JPH03123235A - Fault demarcation method in ring network and ring line constitution method with demarcation - Google Patents

Abstract

PURPOSE:To demarcate an assumed fault location roughly depending on whether a specific frame S2 is received by a station A1 or not and to restore the network function quickly by allowing the station A1 just subsequent to the fault location to send the specific frame S2 to a specific ring line. CONSTITUTION:Stations A1-A4 send a fault notice frame S1 in the occurrence of a fault of a normal line B at an interval of a prescribed time and a station receiving the frame S1 from other station stops the transmission immediately at the same time. When the station A1 is discriminated to be a station just subsequent to a fault location in the occurrent of the fault, the sender side for the normal line B of its own station is looped back to a standby line C and the reception side for the line B is looped back to the standby line C to constitute the specific ring line R comprising the station A1 and the line C and the station A1 sends a specific frame S2 to the circuit R. An assumed fault location is demarcated roughly depending whether the frame S2 is received by the station A1 or not and the fault location roughly demarcated is disconnected individually to form ring circuits shown in Figures (c), (d) thereby restoring the network function.

Description

Detailed Description of the Invention (Industrial illumination field) The present invention relates to a ring network in which a plurality of stations are connected in a ring by normal lines and protection lines having transmission directions in opposite directions. The present invention relates to a method for configuring a new link line that maintains network functions by isolating the faulty location when a fault occurs.

(Prior Art) A ring network, which is one type of communication control line, is constructed by connecting a plurality of stations in a ring through normal lines and protection lines having mutually opposite transmission directions. In this network, during normal times, communication is carried out between convex circuits using a normal line (a network is configured), and when an abnormality occurs, signals are looped back from the normal line to the protection line, or from the protection line to the normal line, and the signal is returned to the fault point. A new ring circuit is configured from which the network is disconnected, and network functionality is maintained on this new ring circuit.

Conventionally, the most common method of configuring a new ring line is to set up a specific management station within the network that performs loopback control, and when that management station recognizes the occurrence of a fault, the A loopback request frame was sent to a station that needed to loop back a signal, and the station that received the frame looped back the line to disconnect the faulty part and form a new link line.

However, this ring line configuration method has the problem that if the management station itself fails, return control cannot be performed and a new ring line cannot be configured, so that the network function cannot be restored.

Therefore, new ring line configuration methods have been developed in which loopback control is distributed to each station, and one of the main methods is described in Japanese Patent Laid-Open No. 61-239744.

In this ring line configuration method, first, in a ring network as shown in FIG.
Only station A, which does not receive the fault notification frame S, continues to send the fault notification frame S1, and each station other than station A receives the fault notification frame S by receiving the fault notification frame S. The transmission of the frame S1 is stopped, and the shallow area A directly below the fault location is determined.

The predicted failure locations at this time are @, ■, ■, @ in Figure 6.
There are four points. That is, (2) A failure point in the communication path B between the stations A2 and A, which are directly upstream of the station A1.

(2) A failure point in the sending ring interface E2 of the normal line, the communication control mechanism F, or the return switch G2 of the normal line in the interval A2 shown in FIG.

■, Point of failure such as power outage of the station A□.

(2) A failure point in the receiving side ring interface E1 of the normal line, the communication control mechanism F, or the return switch G1 of the protection line in the interval A shown in FIG.

can be assumed.

Therefore, in this ring line configuration method, each station A1 to A
The layer A2 immediately above the station A1 is detected from the configuration information P of the connection order between the own station and other stations stored in
As shown in FIG. , by disconnecting the failure point (2) in the communication path B between stations A2 and A1 shown in FIG. 6, and creating a new ring line (as shown in FIG. 5).
Stations A+ A-A, -At A3-A, -A,) are configured.

If the network function is not restored by this new ring line, station A sends a return request frame F to station A3, which is immediately upstream of A2, and returns to station A as shown in FIG. 5C. , the normal line B is looped back to the protection line C to completely disconnect station A2, and the failure point @ of the transmitting section of station A2 shown in FIG. A new ring line (as shown in Figure 5C)
Station A, -A, -A, -A, -A,
) to restore the network function (problem to be solved by the invention) However, the ring line configuration method shown in FIG. 5 described above has the following problems.

■ If there is a failure point ■ on the receiving side of the normal line of station A as shown in FIG. , or the return switch G of the normal line.
If a failure occurs in a portion that cannot be avoided by turning back as shown in Fig. 4, c, the network function will not be restored in the ring line shown in Fig. 4, c.

① In order to solve the above problem ②, if the network function does not recover even after a certain period of time has passed after the station A returns, that is, after configuring the ring line shown in Figure 5, c. It is conceivable that the backup line C of the station A4, which is a station directly downstream of the station A1, is looped back to the normal line B to form a new ring line. However, since there are many (switches) required to reach this point, the burden on the software and hardware for sending or receiving the signals is large.
Implementation will be costly. Furthermore, each time a ring line is configured, it is necessary to wait for a predetermined period of time and confirm that the network function has been restored.
If the network function cannot be restored unless all ring lines of -d are configured, it will take time to restore the network function.
-It is unsuitable for today's ring networks, which are expected to return to function as soon as possible.

(Purpose of the Invention) The purpose of the present invention is to broadly classify the failure points that have occurred in the ring network, to configure ring lines from which only the broadly classified failure points are individually isolated, and to quickly restore the network function. An object of the present invention is to provide a method for configuring a ring line for a non-long network.

(Means for Solving the Problems) A method for classifying failure points in a ring network according to the first claim of the present invention is as follows:
In a conventional ring network in which station A1 is networked with The transmitting side for normal line B of 5 is looped back to protection line C, and the receiving side for normal line B is looped back to protection line C to form a specific ring line R consisting of only station A1 and protection line C. A specific frame S2 is sent to this ring line R, and the same frame S2 is sent to the same port! ! This feature is characterized in that the expected failure locations are broadly classified depending on whether the signal is received by the local station via R or not.

A method for configuring a ring line of a ring network according to claim 2 of the present invention is a method for configuring a ring line in a ring network according to claim 1 as shown in FIGS. 1b and 2. When the specific frame S2 is received by the station A1 via the specific ring line R, the first
As shown in Figures c and d, a new ring line is constructed by separating the predicted failure points into pieces/7, and as shown in Figure 2, the specific frame 8□ is connected to the specific ring line R.
If the reception is not received at station A via This system is characterized by the fact that it is possible to construct a ring line in which parts are separated individually.

(Function) In the ring line configuration method according to the ring network failure classification method of the present invention, after the station A immediately downstream of the failure point is specified, the station A is connected to a specified ring consisting of only its own station and the protection line C. Since line R is configured and a specific frame S2 is sent to the same line R, the expected failure locations are roughly divided depending on whether or not the same frame S2 is received by the local station (
If reception is received, only the faulty parts broadly classified by this are separated, and if no reception is received, only the faulty parts roughly classified by this are separated. The network function can be restored quickly by using a ring line.

(Example) FIGS. 1 to 4 show ring networks embodying the present invention.

Figures 1 and 2a on the other side of these figures are the same, A and ~A4 are four stations connected in a ring to form a network, and B is a normal network connecting each station A1 to A4. Line C is its backup line, and these four lines B and C have transmission directions in opposite directions to each other, as in the past, and normally only the normal line B constitutes a ring line (the network is not configured). ), when an abnormality occurs, it is possible to loop back the signal from normal line B to protection line C, or from protection line C to normal line B, isolate the fault, and configure a new ring line to continue maintaining network functions. It is possible to do so. Further, the number of the stations A, to A4 may be greater than or equal to the number described above.

As shown in FIG. 3, each of the stations A1 to A4 includes a communication control mechanism 11, ring interfaces 12a to 12d, and return switches 13a to 13d.

11? i ring interface 1.2a=d is the third
As clearly shown in the figure, they are provided on the receiving side and the transmitting side of the normal line B, and on the receiving side and the transmitting side of the i'-equipped line, respectively. This ring interface 12a-ci is provided with a clock pulse extraction circuit, a (V circuit, etc.).Also, when using optical fiber cables for the normal line B and the backup line!!lc, the ring interface +
Opto-electronic devices may be provided within 2a-d. (-1
"u L, these circuits and mechanisms are the communication control mechanism 1.
You can implement it in 1 (/X.

The return switches 13a-d are provided with normal line return switches 13a, 13c and protection line return switches 13b, +3d, as shown in FIG. Among these, the return switches 13a and 13c for the normal line are switched to the positions shown by the virtual lines in FIG. 1
The line is switched to the position indicated by the virtual line in FIG. 3 by the backup line return signal +4b output from 1.

FIG. 4 shows a failure communication frame Sl used in the present invention, which is defined in IEEE802.5. Among the fields in the figure, 21 is a start delimiter (StartDeliIIi) indicating the start of the frame.
Ler: SD), 22 is a frame control (FraLle ConLrol) indicating the type of frame.
: FC), 23 is the destination station address (Destination
ion Address: DA), 24 is the source address (SA), 25 is the exchange information (Infor IIation: INFO)
, 26 is a frame check sequence (FrameCh
eck 5 sequence: FC3), 27 is an end limiter (End Deli) indicating the end of the frame.
miter: ED), of which exchange information 25
Only the following fields are of variable length, and the other fields are of fixed length. Incidentally, when used as the failure notification frame S in the present invention, the field length of the exchange information 25 is 0, and the address 23 of the destination station is a broadcast address (BroadcastAddress).
address (addressed to all stations) is used. This communication frame may be of a type other than the above.

In the present invention, each of the stations A1 to A4 is given in advance configuration information P regarding the connection order between the own station and other stations. As in the past, this configuration information P is a criterion for determining the relative position of the failure location and the own station when each station A, to A4 on the network experiences an abnormality. For this configuration information P, a station presence frame (a frame that each station A sequentially sends at regular intervals) defined in IEEE 802.5 (an international standard specifying a token passing ring type access method) may be applied.

Now, in the ring line configuration method of the ring network of the present invention, 0 to A4 to each station are normally connected to the first line when an abnormality occurs on line B.
As shown in Figure a and Figure 2a, the failure notification frame S1 is sent out at regular intervals, and at the same time the failure notification frame S1 from other stations is transmitted.
The station that receives the message 1 immediately stops sending it and performs failure notification competition. (This competitive method has traditionally been used in IEEE80
2.5 is the media access control specified in Article 2.5.
According to the same regulations, the failure notification frame Sl is called a beacon frame. ) Therefore, only station A that does not receive the failure notification frame S1 continues to send out the frame Sl, and station A
, the other stations A2 to A4 determine the relative positions of the station A1 and their own station from the same frame Sl and the configuration information P. In this embodiment, each station A1 to An starts the contention end waiting timer at the same time as the sending of the failure notification frame S1 starts, and if the failure notification frame S1 is received while the timer is operating, the This timer stores the source station address 24. This timer has a time constant sufficient for the failure notification frame contention to end, and when the timer ends, each station A, -A receives the last received signal. The relative position is determined from the originating station address 24 of the fault notification frame S1 and the configuration information P.

The expected failure locations at this time are ■, ■, ■, and ■ in Figure 6.
There are four points. That is.

(2) A failure point in the communication path B between the stations A2 and A1 immediately upstream of the station A.

(2) A failure point in the sending-side ring interface +2a of one normal line in the station A2 shown in FIG. 3, the communication control mechanism 11, or the return switch 13a of the normal line.

(2) Point of failure such as power outage of the station A2.

■ Of the Nij station A shown in Fig. 3, the reception side ring interface 12b of the normal line
! Or the failure point of the return switch +3b of the protection line.

6 At that point, if station A determines that it is the station immediately upstream of the failure point when an abnormality occurs, it will use its normal line B as shown in Figures 1b and 2. The transmitting side of the normal line B is looped back to the protection line C, and the receiving side of the normal line B is looped back to the protection line C to form a specific ring line R consisting of only the station Al and the protection line C. In the ring line configuration method according to the present invention, which transmits a specific frame S2, the failure location classification is roughly classified into the expected failure locations (failure points) depending on whether or not this specific frame S2 is received by the station A1. ,
If the signal is received, a ring line as shown in Figure 1 c and d is constructed by disconnecting the faulty parts that are broadly classified at that time, and if it is not received, the ring line shown in Figure 2 C is constructed in which the faulty parts that are roughly classified at that time are disconnected. An example of configuring such a ring line and restoring the network function will be described in detail below. Incidentally, in this embodiment, the failure notification frame S1 is used as the specific frame S2.

If the same frame S2 is received by the own station via the same line R as shown in Figure 1, then among the predicted failure points, ■, ■, ■ as shown in Figure 1 will be detected. Fault locations are broadly classified. That is, they are the stations A immediately upstream of the station A1, ~
Fault point ■ of communication path B between A1, said station A shown in FIG.
One of them is the sending side ring interface 12 of the normal line.
a, communication control mechanism It, or normal line return switch 1
3a's failure point ■ is a failure point @ such as power cutoff of the station A (FIG. 6).

Therefore, in this embodiment, first, as shown in FIG.
1 returns the protection line C received by the own station to the normal port &IB, and at the same time sends a first return request frame S to the station A2, which is the station directly upstream of the station A1.

The station A2 returns the normal line B that it receives to the protection line B as shown in Figure 1C. At this time, the communication path B between station A2 and station A1, that is, the failure point in Figure 6 A new ring line (stations Al-A, -A
3-A! -A3-A4-A1) is configured. In this embodiment, the restoration of the network function is confirmed when the first return request frame S is received again at station A via each station A1 to A4 of this line, and after confirmation, the subsequent ring The line configuration was changed to 1st grade.

Next, if the network function is not restored using this ring line even after a certain period of time has passed, station A1 becomes a station immediately upstream of station A2 (a station two upstream of station A), as shown in Figure 1d. station A) sends a second return request frame S4 to station A, and station A sends a second return request frame S4 to station A, and station A uses the normal line B that it receives.
is returned to backup line C. At this time, five stations A2 are completely disconnected, and among the stations A2, the communication control III structure 1 shown in FIG.
1. Normal line transmission side ring interface 12a,
A new ring line (station A 1 - A
--A 3- A 4- A 1) is constructed.

As a result of the above, a ring line is configured in which all of the predicted failure points that are broadly classified by reception of the specific frame S2 are disconnected, and the network function is restored by one of the ring lines.

On the other hand, if the same frame S2 is not received at the local station via the same line R as shown in Figure 2, then the failure point (■) among the predicted failure points will be detected as shown in Figure 2. That is, the failure point @ of the reception side ring interface 12b of one normal line, the communication control mechanism 11, or the return switch 13b of the protection line in the interval A1 shown in FIG. 3 is identified. (FIG. 6) Therefore, in this embodiment, as shown in FIG. Normal line B is returned to backup line B.

At the same time, station A1 sends a fourth loopback request frame s6 to station A4, which is immediately downstream thereof, and station A4 loops back the backup port t6Ac that it receives to normal line B.
As a result, station A is completely disconnected as shown in Figure 2C.
In station A, the receiving side ring interface I2b of the normal line shown in Fig. 3 and the return switch +3b of the protection line have failed, that is, a new ring as shown in Fig. 2 C has been disconnected from the failure point @ of Fig. 5. Line (station A, -A, -A,
-A knee A,) is constructed. Incidentally, the separation of the station A may be performed by constructing a ring line using a bypass circuit Bp installed in advance to avoid the station A, as shown in FIG. 2d.

As a result of the foregoing, a ring line is configured in which the specific frame S2 is not received among the predicted failure areas, and the failure areas are separated from each other, and the network function is restored through this ring line.

Note that the method for configuring each ring line described above may be other than the method using the return request frame as described above (1
For example, each of the stations A1 to A4 may call back independently at fixed time intervals preset in a timer within each station.

(Effects of the Invention) In the ring line configuration method according to the ring network division method of the present invention, a specific frame S2 is sent to a station A immediately downstream of a fault location, or to a specific ring line H.
The expected failure points are roughly classified depending on whether or not the signal is received by station A1, so if it is received, only the failure point of that side is disconnected, and if it is not received, only the failure point of that side is individually disconnected. Since it is only necessary to separate the ring line, the network function using the new ring line can be quickly restored.

In particular, if a ring line is configured in which station A1 is disconnected when the specific frame S2 is not received by station A1, the network function can be restored even if a failure occurs in station A1, unlike the conventional system.

Moreover, there is no need to perform special disconnection control as in the conventional method, and the burden on software and hardware can be reduced accordingly, making it possible to reduce costs in implementation.

[Brief explanation of drawings]

Figures 1 a - d and 2 a - d are explanatory diagrams of the operation of the ring line configuration method of the ring network of the present invention, and Figure 3 is a block diagram of each station used in the same configuration method. An explanatory diagram of the configuration of a signal frame used in the configuration method, FIGS. 5a to 5d are explanatory diagrams of the operation of the conventional ring line configuration method of a ring network, and FIG. 6 is a block diagram of each station used in the configuration method, FIG. 7 is an explanatory diagram of possible line abnormalities. A I, Ax, A3. A1 is a normal line for station B, C is a protection line P is a configuration information S, is a failure notification frame S2 is a specific frame R is a specific ring line

Claims (2)

[Claims] (1) A plurality of stations A_1 to A_n are connected in a ring by a normal line B and a protection line C having transmission directions opposite to each other, and each station A_1 to A_n synchronizes the fault notification frame S_1 when an abnormality occurs on the normal line B. Send to normal line B,
Only the station A_1 that does not receive this fault notification frame S_1 continues to send out the same frame S_1, and each station other than the station A_1 stops sending out the fault notification frame S_1 from itself and receives the fault notification frame S_1 upon receiving the fault notification frame S_1. In a ring network in which the relative position of the station with respect to the station A_1 can be determined from the failure notification frame S_1 and the configuration information P of the connection order between the station and other stations stored in advance in each station, the station When A_1 determines that its own station is the station directly downstream of the failure point when an error occurs, it loops back its sending side for normal line B to protection line C, and returns the receiving side for normal line B to protection line C. A specific ring line R consisting of only the same station A_1 and a protection line C is configured, and the same station A_1 sends a specific frame S_2 to this ring line R, and the same frame S_2 is received by the own station via the same line R. A method for classifying failure points in a ring network, characterized in that expected failure points are broadly classified into cases in which failures occur and cases in which they do not occur. (2) In the ring network failure location classification method of claim 1, when the specific frame S_2 is received at the station A_1 via the specific ring line R, a plurality of failure locations expected at this time are identified. If a new ring line is configured that has been individually disconnected, and the specific frame S_2 is not received by the station A_1 via the specific ring line R, a new ring line that has been individually disconnected from the expected failure point is configured. 1. A method for configuring a ring line of a ring network, characterized in that it is possible to configure a ring line in which all predicted failure points are individually disconnected by these disconnections.