JPS61239744A - Control method for reconstitution of ring network - Google Patents

Abstract

PURPOSE:To eliminate the need for a centralized control station and to structure a high-reliability network by detecting the 2nd upstream station by the 1st station on the basis of connection position information stored previously when a ring system network becomes abnormal and indicating the return of a signal to the 2nd station. CONSTITUTION:A station ST which detects abnormality on an in-use transmission line 2 starts a waiting timer for abnormality information frame reception, and when the timer TI enters a time-out state without receiving an abnormality information frame BCN1, it is judged that the ST is an ST adjoining to a faulty downstream station in a faulty state, the 1st returning operation is performed to generate a BCN2 containing information showing an ST at the downstream side of the ST is an ST which performs the 2nd returning operation, and a waiting monitor timer T2 for the reception of the BCN2 is started to send out the BCN2. When the BCN2 is received before the timer T2 enters a time-out state, the 2nd returning operation is carried out at the next upstream ST to form a closed ring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a reconfiguration control method in a ring network, and particularly to a method suitable for constructing a new ring (degenerate ring) that bypasses a failure.

[Background of the invention]

As a failure countermeasure method for a ring network consisting of a dual ring consisting of an active ring and a standby ring, there is a method described in the following document, for example.

IEICE Techniques Vol, 84.1ia214.5E84-1
02 November 30, 1984 "Design and Characteristics of 100 Mb/s Loop Indoor Optical Transmission System" According to the above document, (1) When a network central control station (hereinafter referred to as C8) detects an abnormality in the transmission path, it A return instruction is issued to the managed station (hereinafter referred to as R8), and this is sent to both the active and standby rings. (2) Each R8 operates as a relay for the system that received the instruction, and performs a relay operation for the other system. (3) After receiving signals from both systems, R8 cancels the loopback, and only both R8s at the failed location maintain the loopback state.

The above method has the following drawbacks. In other words, it has a specific C8 that instructs a callback, and therefore a C8 failure!
Sometimes it becomes impossible to turn back. Although it is easy to consider having a backup station for C8, it is not a fundamental solution considering that this station will become an obstacle.

[Purpose of the invention]

An object of the present invention is to provide a reconfiguration control method in a ring network by equal distributed control of all stations (hereinafter referred to as STs) (STs operate with the same logic without providing a specific ST).

[Summary of the invention]

A ring network is a serial system. For this reason, even a single failure causes the communication function of the entire system to be lost, and all STs are notified of the ring abnormality. Countermeasures against failures in the ring network are taken using the above-mentioned characteristics.The ST that detects an abnormality sends an abnormality notification frame (
BCN), and when it receives a BCN, it relays the BCN, and if its own ST is in the process of sending BCN, it stops this. As a result, there is only one ST that continues to send BCN, and this ST is the only ST that should continue to take measures against the failure.
It can be identified as T.

As a countermeasure against failures in duplex rings, there is already known a method called loopback (loopback).

There are two types of transmission path loopbacks: the first loop (from the standby ring to the active ring) and the second loop (from the active ring to the standby ring in the opposite direction). When reconstructing, the above two types of folding must be done in pairs.

The problem of the present invention is how to perform equal distributed control of each ST to reconfigure the ring. Generally, in a ring network, only the active ring is used for normal communications. Considering that an abnormality in the standby ring alone does not affect normal communication, it is undesirable to reconfigure due to an abnormality in the standby ring. Therefore, the ring is reconfigured only when an abnormality occurs in the active ring. .

When a failure occurs in the active ring, each ST sends a BCN to inform the following of the abnormality as described above, and ultimately the only ST to continue troubleshooting is determined. As can be easily considered here, since the active ring in front of the ST is abnormal, the ST should perform the first loopback.

The ring reconfiguration is completed by further performing the second folding.

The present invention relates to how to perform this second fold. Here, the following condition is set: All STs connected to the ring recognize each other's upstream and downstream relationships, that is, the physical connection order according to, for example, the data transmission direction on the ring transmission path. Let us consider the reconfiguration of the ring under this condition. This condition can also be satisfied by, for example, artificially giving information to all STs at the time of system generation (initiation).

The problem with reconfiguring the ring is due to the unidirectional nature of the ring. In other words, the most upstream ST from the fault (the ST upstream of the fault)
is made aware that there is a fault immediately upstream by the above procedure, but the most downstream ST (i.e., the ST upstream of the frozen fault)
If this continues, T) will not be able to recognize that there is a problem immediately downstream. However, in a unidirectional serial system that has linear characteristics, the upstream and downstream relationships of each ST, ie, the relationship between one ST and the next upstream ST, are uniquely determined.

The ST that has performed the first loopback transmits the BCH containing information about the next upstream ST. Assuming that the BCN is received by all STs, the next upstream ST also receives the BCN and can recognize that there is a failure downstream of its own ST. Here, we will consider what kind of information each ST should have when the ring reconfiguration is completed by the ST performing the second turnaround.

In short, it is sufficient if the STs that correspond to the physical connection order on the ring transmission path can be grasped. For example, each ST may have an address used for normal communication corresponding to the order, or A unique number may be assigned to each ST and the number may be stored.

To reconfigure the ring using the above method, the second turn is □1
This depends on specifying the ST to perform, but it is necessary to consider the procedure in case the ST fails. The first loopback ST sends an instruction to the next upstream ST of its own ST to perform the second loopback, but if the next upstream ST is abnormal, the second loopback is not performed. If the ring does not recover within the time period, i.e., the ring does not reconfigure to form a closed ring (this can be determined by monitoring the ring-to-ring tour of the test frame), then the ST further upstream Send instructions to make a double turn. As a result, it is not a transmission line failure, but
Even if there is an abnormality in the active ring due to an ST failure, it is possible to form a closed ring that bypasses the failure.

[Embodiments of the invention]

FIG. 1 is a schematic diagram of a communication system implementing the present invention. In FIG. 1, 1-1. ... 1-b is a station (ST), 2 is an active transmission line, and 3 is a standby transmission line. Each ST is connected in a ring shape by a transmission line 2.3. The function of this system is to exchange or distribute data between each ST.

FIG. 2 shows the configuration of ST.

4 is a communication control mechanism, 5-1 and 5-2 are ring communication adapters, 6-1 and 6-2 are signal lines connecting the ring communication adapter and the communication control mechanism, and 7-1 and 7-2 are transmission path loopbacks. The signal lines 8-1 and 8-2 indicate return switches.The functions of the ring communication adapter are 1. Sending communication frames passed from the communication control mechanism to the transmission path, and capturing communication frames addressed to the own ST. It is to pass it to the communication control mechanism. There are two types of loopback of the transmission line: a first loop from the standby transmission line to the active transmission line, and a second loop from the active transmission line to the standby transmission line. The switch 8-2 is used for the first turn, and the switch 8-2 is used for the second turn. In particular, FIG. 2 shows the configuration in the first folded state.

FIG. 3 shows the structure of a communication frame using the configuration control of the present invention. In FIG.
: S D), 12 is a frame indicating the type of frame.
Control (Frame Control: F
C).

13 is the destination address (Destination Add
ressss: DA).

14 is the source address.
:SA).

15 is exchange information (Infor*ation: IN
FO), 16 is the frame check sequence (F
rame CheckSequence: F CS
), 17 is an end delimiter ([End Delimiter: ED) indicating the end of the frame, INFOI 5 is the information type of 18 (Vector
In this embodiment, the next frame of configuration control is used.

If FCl2 is 1 byte of information, then F C12: B '0100100G' (First configuration control notification: BCNl) F C12: B '01001
001' (Second configuration control notification: BCH2) Frames used for purposes other than configuration control notification use FC values other than the above.

Both BCNI and BCH2 are sent to the active transmission line.

In particular, BCH2 includes information on the ST in which the second loopback should be performed. In other words, information type 18 is second return S.
The information value 19 indicates the storage of T information, and the information value 19 includes the address of the ST where the second loopback should be performed. Note that DA13 is addressed to all STs. INFOI 5 can include a transmission serial number, etc., but is not used in this embodiment.

FIG. 4 shows the operation flow of ST when reconfiguring the ring.
In particular, the operational flow when sending BCNI and BCN2 is shown. The ST that detected an abnormality in the active transmission line 2 is the BCN.
Start the timer (T1) waiting to receive I (too)
, sends BC:N1 (101), If BCNI is received before Tl timeout, determines that the own ST is not an adjacent ST downstream of the failure and ends this operation flow (102), Receives BCNI If T1 times out without doing so, the local ST is judged to be the ST adjacent to the downstream side of the failure 103), and the first loopback is performed 104).
Form a BCN2 that includes information indicating that the next upstream ST of T is the ST that should perform the second loopback (105), BCN2
Start the reception wait monitoring timer T2 (106), BCN2
(107), BCN2 before T2 timeout
If T2 is received, it is determined that the second turnaround has been performed at the next upstream ST and a closed ring has been formed, and this operation flow is ended (108).On the other hand, if T2 times out (109), It is determined that the second turnaround at the ST has failed, and a BCN2 is formed in which the next upstream ST of the ST is the second turnaround ST (110), and the above operation is repeated. For example, it holds physical connection arrangement information on the current transmission path, and the second return ST is specified according to this information.
Can be set at generation time.

FIG. 5 is an operational flow when BCN2 is received.

Check whether the own ST is the ST that should perform the second loopback (200), and if the second loopback is to be performed, perform this (201).The ring is reconfigured by the above procedure.

〔Effect of the invention〕

According to the present invention, by equal distributed control of all STs,
For example, configure a ring (data transmission path) that bypasses a failure (
specific ST (for example, centrally managed ST).
), and has the effect of building a highly reliable network.

[Brief explanation of the drawing]

Figure 1 is the overall configuration of the communication system, Figure 2 is the configuration of the station (ST), Figure 3 is the configuration of the communication frame, Figure 4 is the configuration control, especially the operation flow on the active side, and Figure 5 is the configuration of the communication system.
The figure shows the operational flow of configuration control, especially the passive side. Fig. 4 103-105... Performs the first loopback without receiving BCN, 1, and performs the second loopback to the next upstream ST (operation to form BCN2, 109-110...
Operation of forming BCN2 to make a second return to the next upstream ST without receiving BCN2, Fig. 5 200-20
1... Own ST makes the second turn 1st Figure A 2 Figure 3

Claims (1)

[Claims] 1. Connecting a plurality of stations to a working ring transmission line and
In a ring network connected in a ring shape by a standby ring transmission line provided in parallel, each station stores in advance information corresponding to the physical connection position of other stations on the transmission line, and When an error occurs in the ring network, each station sends the first signal to the active transmission line, and only the first station that does not receive the first signal from the active ring transmits the first signal from the standby transmission line to the active transmission line. The first station returns the signal to the transmission path, detects the second upstream station based on the pre-stored connection position information, and waits for the second station from the active transmission path. 1. A reconfiguration control method in a ring network, characterized by transmitting a second signal instructing return of a signal to a system transmission path. 2. In paragraph 1, when the first station does not receive a response signal to the second signal, the first station connects a third station further upstream than the second station based on the pre-stored connection information. 1. A reconfiguration control method in a ring network, comprising: detecting the signal and transmitting a third signal instructing the third station to return a signal from the active transmission line to the standby transmission line.