
9 is obtained by inputting the transmission driver control output signal S8 output from the LAN controller 26 to the effective transmission path selector 32 via the switch 31 and the transmission driver control line 37.

By the operation as described above, a valid signal transmitted from any one of the LAN link paths 2, 3,..., 3n is received, and the transceiver connected to the valid LAN link path. LA valid from 20
Transmission data is output to the N link path.

However, when the node station 10A functions as a normal node, the pilot signal / transmission signal switch 31 outputs the switching control output signal S1 output from the register 34 based on the recognition of the CPU system 28.
By 0, the transmission driver control output signal S8 and the transmission signal S5 are fixedly selected and output.

Next, the operation when the node station 10A functions as a master supervisor node station will be described.

In the node station 10A having the right of the master supervisor, a valid LAN link path indication signal, that is, a pilot signal must be transmitted to another normal node station 10A completely independently of the operation of the normal node station described above. No.

That is, the pilot signal / transmission signal switch 3
By periodically switching 1 to pilot signal transmission, the pilot signal S11 generated from the pilot signal generator 36 must be inserted into the transmission signal S5 and transmitted. This is performed by periodically setting the pilot signal / transmission signal transmission switching display in the register 34 via the CPU bus line 27 under the control of the CPU system 28 that recognizes that the device is the master supervisor. Is done.

The information set in the register 34 is sent to the switch 31 via the second bus line 35, and the mode of the switch 31 is switched to pilot signal transmission. Then, the pilot signal S11 is input to the effective transmission path selector 32 via the switch 31 as the transmission signal source S6.

Here, the function as a master supervisor is connected to a valid link path whose use is currently designated, so that pilot signal S11 is transmitted to another node station 10 which is a normal node.
A is transmitted to A. Normal node station 1
The pilot signal S11 received at 0A causes an operation similar to the operation of the received signal at the normal node described above, and is connected to a valid LAN link path specified by the master supervisor node station.

A plurality of idle signal generators 38 are connected to the selector 32.
Respectively generate a different idle pattern signal having a priority for standby switching. The idle signal is all L except for the LAN link path through which the pilot signal is transmitted.
The LAN link path which is sent out to the AN link path and is to be used next is determined by the priority of the pattern.

When the detector 23 of the normal node station 10A cannot detect the pilot signal, the determination circuit 24 determines that a failure has occurred in the LAN link path connected to the detector. For example, when it is determined that a failure has occurred in the working LAN link path 2, this failure information is recognized by the CPU system.

The master supervisor node station monitors whether or not communication with the normal node station is always performed normally, and performs communication via the effective LAN link path designated by itself. Normal and abnormal communication
It is recognized by the presence or absence of a response from the normal node station to the arrival confirmation request from the master supervisor node station.

Therefore, the normal node station 10
If there is no response to the arrival confirmation request within a predetermined period from A, the master supervisor node station 10A recognizes that a failure has occurred in the LAN link path used so far.

The selector 32 of the master supervisor node station 10A switches the communication path to the LAN link path through which the highest priority idle signal flows. On the normal node station side, the detector 23 detects a pilot signal to detect
It is possible to easily determine whether the link has been switched to the N link paths 3,.
Communication is performed via a link path.

By detecting the idle signal, it is possible to check whether or not the LAN link path through which the idle signal is flowing is disconnected. Further, by assigning a priority to the idle signal, the standby LA to be switched next is switched.
N link paths can be specified.

The valid LAN link path currently designated for use is specified as a default link path at the time of initial startup, and thereafter changed as long as communication between the master supervisor node station and the normal node station is normally performed. Or it is changed to another LAN link path for any reason that causes a normal communication interruption, and then the link between the master supervisor node station and the normal node station is up to now. Either communication is continuing normally.

There are two methods for determining the master supervisor node station: a fixed setting method and a variable setting method.
The fixed setting method is effective when there is only one device that can be a master supervisor node station in a system in which communication is performed. The fixed setting method is a method in which the master supervisor node station and the normal node station are fixed, and are not changed after the setting.

The change setting method is based on the token acquisition method of the token bus specified in IEEE802.4.

The reception operation at the master supervisory node station is performed by a setting reception control output signal having the same control information as the transmission control output signal S7 output from the register 34 designating the transmission side LAN link path of the own node. By giving S12 to the valid reception path selector 21, the selection is controlled and performed.

However, the setting reception control output signal S12 includes:
If the master supervisor node station / normal node station valid selection information is included and this information flag indicates that the master supervisor node station is valid, the valid reception signal selection output signal S3 output from the determination circuit 24 is valid reception. Path selector 21
Invalidated.

Next, the detailed configuration and operation of the node station shown schematically in FIG. 5 will be described with reference to FIGS. 6 and 7.

In FIG. 6, reference numeral 50 denotes a receiver, and reference numeral 51 denotes a driver. Both the receiver 50 and the driver 51 terminate the working LAN link path 2. 50 '
Is a receiver terminating the backup LAN link path 3, 51 '
Is a driver. The received signal S20 or S20 'received by the receiver 50 or 50' is input to the service state controller 52 or 52 'and also to the valid received signal selector 53.

Service state controllers 52, 52 '
Is a valid L from the input reception signals S20 and S20 '.
By detecting a pilot signal indicating that it is an AN link path, a signal indicating whether the received signals S20 and S20 'are valid is output.

The signals output from the output terminals 52b and 52b 'of the service state controllers 52 and 52'
The valid reception signal selector 53 is controlled, and the valid reception signal S21 is input to the reception end 54b of the LAN controller 54.

The service state controllers 52, 5
The signals output from the output terminals 52a, 52a 'of 2' are signals indicating the presence or absence of a pilot signal, and are input to the CPU system 56 via the I / O register 55 and the CPU bus line 57. The presence or absence of a pilot signal is recognized.

Further, the CPU system 56 includes a LAN controller 54 connected by a CPU bus line 57.
And a LAN manager that controls the LAN and controls the LAN. The CPU system 56 transmits information to an external CPU system that needs communication with the LAN controller under the control of the LAN manager of the CPU system 56. The signal is output from the transmitting end 54a of the terminal 54.

The transmitting end 54 of the LAN controller 54
The transmission signal S22 output from the controller 51 is transmitted to the drivers 51, 5 via the control loopback selectors 58, 58 '.
1 '. Whether the input valid transmission signal S22 is output from the drivers 51 and 51 'is determined by the RTS (Requeue) output from the output terminal 54c of the LAN controller 54 indicating the validity of the transmission signal S22.
(St To Send) signal S23 is controlled and determined by signals S24 and S24 ', which are output from the output terminals 52a and 52a' of the service state controllers 52 and 52 'and indicate the presence or absence of a pilot signal.

That is, the control of the driver 51 or 51 ′ having the pilot signal and terminating the LAN link path 2 or 3 which is determined to be valid is controlled by the RTS signal S 2
3, the configuration is such that the valid transmission signal S22 is output to the valid LAN link path 2 or 3.

Reference numerals 59 and 59 'denote loop-back mechanisms for performing line loop-back, and are used for specifying a faulty line and a faulty node of a LAN link path. In this line loopback, the CPU system 56
There is a control loopback performed based on the above control and a forced loopback performed manually regardless of the control loopback.

The control loopback is executed by the CPU system 56.
Is performed through the I / O register 55, and the forced loopback is performed directly by the switch 60. This result is verified by the loopback verification mechanism and used for maintenance purposes.

In the verification by the loopback verification mechanism, when the loopback is performed by the loopback mechanisms 59 and 59 ′, the execution result signal is transmitted via the receivers 50 and 50 ′, and the exclusive signal constituting the loopback verification mechanism is obtained. OR elements 61, 61 'and a data flip-flop (DF
F) are transmitted to 62 and 62 ', and
5 is input to the CPU system 56 via the CPU 5.

Next, the operation of the service state controllers 52 and 52 'shown in FIG. 6 will be described with reference to FIG.

Here, the valid reception signals S20,
S20 'and the transmission signal S22, that is, the LAN node 10A
The configuration of a communication signal for communicating between them will be described. This communication signal is configured by inserting a pilot signal Sp between main information signals Sa, as shown in FIG. Further, as the pilot signal Sp, an alternating signal having a relatively long cycle which does not appear in the main information signal Sa (hereinafter, referred to as a long cycle alternating signal) is used.

In FIG. 7, reference numerals 65 and 65 'denote counting counters of the components of the service state controllers 52 and 52'. The counting counters 65 and 65 'receive the received signal S
20 and S20 ', the alternating edges of the long-period alternating signal (pilot signal Sp) are counted within a fixed interval.
This is to calculate the maximum number included, and the counting counters 65 and 65 'according to the calculated value, that is, the count number.
Is changed from, for example, "1" to "0" and from "0" to "1".

For example, if the counted number of the alternating edges exceeds the maximum value, the next constant interval trigger is input to the counters 65 and 65 ', and the counting is stopped until the counters 65 and 65' are reset. Becomes

Further, only when the next constant interval trigger is input before the count exceeds the minimum value and before the count exceeds the maximum value, it is recognized that the pilot signal has been detected, and this state is counted. The particular counting logic output signal representing the output state of 65, 65 'is represented by a "1" or "0".

This operation is always performed at regular intervals, and one pilot signal detection continues for the regular interval. Therefore, this state is continuously maintained while the pilot signal is being detected. This operation is supported by pilot signal detectors 66, 66 '.

When the main information signal between the node stations, not the pilot signal, is transmitted to the LAN link path 2 or 3 (see FIG. 7), the pilot signal is inevitably lost. There is no signal.

However, even if the pilot signal detection signal disappears, whether the valid LAN link path has designated the working LAN link path 2 in the interval before the pilot signal detection signal disappears, or Since the service status indicators 67 and 67 'hold whether or not the LAN link path 3 has been instructed, the valid LAN link path designation is changed and the active LA link path is changed.
There is no switching from the N link path 2 to the backup LAN link path 3, or from the backup LAN link path 3 to the working LAN link path 2.

However, if a pilot signal is detected in the backup LAN link path 3 at an interval after the interval in which the pilot signal has been detected in the working LAN link path 2, for example, the effective LAN link path up to that point is changed. From the working LAN link path 2 to the standby LA
Switch to N-link path 3.

In the interval after the interval, the main information signal is transmitted between the LAN nodes.
When the pilot signal does not appear, the designated state of the valid LAN link path designated at the time interval is maintained until the pilot signal appears.

Reference numeral 68 denotes a reference timing generator. This generator 68 has an oscillation frequency of 3
A 2/5 MHz signal is divided by 512 or 256 to generate a pilot signal S25 (which indicates the pilot signal Sp in FIG. 8), and a 4 frequency divided signal S26 and 8 which becomes a reference timing in the node station 10. A frequency-divided signal S27, a frequency-divided signal applied to the management area indicated by a broken line, and a frequency-divided signal applied to an office or the like in the management area are generated.

When the node station 10A is recognized as a master supervisor node station, a signal indicating the presence or absence of a pilot signal is output from the output terminal 52a of the service state controller 52 or the output terminal 52a 'of the service state controller 52' on a periodic basis. And the pilot signal S25 output from the reference timing generator 68 is output from the driver 51 or 51 'via the selector 58 or 58' shown in FIG. At the same time, the RS for enabling the driver 51 or 51 '
The T signal S23 is controlled by the signal indicating the presence or absence of the pilot signal.

In each of the embodiments described above, a plurality of node stations having the same configuration are connected to the multiplexed LAN link path, and one node station is selected as a master supervisory node station to perform communication between the node stations. Will be The link path maintained by inserting a pilot signal into the communication signal at the master supervisory node station and detecting this pilot signal at other node stations is used by all node stations.

If it becomes difficult to maintain the working LAN link path for some reason, the pilot signal is transferred to another protection LAN link path, thereby making the working LA link available.
Communication can be performed by switching the N link path to the backup LAN link path.

In each of the embodiments described above, the configurations of the node stations are all the same. However, the present invention is not limited to this, and the master supervisor node station is designed separately and the other It is also possible to use a node station that does not have the function of the master supervisor node station as a station.

In this case, the master supervisor node station is fixedly set and cannot be changed, but the function as the master supervisor node station can be omitted from the normal node station. Costs can be greatly reduced.

[0086]

As described above, according to the present invention,
Since the multiplexed LAN link path can be easily switched, it is possible to provide an uninterrupted communication service and to reduce the initial cost and the running cost such as facility maintenance when introducing the facility. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram for explaining a link switching control method of a broadcast-structured LAN constituted by 1 + 1 LAN link paths according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram for explaining a link switching control method of a broadcast-structured LAN constituted by 1 + n LAN link paths according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram for explaining a link switching control method of a broadcast-structured LAN constituted by m + 1 LAN link paths according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram for explaining a link switching control method of a broadcast-structured LAN composed of m + n LAN link paths according to a fourth embodiment of the present invention.

FIG. 5 is a schematic circuit diagram of a node station of the broadcast LAN shown in FIG. 2;

6 is a circuit diagram showing the configuration of the node station shown in FIG. 5 in more detail.

FIG. 7 is a circuit diagram of the service state controller shown in FIG. 6;

FIG. 8 is a schematic configuration diagram of a communication signal transmitted between node stations in each of the embodiments described above.

FIG. 9 is a schematic configuration diagram for explaining a conventional link switching control method of a broadcast configuration LAN.

[Explanation of symbols]

 1 LAN link path 2, ..., 2m Working LAN link path 3, ..., 3n Backup LAN link path 10,10A, 10B, 10C Node station

Continuation of the front page (56) References JP-A-4-207338 (JP, A) JP-A-4-145742 (JP, A) JP-A-4-58636 (JP, A) JP-A-3-261244 (JP) JP-A-3-40618 (JP, A) JP-A-3-23736 (JP, A) JP-A-2-272842 (JP, A) JP-A-1-258522 (JP, A) JP 62-167439 (JP, A) JP-A-57-16697 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/28-12/40

Claims (5)

(57) [Claims] 1. A broadcast configuration L in which a plurality of node stations are connected by an active LAN link path for normal communication and at least one backup LAN link path.
An AN link switching control method, wherein each node link station includes: a transmitting unit for transmitting a communication signal; a receiving unit for receiving a communication signal; a pilot signal inserting unit for inserting a pilot signal into the communication signal; Pi for detecting pilot signal inserted in communication signal
Lot signal detection means; and when the pilot signal is no longer detected, the working L
Link path switching unit switches to one of the AN link path the preliminary LAN link path; and an idle signal generating means for generating an idle signal; pre pilot signal the idle signal is not propagated
Idle signal transmitting means for transmitting to LAN link path
If; includes an idle signal detecting means for detecting an idle signal; by the pilot signal insertion means of the node station has the right as an internal master supervisor of the plurality of nodes stations, the communication signal propagating through the active LAN link path And the pilot signal is detected by the pilot signal detecting means of another node station which does not have the right as a master supervisor.
The communication is performed while maintaining the link path. In response to the fact that at least one of the other node stations cannot detect the pilot signal, the link path switching means of the master supervisory node station performs the communication. In addition to switching from the working LAN link path to one of the backup LAN link paths, a link signal with which the link path switching means of the another node station communicates is detected from the working LAN link path by a pilot signal. A link switching control method for a broadcast-structured LAN for switching to the backup LAN link path. 2. Normal communication between a plurality of node stations.
Working LAN link path performed and at least one spare
Broadcast configuration L connected with LAN link path
An AN link switching control method, in which each node link
Station: transmitting means for transmitting a communication signal ; receiving means for receiving a communication signal ; and pilot signal insertion for inserting a pilot signal into the communication signal.
Input means; a pie detecting a pilot signal inserted into the communication signal
Lot signal detecting means; when said pilot signal is no longer detected, said working L
Switch the AN link path to one of the backup LAN link paths
Switching path switching means; a master supervisor of the plurality of node stations.
Said path of the node station that has the right
Said working LAN link by means of an inserted signal signal
A pilot signal is inserted into the communication signal propagating through the path,
The pilot signal with
Pyro of other node stations that do not have the right to
The working LA is detected by the
Communicate while maintaining N-link path; Pyro at at least one of said other node stations
The master signal in response to the
Disconnect the link path of the supervisor node station
The link path through which the switching means communicates with the LAN link path
Switch to one of the backup LAN link paths from
The link path switching means of the other node station
The working LAN link path through which the stage communicates
The spare signal from which a pilot signal is detected from
Switch to LAN link path; replace multiple node stations with multiple active LAN link paths
And a switchover control method of a broadcast-structured LAN connected by a single standby LAN link path . 3. Normal communication between a plurality of node stations is performed.
Working LAN link path performed and at least one spare
Broadcast configuration L connected with LAN link path
An AN link switching control method, in which each node link
Station: transmitting means for transmitting a communication signal ; receiving means for receiving a communication signal ; and pilot signal insertion for inserting a pilot signal into the communication signal.
Input means; a pie detecting a pilot signal inserted into the communication signal
Lot signal detecting means; when said pilot signal is no longer detected, said working L
Switch the AN link path to one of the backup LAN link paths
Switching path switching means; a master supervisor of the plurality of node stations.
Said path of the node station that has the right
Said working LAN link by means of an inserted signal signal
A pilot signal is inserted into the communication signal propagating through the path,
The pilot signal with
Pyro of other node stations that do not have the right to
The working LA is detected by the
Communicate while maintaining N-link path; Pyro at at least one of said other node stations
The master signal in response to the
Disconnect the link path of the supervisor node station
The link path through which the switching means communicates with the LAN link path
Switch to one of the backup LAN link paths from
The link path switching means of the other node station
The working LAN link path through which the stage communicates
The spare signal from which a pilot signal is detected from
Switch to LAN link path; replace multiple node stations with multiple active LAN link paths
And a link switching control method for a broadcast-structured LAN connected by a plurality of backup LAN link paths . 4. Normal communication between a plurality of node stations
Working LAN link path performed and at least one spare
Broadcast configuration L connected with LAN link path
An AN link switching control method, wherein a pilot signal is inserted into a communication signal.
Input means and a pilot from the working LAN link path.
When the signal is no longer detected, the working LAN link
Switch to one of the backup LAN link paths
Link path switching means and an idle signal generating idle
Signal generation means, and a pilot signal
Eye to send to the backup LAN link path that has not been propagated
Master Supervisor No. Including Dollar Signal Sending Means
A station for detecting a pilot signal inserted into the communication signal ;
Periodic detection of pilot signal and pilot signal detection
To the master supervisor node station
Notification means, and a pilot signal transmitted from the standby LAN link.
When it is detected from one of the paths, the working L
An AN link path is reserved for the pilot signal being detected.
Second link path switching means for switching to a LAN link path
And idle signal detecting means for detecting an idle signal.
And a plurality of normal node stations including the master supervisory node station.
Said working LAN link by means of an inserted signal signal
A pilot signal is inserted into the communication signal propagating through the path,
The pilot signal with the normal node station
Detection by the pilot signal detection means
Communicate while maintaining the working LAN link path; at least one of the normal node stations performs communication.
When the Ilot signal can no longer be detected,
The first link of the supervisor node station
The link path with which the path switching means communicates is set to the working LA.
Switch from N link path to one of the backup LAN link paths
As well as the normal node station
The link path with which the second link path switching means performs communication is
A pilot signal is detected from the working LAN link path
A link switching control method for a broadcast-structured LAN for switching to the backup LAN link path . 5. An apparatus according to claim 1, wherein said idle signal generating means is in a switching priority order.
Idle signals with different patterns
A plurality of idle signal generators for generating
The idle signal transmitting means is connected to each backup LAN link path.
Adapted to transmit different idle signals.
If a failure occurs in the working LAN link path,
The working LAN link path according to the priority of the idle signal.
請switch from scan to one of the pre-LAN link path <br/> Motomeko 1 or 4 broadcast configuration LAN link switching control method described.