JPH0685530B2 - Network localization system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a star (radial) data exchange network, and more particularly to a method of searching (localizing) an abnormal portion suitable for a failure countermeasure when a transmission line is abnormal.

[Background of the Invention]

The configuration of the network targeted by the present invention is a star ring topology as shown in FIG. In FIG. 1, 1 is a general station (ST), 2 is a management station (management ST) for controlling the network configuration, 3 is a concentrator, and 4 is a data transmission path (hereinafter referred to as a ring).

Conventionally, the following failure location localization methods are already known in ring networks. Each ST sends a ring abnormality notification frame (hereinafter referred to as Beacon) when it detects an abnormality in which data (or communication frame) cannot make a round in the ring. When it receives Beacon, it stops sending Beacon. As a result, only one ST immediately downstream of the fault continues to send Beacon, and the fault location can be localized. Using this function, consider a failure countermeasure by controlling network configuration.

In FIG. 2, reference numeral 7 is a switch (hereinafter referred to as a port) for connecting ST1 to the concentrator 3. Port 7
It is a switch for incorporating ST1 into a ring network (hereinafter referred to as a ring), and is also a unit for the concentrator 3 to disconnect ST1 from the ring (hereinafter referred to as a bypass). Dotted line 6 is the flow of Beacon.

When obstacle 5 occurs in Fig. 2, ST immediately downstream of obstacle 5
Only 1-D keeps sending the Beacon. Admin ST2 Beac
The transmission source ST1-D is known from the information in on, and the port 7-D to which the ST1-D is connected is bypassed. As a result, the failure is separated from the ring and communication is possible between the remaining STs. In FIG. 2, there is one ST per port, but the same can be considered when a plurality of STs are connected per port.

Next, consider the case where ST1 freely moves the port. In this case, it becomes difficult to specify the port to be bypassed. That is, in the above example, the port 7-D is bypassed because it is known that the ST1-D is connected to the port 7-D. If the ST1-D is connected to any port, If it is not known whether or not there is a bypass, it is not possible to identify the bypass location, and therefore, there is a problem that failure countermeasures cannot be taken. Considering that each ST freely moves between ports,
The first issue is how to specify the port to be bypassed.

Regarding the above-mentioned problem, a countermeasure method based on the following documents is already known.

Draft "Token Ring Architecture for Local Area Networks" contributed to the IEE 802.5 Project on Local Area Networks, March 8, 1982, Dee Andrew Andrews, Gee De Schultz (Contribution of work
ing papers to IEEE Project 802 on Local Area Netwo
rks, March 8,1982 “A Token Ring Architecture for Lo
cal-Area Networks "By DWAndrews, GDSchultz) Here, the Beacon sends the port identifier, that is, the port number, that is, ST is informed of the port number when connecting to the port. Regarding the method, for example, a patent published by IBM (Japanese Patent Laid-Open No. 58-1
17750).

According to the above literature, the port to be bypassed can be specified as follows.

In the above example, the management ST2 extracts the port identifier from the received Beacon. In this example, it is port 7-D. By bypassing the port 7-D, it is possible to take measures against the failure of the ring and restart the communication of the remaining ST.

The previously known method has been described above. However, these methods have the following drawbacks.

1. If you misconfigure the port identifier, you may not be able to permanently bypass the failed port.

2. A special mechanism (device) is required to notify the ST of the port identifier.

3. A single bypass does not necessarily mean that countermeasures for failures are completed.
For example, if a failure occurs between the ST transmission end and the concentrator 3, the ST connected to the next downstream port of the failure port
Beacon is sent. As a result, the first bypass is performed on the next downstream port which is normal.

[Object of the Invention]

An object of the present invention is to provide a method for locating a failure point in a Star-Ring network without requiring special equipment.

[Outline of Invention]

Since the ring network is a serial system, it is easy to localize the fault. In addition, the star configuration network is highly maintainable because it allows centralized maintenance. In order to improve the reliability of the network system, a star ring network having these features is suitable.

The basic idea of identifying a failure location for network reconfiguration in the event of a network failure based on the present invention is to actively cause (pseudo) failures. In other words, a pseudo fault that produces the same effect as an actual fault (a pseudo fault in the sense of intentionally causing it) is generated, and changes in abnormal states due to the pseudo fault are monitored. It is characterized in that the actual failure location is specified (localized) based on this change.

Abnormality detection and abnormality notification (other ST autonomous) judgment (others)
In a network composed of STs having a function of performing (to ST), an ST in a non-abnormality detection state can be newly set to an abnormality detection state by changing the location of a failure (including a pseudo failure). The present invention particularly applies this property to a ring-structured network having characteristics as a serial system. That is, if the abnormality detection ST fluctuates due to a false failure intentionally caused, it can be determined that there is an actual failure location near the upstream of the ST.
If a pseudo fault occurs upstream from the actual fault location,
Although the abnormality detection ST may fluctuate, the fluctuation cannot be grasped from a specific one point (management ST) because the ring is blocked by an actual failure.

Example of Invention

 Examples of the present invention will be described below.

In FIG. 3, 6 is data (or communication frame)
Flow (indicated by a broken line), 7 (7-A, 7-B, 7-C) is a port, and 8 (8-A, 8-B, 8-C) is a signal line for changing the connection state of the port. Is. Incidentally, P indicates an example of a failure described later.

FIG. 4 shows the connection state of the ports. a is a normal connection, b is a bypass, and c is a released state. In the released state c, the data flow 6 is interrupted.

FIG. 5 shows the structure of the frame described in the description of this embodiment. 10 is Start Delimiter: SD
(Start of frame) 11 is a frame control (Frame
Control): FC (indicates the frame type), 12 is the destination address (Destination Address): DA (destination address), 13 is the source address (Source Addess): SA
(Source address), 14 is information (Informa
tion): I and 15 are frame check sequences (Frame Che
ck Seaquence): FCS, 16 is the End Delim
iter): ED (end of frame). The information 14 may be omitted. Also, DA1
2 is a broadcast address addressed to all STs. In this embodiment, the following two types of frames are used.

Beacon: Frame for ring abnormality notification Purge: Frame for sweeping unnecessary data on the ring The above frames can be distinguished as follows. Note that FC11 is 1-byte (8-bit) information.

FC11 = 10100001: Beacon FC11 = 10100010: Purge FIG. 6 shows the operation of the ST already known in the following literature, for example.

Draft EEE EEE 802.5 Standard “Token Ring Access Method and Physical Layer Specification” Working Draft 19
December 1, 1983 (Draft IEEE Standard 802.5 “Token Ring Access Method and Physical Layer Spec
ifications "Working Draft December 1,1983) In other words, the ST that is in the state of monitoring the normality of the ring (normal mode) detects Beacon until the next state when it detects an abnormality in the ring.
Continue to be sent.

(I) When a Beacon sent by an ST other than the own ST is received,
Returning to the normal mode, the ring normality monitoring state is again established. In other words, the fault is considered to be upstream of the ST upstream of the own ST.

(Ii) When the Beacon sent by the local ST is received, it is considered that the abnormality has been recovered (the faulty part has been separated from the ring),
After sending Purge for a certain period of time to remove Beacon on the ring, the normal mode is entered.

FIG. 7 shows a flowchart of the ring failure countermeasure procedure of the management ST2. The procedure for identifying a faulty port when a fault P occurs between the transmitting end of ST1-B in FIG. 3 and the port 7-B will be described below with reference to FIGS. 3 and 7. In this case, only ST1-C will continue to send Beacon after a fixed time.

When the management ST receives the Beacon and learns that an abnormality has occurred in the ring, it first sends the most upstream (next downstream of the management ST) port 7-
A is released via signal line 8-A (steps 701, 702,
703). (Hereinafter, the meaning of upstream and downstream is equivalent to the direction in which data is transmitted. That is, it is assumed that data is transmitted from upstream to downstream. Further, the management ST2 is the most downstream point of the ring.) Port 7- Even if A is released, the state (ring abnormality notification state) does not change because the fault is related to port 7-B, and the management ST2 continues to receive the same Beacon. Next, the management ST2 releases the next downstream port 7-B (steps 704, 705, 703). This result is the same as the above, and the state does not change. Management ST2 is further downstream port 7
-C is released (steps 704, 705, 703). As a result,
The management ST2 becomes the Beacon transmission source ST (the general ST and the management ST are the same regarding the Beacon transmission function), and the Beacon transmission source ST changes. The management ST2 bypasses the port 7-C released this time (step 706). Further, the ports 7-A and 7-B in the released state are normally connected (steps 707 and 708). (For example, if port 7-
If it is between C and the ST1-C receiving end, the abnormality of the ring will be recovered here. However, in this embodiment, since the failure is assumed in the portion (P) requiring further control, the abnormality of the ring cannot be recovered. The management ST2 sets the bypass of the port 7-C to the normal connection and the next upstream port 7-B of the port 7-C to the bypass because the ring abnormality is not recovered (steps 709, 710, 711). As a result, the ring abnormality is recovered. With the above procedure, it is possible to identify the abnormal port and automatically implement the failure countermeasure for disconnecting the failure point from the ring. Note that FIG. 7 does not consider double failure.

It is easy to consider a method of performing collective bypass or collective release in order to specify the abnormal port. That is, a part of
This is a method in which all ports are bypassed or released, and then the ports are incorporated into the ring according to a predetermined fixed rule. In any case, however, the abnormal port is identified by using the fluctuation of the Beacon transmission source ST, that is, the fluctuation of the abnormal phenomenon, which is caused by the active failure (controlling to mimic the failure). To the extent, it is only one application of the invention.

〔The invention's effect〕

According to the present invention, it is possible to identify a port that is in an abnormal state even under the conditions of ST free (arbitrary) ring incorporation, disconnection, and movement, so that it is possible to take measures against ring (network) failures. There is.

Further, according to the present invention, since it is not necessary for each ST to be aware of “where the relevant ST is connected to”, the failure countermeasure by setting the information for port identification to be notified to the ST Has the effect of eliminating the problem of being disabled, and a special mechanism (device) for notifying the ST of the identifier.
There is an effect that the quantity of products can be reduced by eliminating the requirement.

[Brief description of drawings]

FIG. 1 is a diagram showing a Stirling network, FIG. 2 is a diagram showing a data flow at the time of failure, FIG. 3 is a diagram showing a network to which the present invention is applied, and FIG. 4 is a port connection state. FIG. 5, FIG. 5 is a configuration of a communication frame used in the embodiment of the present invention, FIG. 6 is a diagram showing an operation example of an ST when a network is abnormal, and FIG. 7 is a flowchart of a failure countermeasure procedure in the management ST. .

Claims (3)

[Claims] 1. A ring-shaped transmission line having a predetermined signal transmission direction, and a plurality of stations each of which is incorporated into the ring-shaped transmission line via a port and sends out a ring abnormality notification signal when a ring abnormality is detected. When a ring abnormality occurs, a management station that performs a configuration control operation to disconnect the faulty part, and a state in which the ports of each station are normally connected to the above transmission lines, while maintaining the signal flow in the above transmission lines A ring error in a network consisting of a plurality of switch means for releasing the port from the transmission line or releasing the port from the transmission line to release the signal flow at that point. Eventually, a specific station adjacent to the abnormal location on the downstream side in the signal transmission direction will eventually detect the ring abnormality. When the ring abnormality occurs, the management station keeps sending a signal, and when the ring abnormality occurs, the switch means is selectively released to cause a pseudo fault in the ring transmission line to notify the ring abnormality. A network failure point localization method characterized in that the above failure point is localized based on the change situation of the station where the signal is generated. 2. When a ring abnormality occurs, the management station sets the switch means to a release state in a predetermined order regardless of the station position where the ring abnormality notification signal is generated. The method for localizing a network failure point according to claim 1, wherein the failure point is localized by detecting that the station that is the source of occurrence has been replaced. 3. When a ring abnormality occurs, the management station releases the switch means one by one in a predetermined order, and when the n-th switch is released, the station which generated the ring abnormality notification signal. When the n-th switch is replaced, the n-th switch is returned to the connected state and the n-1-th switch is set in the bypass state to disconnect the faulty part from the ring. Method.