JP3302248B2 - Transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission system, for example, a plurality of SDH (Synchronous).
Digital Hierarchy) lines are accommodated, one of them is used as a working system, and any of them is used as a spare system.

[0002]

2. Description of the Related Art Conventionally, an SDH accommodating an SDH line
In the apparatus, an SDH control method using a standby switching function is applied for the purpose of improving network reliability and maintenance operability. Such a technique is disclosed in, for example, the following document.

Reference: Telegraph and Telephone Technical Committee TTC Standard 19
1993, "Vol. III, First Volume, Inter-Network Interface (Inter-Network Transmission Method)", "III-I-G.G783",
"Operation of alarm system and switching system of SDH multiplex converter".

FIG. 2 shows an example of a switching operation flowchart of a 1 + 1 configuration / bidirectional operation / non-return mode system.
Have . In FIG. 2, between the SDH device 1 and the SDH device 2 facing the SDH device 1, a signal failure of the working section 2 is determined from the state of no request for selecting the working section 2 by S
When the detection is performed on the DH device 1, a series of switching operations as described below are performed.

That is, a. The SDH apparatus 1 notifies the SDH apparatus 2 of a signal failure (SF).

B. After receiving the signal failure (SF), the SDH apparatus 2 performs selection switching to the backup section 1 and notifies the SDH apparatus 1 of an acknowledgment (RR).

C. After receiving the acknowledgment (RR), the SDH device 1 performs selection switching to the spare section 1.

D. The SDH device 1 monitors the state of the working section 2 and, upon confirming the recovery, notifies the SDH device 2 that the device is waiting for recovery, and notifies that there is no request (NB) after a lapse of a predetermined time.

E. SDH apparatus 2 completes the switch receives no request (NB), becomes the working section 1 selected state indicates that it is no request to the SDH apparatus 1 (NB).

F. No request in SDH device 1 (NB)
Complete switching reception becomes a working section 1 selected, you series of switching operation is completed. The above is for the standby switching function
Although our Keru which is an example of a switching operation, in such a SDH device if switching factor such as the signal failure occurs, opposed S
The switching operation is performed by handshaking with the DH device.

[0011] Figure 3 shows the structure of a traditional SDH equipment, SDH device, and the function block A which performs SDH interface termination, and a function block B of switching control
Have .

In the conventional SDH apparatus, when the switching control section of the function block B is initialized during the switching operation due to a factor such as a restart of the apparatus, the switching state stored in the function block B disappears, and independently initial state and switching state of the apparatus (e.g., the working section 1 without selection request state) Ru are carried device launch from.

[0013]

However, since this switching control is performed by handshaking between the opposing SDH devices, if the switching state is changed during the switching operation, there is a risk that the switching cannot be performed normally. there were.

FIG. 4 shows an example of a switching operation flowchart when the switching operation cannot be performed normally . FIG.
In, for example, the SDH device 1 and the S
In the DH device 2, when the SDH device 1 detects a signal failure of the working section 2 from the state of no request for selecting the working section 2, the following operation is performed.

A. The SDH apparatus 1 notifies the SDH apparatus 2 of a signal failure (SF).

B. After receiving the signal failure (SF), the SDH apparatus 2 performs selection switching to the spare section 1 and notifies the SDH apparatus 1 of an acknowledgment (RR).

C. After receiving the acknowledgment (RR), the SDH device 1 performs selection switching to the spare section 1.

Here, immediately after the signal failure of the working section 2 is restored, it is assumed that the function block B, which is the switching control unit of the SDH apparatus 1, has been initialized by a reset signal due to factors such as a restart of the apparatus. Then, the SDH apparatus 1 is started up, for example, from an initial state in which there is no active section 1 selection request.

As a result, the SDH apparatus 1 is in a state of "no request for selection of the current section 1", and the SDH apparatus 2 is in a state of "switching the selection of the spare section 1". However, there is a problem that the switching state transition cannot be performed.

From the above, the SDH apparatus 1 and S
When performing a switching selection transition between working and protection sides between DH device 2, given a reset signal to the functional block B to perform the switching control functions, stored contents are initialized erased In addition, there is a demand for a transmission system capable of performing a switching operation efficiently and with a simple configuration continuously from a state before initialization.

[0021]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a first method.
At least the first line and the second line are connected in parallel between the transmission device and the second transmission device, and the first transmission device includes a line termination circuit for the first line, The line termination circuit for the second line and which of these line termination circuits are to be selected as the active system and which of them is switched as the standby system are determined.
A control circuit for initializing the control state of the switching selection by a reset signal. The second transmission device also includes:
A line terminating circuit for the first line, in a transmission system comprising a line termination circuit for the second line, as follows
Was it also to the.

[0022] and the line termination circuits for the first line of the first transmission device, line termination circuit and a pixel respectively for the second line, and a communication switching state between the second transmission device A "storage means" is provided for non-volatilely storing the switching state transition information representing the communication transition state, and the switching state transition information is given to the control circuit and is stored in a volatile manner.

The control circuit of the upper Symbol first transmission device, when the reset signal is applied, and the storage means of line termination circuits for the first line of the first transmission device, the second so read the switching state transition information stored in the above storage means of the line termination circuits for line, judging from the switching state transition information, that Re given et <br/> said reset signal a line terminating circuit for the first line of the control to be in front of the switch selected said first transmission device, intends row for a line termination circuit for the second line. By adopting such a configuration, even if the reset signal is given to the control circuit,
A line terminating circuit for a first line of the first transmission device;
In the line termination circuit for the line, the switching state transition information indicating the communication switching state and the communication transition state before the reset is stored by the respective storage means, so that the control circuit stores this switching state transition information. Use before reset state
Determine status, and line termination circuit for the first line of the first transmission device, the reset signal to the switching selecting state before the images given to the line termination circuits for the second line control intends line. Therefore, the line termination circuit for the first line and the line termination circuit for the second line of the first transmission device are:
By selection control from the control circuit, the switching state of the line termination circuit for the first line and the line termination circuit for the second line of the second transmission device is set to a state before resetting , and the operation is resumed. can do.

[0024] Therefore, when performing a switching selection transition between working and protection sides between the first transmission device and second transmission devices, the reset signal is supplied to the control circuit for executing switching control function Even if the memory contents are erased and initialized,
Efficiently yet a switching operation continuously from the initialization state before, Ru can be performed with a simple configuration.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. In the SDH switching control method according to the present embodiment, in a device that provides a standby system switching function in a line interface device such as an SDH device, a backup memory circuit that accumulates failure information and switching state transition information is provided in a line termination unit. , the switching control unit by reading the switching state from the backup memory circuit be initialized, and can continue the switching state transition before initialization
Was .

The fault information includes, for example, a terminal station section alarm display signal MS-AIS (Multiplex).
S ec tion Alarm Indication
Signal), LOF (Loss) out of frame
Of Frame), LOS (Los s Of)
Signal failure SF (SignalF) such as Signal
aile), signal degradation SD (Signal Degrad)
e) and the like.

FIG. 1 is a configuration diagram of an example of the SDH transmission system. In FIG. 1, the SDH transmission system includes:
SDH device 1A are connected by SDH line of the active system and a standby system, consists SDH device 2 which, when viewed rather large
Although construction of the not the same as the conventional configuration, SDH apparatus 1A
The internal configuration has been improved.

The SDH apparatus 1A includes a functional block Aa, a functional block Ab, and a functional block Ba for realizing a switching control function, which are improved as compared with the related art. The functional block Aa includes a backup memory circuit 21 including a backup RAM for holding the autonomous switching transition state and the failure state in a nonvolatile manner, and implements a terminal section termination section of the SDH interface. Function blocks Ab, similarly to the above Symbol function block Aa, includes a configured backup memory circuit 22 autonomous switching transition state or failed state backup RAM for holding non-volatile manner, the terminal station section termination of SDH interface Is realized.

The function block Ba is an end station section spare switching unit is constituted by a microprocessor circuit 31 performs a switching control against the functional blocks Aa, the Ab. The function block Ba is provided with a function block Aa, especially in order to continuously perform switching without inconsistency when a system reset signal is supplied from a higher-level device.
The switching control operation is performed on the functional blocks Aa and Ab using the switching state transition information and the failure information backed up in Ab.

For this reason, the microprocessor circuit 31
Is composed of a microprocessor, a program ROM, a working RAM, and an interface circuit,
A program for performing a switching operation is mounted on the program ROM to perform the above-described switching control operation.

In FIG. 1, a functional block Ba of the SDH apparatus 1A has an SD block facing the functional blocks Aa and Ab.
When a failure in the interface with the H device 2 is detected, or in response to a switching request from an external (upper) / opposite device, the switching priority is taken into account, and the opposing SDH device 2
And switching control.

At this time, the state of the switching control is sequentially changed to the backup memory circuit 2 in the functional blocks Aa and Ab.
1 and 22. Here, if the given reset signal to the functional block Ba switching control functions by some kind of factors has been initialized, for switching state stored in the function block Ba disappears, during start-up of the functional blocks Ba , the function block Aa, reads the switch status and fault conditions from Ab internal backup memory circuits 21 and 22, Ru is continued switching control. FIG. 5 is a switching operation flowchart for explaining the switching operation which is a feature of the present embodiment. In FIG. 5, for example, between the SDH device 1A and the SDH device 2 facing the SDH device 1A,
Working from the working section selection request dental status section 2
a is detected on the SDH apparatus 1A side (step S
If the 3) was, it intends row the following operation. a. First, the SDH apparatus 1A notifies the SDH apparatus 2 of a signal failure (SF) (step S4).
“Storing failure information / switching state transition information in the backup memory circuits 21 and 22” in the function blocks Aa and Ab (Step S4).

B. Next, in the SDH apparatus 2, a signal failure (S
After reception of F) , selection switching to the spare section 1b is performed, and an acknowledgment (RR) is notified to the SDH apparatus 1A (step S5).

C. Then, the SDH apparatus 1A, after receiving the acknowledgment (RR), performs selection switch to the spare section 1 a, accumulates the switching state transition information function block Aa, the backup memory circuit 21 and 22 in the Ab .

Immediately after the signal failure of the working section 2 is restored, a reset signal is sent to the functional block Ba, which is the switching control function unit of the SDH apparatus 1A, due to a factor such as a restart of the apparatus from the host apparatus. given the operation of the microprocessor circuit 31 is initialized, the data relating to the switching operation which has been stored in the working RAM is Ru erased so far (step S7).

By this initialization, the SDH apparatus 1A
Backup memory circuit 2 in functional blocks Aa and Ab
The failure information / switching state transition information stored in Nos. 1 and 22 is read (step S7a). Here, as the switching state transition information, “during selection of the spare section 1a” is read from the backup memory circuits 21 and 22 and supplied to the microprocessor circuit 31 of the functional block Ba.

The microprocessor circuit 31 of the functional block Ba controls the switching of the functional blocks Aa and Ab determined from the read fault information and switching state transition information.

D. Then, the SDH apparatus 1A monitors the state of the working section 2a, and when the
Notifying the device 2 that it is waiting for recovery (step S
8) Then, after a lapse of a predetermined time, a notification of no request (NB) is notified (step S10).

[0039] e. In S DH apparatus 2, No Request (NB)
Is received, the switching is completed, the working section 1b is selected, and there is no request to the SDH apparatus 1A (NB).
Is notified (step S11).

[0040] f. In the SDH apparatus 1A, there is no request (N
By receiving B), it becomes the working section 1a selected state, that it has completed the transition notifies the functional block Ba, you these series of switching operation is completed. Thereby, the SDH device 1A and the SDH device 2 are in the non-recovery mode,
Section 1a as an active, Ru is switched to be used in selecting and 1b. As described above, in the above-described switching control method, function block Ba which performs switching control is initialized by the reset signal generated by the system reset during switching operation, even disappears switching transition state information from the microprocessor circuit 31, initial Ru can be performed switching operation to continue from of the state before. (Effects of the embodiment of the present invention): According to the SDH switching control method of the SDH transmission system of the embodiment of the present invention, the switching control is performed even when the function block Ba as the switching control unit is initialized. Can be continued. Therefore, there is an effect that an SDH transmission system excellent in network reliability and maintainability can be realized.

[0041] More specifically, when performing a switching selection transition between working and protection sides between the SDH devices 1A and SDH device 2, a function block Ba to perform switching control function <br/> reset signal is given, even stored contents are initialized erased, efficiently yet a switching operation continuously from the initialization state before, Ru can be performed with a simple configuration. In addition, the backup memory circuits 21 and 22 store fault information in addition to the switching state transition information .
The functional block Ba controls the switching to the switching transition state before the reset in consideration of the failure information, as well as the functional blocks Aa and Ab.
Can be done against

(Other Embodiments) (1) In the above embodiment, an example is described in which the present invention is applied to the standby switching function in the SDH apparatus in the 1 + 1 configuration / bidirectional operation and non-return mode. By configuring a line interface device with a line termination unit provided with a backup memory circuit for storing fault information and switching state transition information and a switching control unit, a line in a network that provides a standby switching function other than the above-described embodiment. Apply the present invention to interface devices
It is Ru can. Further, as switching between the active system and the standby system, it is possible to cope with any operation of the return mode and the non-return mode.

(2) In addition, as the SDH line, STM
(Synchronous Transfer Mod
e: synchronous transfer mode) -level 0 (51.84 Mbit)
/ S), -level 1 (155.52 Mbit / s),-
Level 4 (622.08 Mbit / s), -Level 16
(2488 Mbit / s), -Level 64 (10 Gbi
t / s) and the like, and can also be applied to other transmission lines.

(3) Further, the number of the above-mentioned transmission lines is not limited to two. Even if the number is three or more, any one of the transmission lines is selected as the active system, and the remaining transmission lines are selected as the standby system. Even in this case, the above-described configuration can be similarly applied.

[0045]

As described above,,The present invention provides a first transmission
At least a first line between the device and the second transmission device;
The second line is connected in parallel, and the first transmission device includes:
A line termination circuit for the first line and a line termination circuit for the second line
The terminal circuit and any of these line termination circuits
To switch and select which to switch to the standby system.
Then, the control state of this switching selection is initialized by the reset signal.
And a control circuit for resetting the second transmission device.
A line termination circuit for the first line and a line termination for the second line
A transmission system comprising: a first transmission device;
A line termination circuit for the first line and a line for the second line
The terminating circuit disconnects communication with the second transmission device.
Switching status and communication transition status as switching status transition information
Storage means for storing data spontaneously and switching to the control circuit.
The first transmission
When the control circuit of the device receives the reset signal,
Termination circuit for the first line of the transmission deviceStorage means
And a line termination circuit for the second circuitOn the roadStorage meansWhenRemembered
Read the switching state transition information
Judging from the state transition information, the reset signalToPrevious
Control to make the switching selection state of the first transmission apparatus of the first
Line termination circuit for line and line termination circuit for second line
And what to do.

Therefore, the present invention adopts such a configuration to allow the first transmission apparatus 1 and the second transmission apparatus to perform switching selection transition between the active system and the standby system. Even if a reset signal is given to the control circuit of the first transmission device that executes the switching control function and the stored contents are erased and initialized, the switching operation can be efficiently performed continuously from the state before the initialization. Moreover, Ru can be realized transmission system that performs a simple configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an SDH transmission system according to an embodiment of the present invention.

FIG. 2 is a flowchart of a conventional switching operation between an active system and a standby system.

FIG. 3 is a configuration diagram of a conventional SDH transmission system.

FIG. 4 is a flowchart illustrating a problem of a conventional switching operation.

FIG. 5 is a flowchart of a switching operation according to the embodiment.

[Explanation of symbols]

1A, 2 ... SDH device, 21, 22 ... backup memory circuit, 31 ... Microprocessor circuit, Aa, Ab,
Ba: Functional block.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Ono 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. No. Nippon Telegraph and Telephone Corporation (72) Inventor Masahiko Takaya 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Tokuo Tashiro 3--19 Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Inside Nippon Telegraph and Telephone Corporation (72) Inventor Ken Sanbe 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (56) References JP-A-3-216048 (JP, A) JP-A-63-67051 (JP, A) JP-A-6-233365 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 29/14 G06F 11/00 310 H04L 1/22

Claims (3)

(57) [Claims] At least a first line and a second line are connected in parallel between a first transmission device and a second transmission device, and the first transmission device is connected to a first line. a line terminating circuit of use, and line termination circuit for the second line, the one of these line termination circuit and the active system to determine whether to <br/> switch selects one as the standby system, the reset signal A control circuit for initializing the control state of the switching selection by the second transmission device. The second transmission device also includes a line termination circuit for the first line ,
In a transmission system including a line termination circuit for a second line, a line termination circuit for a first line of the first transmission device,
A storage means for non-volatile storage of communication switching state and switching the state transition information representing a communication transition state between said second line termination circuits and Waso respectively for line, the second transmission device At the same time, the switching state transition information is given to the control circuit and stored in a volatile manner. When the reset signal is given, the control circuit of the first transmission device receives the first state of the first transmission device. and the storage means of the line termination circuit for line and to read out the switching state transition information stored in the above storage means of the line termination circuits for the second line, from the switching state transition information it is determined, the first control to the switching selection state before the reset device signals is given the first transmission device
And a line termination circuit for the second line and a line termination circuit for the second line. Wherein the said memory means of line termination circuits for the first line of the first transmission device, the a second line termination circuits of the memory means for line, even further fault information A line for the first line of the first transmission device to be stored.
The terminating circuit and the line terminating circuit for the second line are
Respectively, give also the fault information to the control circuit, the control circuit, judging from the above switching state transition information and the failure information, the control to the switching selection state before the reset device signals is given a line terminating circuit for the first line of the first transmission device, No in claim 1 serial <br/> mounting which is characterized in that with respect to a line termination circuit for the second line Transmission system. 3. The first line and the second line are SDH lines, and the line termination circuits of the first transmission device and the second transmission device are terminal station section termination circuits. There, the control circuit, the transmission system according to claim 1 or 2, characterized in that an end station section switching circuit.