JP2002164907A - Path route changeover device and path protection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a path route changeover device that can properly conduct 2-way changeover of a path route. SOLUTION: On the occurrence of a fault in a reception path 4a, a path alarm detection section 12a detects a path alarm and gives a detection signal to an adder section 14a and a RDI(Remote Defect Indication) insertion section 15a. The adder section 14a gives a switching signal to a path switch section 11 to allow the pass switch section 11 in response to the switching signal to switch the reception path 4a to a reception path 3a. Furthermore, the RDI insertion section 15a receiving the detection signal similarly to above inserts a signal with a RDI bit set thereto to a transmission signal. On the other hand, when a RDI detection section 23b detects the RDI bit from the transmission signal circulated through a transmission path 4b, the section 23b gives the detection signal to an adder section 24b. The adder section 24b gives a switching signal to a path switch section 21 and the path switching section 21 in response to the switching signal switches the path route from a transmission path 24b to a transmission path 3b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a path route switching device in SDH transmission and the like, and in particular, reduces the development burden of hardware and software (firmware) by making a small change to an existing path route switching device. In addition, the present invention relates to a path route switching device and a path protection method capable of appropriately performing bidirectional switching of a path route.

[0002]

2. Description of the Related Art Conventionally, SDH (Synchronous Digita)
l Hierarchy) In SDH transmission for transmitting a multiplexed signal or the like, a standby path is prepared in advance in preparation for a failure in the active path, and when a failure occurs in the active path, a path route to the standby path is established. A path protection method for switching the password is used. Such switching of the path route is generally performed by a path route switching device. Specifically, the path route switching device receives the STM-N (synchronous transmission module level N (N = 1,
4, 64)) The signal is monitored, and when a path alarm is detected from the STM-N signal, the route of the reception path is switched to another path. The path alarm is generated when a failure such as a disconnection occurs in the path.

[0003] As described above, the path route switching device provides
Since the switching of the path route is automatically performed, a failure can be appropriately avoided, and the reliability of data transmission can be improved.

[0004]

Generally, the above-described conventional path route switching apparatus performs monitoring on the reception paths of the opposing nodes, and sends the STM-N to each other.
When a path alarm is detected from the signal, only the detected reception path switches the path route to another reception path. Therefore, there is a possibility that different routes are selected on the receiving side and the transmitting side of the path route switching device due to the switching of the path route. In such a state, there is a possibility that a maintenance worker or the like may be confused when the failed path is maintained.

Recently, in such a case, an ITU-T (International Telecommunications U) has been developed so that a bidirectional path can be simultaneously switched to the same route.
nion -Telecommunications Standardization Sector)
Recommendation G. At 841, a method of exchanging K4 bytes of path overhead is proposed.

However, according to ITU-T Recommendation G. 841
The method proposed in (1) newly defines a path overhead K4 byte, and is realized by a device that has detected a path alarm by transferring this path overhead K4 byte to an opposing device. Firmware) had to be changed on a large scale.

The present invention has been made in view of the above situation, and by making a small-scale change to a current path route switching device, it is possible to reduce the development load of hardware, software (firmware), etc. An object of the present invention is to provide a path route switching device and a path protection method that can appropriately perform bidirectional switching.

[0008]

In order to achieve the above object, a path route switching device according to a first aspect of the present invention comprises:
A path route switching device for data transmission having at least two bidirectional paths consisting of a transmission path and a reception path, comprising: alarm detection means for detecting a path alarm from a transmission signal; and instructing path route switching from the transmission signal. Bit signal detection means for detecting a bit signal to be transmitted, a path alarm detected by the alarm detection means, or path switch means for switching a path route in accordance with the bit signal detected by the bit signal detection means; And a bit signal insertion unit that inserts a bit signal for instructing the switching of the path route into a transmission signal transmitted to the opposing node upon detection of

According to the present invention, the alarm detecting means includes:
For example, a path alarm is detected from the STM-N signal. The bit signal detecting means, for example, outputs a bit signal (RD) instructing to switch the path route from the STM-N signal.
I bit, etc.). The path switching means switches a path route according to a path alarm detected by the alarm detection means or a bit signal (RDI bit or the like) detected by the bit signal detection means. The bit signal insertion means includes:
When the alarm detection means detects a path alarm, it inserts a bit signal (RDI bit or the like) for instructing path route switching into a transmission signal transmitted to the opposite node. As a result, bidirectional switching of the path route can be appropriately performed.

In order to achieve the above object, a path route switching device according to a second aspect of the present invention is a path route switching device having at least two bidirectional paths including a transmission path and a reception path.
A path route switching device for DH transmission, comprising an STM
An alarm detection means for detecting a path alarm from the -N signal; an RDI bit detection means for detecting an RDI bit for instructing remote switching of the path route from the STM-N signal; Switching signal generation means for adding a detection signal generated when the RDI bit is detected by the RDI bit detection means to generate a switching signal for instructing path route switching; Path switching means for switching the path route according to the switching signal generated by the means, and when the alarm detection means detects a path alarm, an RDI bit for instructing remote switching of the path route is added to the transmission signal transmitted to the opposite node. RDI bit inserting means for inserting. That.

According to the present invention, the alarm detecting means includes:
A path alarm is detected from the STM-N signal. RDI
The bit detecting means detects an RDI bit instructing remote switching of a path route from the STM-N signal.
The switching signal generating means adds a detection signal generated when the alarm detecting means detects the path alarm and a detection signal generated when the RDI bit detecting means detects the RDI bit, and instructs to switch the path route. Generate a switching signal. The path switch switches the path route according to the switching signal generated by the switching signal generator. The RDI bit insertion unit inserts an RDI bit for instructing remote switching of a path route into a transmission signal transmitted to the opposite node when the alarm detection unit detects a path alarm. As a result, bidirectional switching of the path route can be appropriately performed.

In order to achieve the above object, a path protection method according to a third aspect of the present invention is a path protection method in data transmission having at least two bidirectional paths including a transmission path and a reception path. An alarm detection step of detecting a path alarm from the transmission signal, a bit signal detection step of detecting a bit signal instructing to switch the path route from the transmission signal, and the path alarm detected in the alarm detection step or A path switch step for switching a path route according to the bit signal detected in the bit signal detection step, and when a path alarm is detected in the alarm detection step, a bit signal for instructing path path switching is transmitted to the opposite node. Bit signal to be inserted into the transmitted signal Characterized in that it comprises an insertion step.

According to the present invention, the alarm detecting step detects, for example, a path alarm from the STM-N signal. The bit signal detecting step includes, for example, STM-N
A bit signal (such as an RDI bit) for instructing switching of a path route is detected from the signal. The path switch step switches the path route according to the path alarm detected in the alarm detection step or the bit signal detected in the bit signal detection step. In the bit signal insertion step, when a path alarm is detected in the alarm detection step, a bit signal for instructing switching of a path route is inserted into a transmission signal transmitted to the opposite node. As a result, bidirectional switching of the path route can be appropriately performed.

In order to achieve the above object, a path protection method according to a fourth aspect of the present invention is a path protection method in SDH transmission having at least two bidirectional paths including a transmission path and a reception path. An alarm detection step of detecting a path alarm from the STM-N signal, an RDI bit detection step of detecting an RDI bit instructing a remote switching of a path route from the STM-N signal, and a path alarm in the alarm detection step. Is detected, or the RD
In the state where the RDI bit is detected in the I signal detection step, a switching signal generation step of generating a switching signal for instructing the switching of the path route, and a path route is generated according to the switching signal generated in the switching signal generation step. A path switch step for switching, and when a path alarm is detected in the alarm detecting step, an RDI bit for instructing remote switching of a path route is set.
Inserting an RDI bit into a transmission signal transmitted to the opposing node.

According to the present invention, the alarm detecting step detects a pass alarm from the STM-N signal.
The RDI bit detection step detects an RDI bit instructing remote switching of a path route from the STM-N signal. The switching signal generation step includes a state in which a path alarm is detected in the alarm detection step, or an RDI
In a state where the RDI bit is detected in the signal detecting step, a switching signal for instructing the switching of the path route is generated. The path switching step switches the path route according to the switching signal generated in the switching signal generating step. The RDI bit insertion step includes, when a path alarm is detected in the alarm detection step, an RDI bit for instructing remote switching of a path route,
It is inserted into the transmission signal transmitted to the opposite node. As a result, bidirectional switching of the path route can be appropriately performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A path route switching device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an example of a path route switching device applied to the embodiment of the present invention.
This path route switching device is, for example, an SDH (Synchronous
ousDigital Hierarchy) Used for transmission. As shown in the figure, in the path route switching device, opposing nodes 1 and 2 are connected via a path 3 and a path 4 which are transmission routes of two routes. Here, the path 3 is composed of a bidirectional path of the reception path 3a and the transmission path 3b with respect to the node 1, and the path 4 is a bidirectional path of the reception path 4a and the transmission path 4b with respect to the node 1. Consists of a path. An STM-N (synchronous transfer module level N (N = 1, 4, 64)) signal is transmitted to each path.

The node 1 includes a path switch unit 11, path alarm detection units 12a and 12b, and an RDI detection unit 13.
a, 13b, adders 14a, 14b, and RDI inserters 15a, 15b.

The path switch 11 switches the path route to one of the reception path 3a and the reception path 4a in accordance with a switching signal supplied from the addition section 14a or 14b. Specifically, when the switching signal is supplied from the adding unit 14a, the path switch 11 changes the path route to the reception path 3a.
When the switching signal is supplied from the adding unit 14b, the path route is switched to the reception path 4a.

The path alarm detection unit 12a receives the reception path 4
A path alarm is detected from among the STM-N signals received via a. This path alarm occurs, for example, when a failure such as a disconnection occurs in the path 4a. Path alarm detector 1
2a, upon detecting the path alarm, adds a detection signal indicating the detection of the path alarm from the STM-N signal to the adder 14;
a, and also supplies a detection signal to the RDI insertion unit 15a. Similarly, the path alarm detection unit 12b
Detects a path alarm from the STM-N signal received via the reception path 3a, and adds the detection signal to the adder 14b.
To the RDI insertion unit 15b.

The RDI (Remote Defect Indication) detector 13a receives the STM-N received via the reception path 4a.
The RDI bit (high state) is detected from the signal. The RDI bit here is the RD of the opposing node 2 which will be described later.
This is bit information of the STM-N signal in which a bit is set (high state) and inserted by the I insertion unit 25b.
When detecting the RDI bit, the RDI detecting unit 13a
A detection signal indicating the detection of the RDI bit from the TM-N signal is supplied to the adder 14a. Similarly, the RDI detection unit 13b transmits the STM-N received via the reception path 3a.
When an RDI bit (bit information inserted by the RDI insertion unit 25a) is detected from the signal, the detection signal is added to the addition unit 1
4b.

The adder 14a includes the path alarm detector 12
a and the detection signals supplied from the RDI detection unit 13a are added to each other and supplied to the path switch unit 11 as a switching signal. That is, when a detection signal is supplied from one of the path alarm detection unit 12a and the RDI detection unit 13a, the addition unit 14a supplies the path switch 11 with a switching signal for instructing switching of a path route. Also,
Similarly, the addition unit 14b adds the detection signals supplied from the path alarm detection unit 12b and the RDI detection unit 13b, respectively, and supplies the result to the path switch unit 11 as a switching signal.

The RDI insertion unit 15a transmits the transmission path 4 according to the detection signal supplied from the path alarm detection unit 12a.
STM- with the RDI bit set to b (high state)
The N signal is inserted, and the node 2 is instructed to switch the path route via the transmission path 4b. That is, when the path alarm detection unit 12a detects a path alarm from the reception path 4a, the RDI insertion unit 15a sets the RDI bit to instruct the node 2 to switch the pulse route through the RDI detection unit 23b. That is, this RD
The I bit functions as a path remote alarm. Similarly, the RDI insertion unit 15b transmits the transmission path 3b according to the detection signal supplied from the path alarm detection unit 12b.
, An STM-N signal with the RDI bit set is inserted, and instructs the node 2 to switch the path route via the transmission path 3b.

On the other hand, the node 2
, Path alarm detectors 22a and 22b, RDI detectors 23a and 23b, adders 24a and 24b, RDI
It is configured to include the insertion portions 25a and 25b. Note that the configuration of the node 2 is the same as the configuration of the node 1, and different reference numerals are assigned for easy understanding of the description. That is, since each configuration of the node 2 has substantially the same function as each configuration of the node 1, the description thereof is omitted.

Hereinafter, the operation of the path route switching device according to the embodiment of the present invention will be described with reference to FIG.
FIG. 2 is a schematic diagram for explaining how the path route switching device detects the occurrence of a failure and simultaneously switches bidirectional path routes. Before the occurrence of the failure, the path switch unit 11 has selected the reception path 4a.
It is assumed that the path switch unit 21 has selected the transmission path 4b. That is, it is assumed that the node 1 performs data transmission via the WEST route and the node 2 performs data transmission via the EAST route.

First, when a failure such as disconnection occurs in the reception path 4a, the path alarm detection unit 12a of the node 1 detects a path alarm from the STM-N signal received via the reception path 4a. The path alarm detector 12 adds a detection signal indicating the detection of the path alarm to the adder 14a and the RDI.
Each is supplied to the insertion part 15a. Upon receiving the detection signal, the adding unit 14a supplies a switching signal for instructing the switching of the path route to the path switch unit 11. Then, the path switch unit 11 switches the path route from the reception path 4a to the reception path 3a according to the switching signal.

The RDI insertion unit 15a, which has also received the detection signal, sets the RDI bit on the transmission path 4b.
The MN signal is inserted, and the node 2 is instructed to switch the path route via the transmission path 4b.

On the other hand, the RDI detector 23b of the node 2
When the RDI bit (high state) is detected from the STM-N signal of the transmission path 4b, a detection signal indicating the detection of the RDI bit is supplied to the adder 24b. Upon receiving the detection signal, the adding unit 24b supplies a switching signal for instructing switching of the path route to the path switch unit 21. Then, the path switch unit 21 switches the path route from the transmission path 4b to the transmission path 3b according to the switching signal.

As a result, the path route switching device can appropriately perform bidirectional switching of the path route. That is, as shown in FIG. 2, when a failure occurs in the reception path 4a, the path route switching device not only switches the path route to the reception path 3b but also uses the RDI bit (path remote alarm) to transmit the transmission path 4b. Is also switched to the transmission path 3b. That is, a bidirectional path can be simultaneously switched to the same route. For this reason, when the failed path is maintained, confusion does not occur, and maintenance work by a maintenance worker or the like becomes easy.

At this time, data transmitted / received between the node 1 and the node 2 (path overhead K4 bytes, etc.)
Is not performed, overhead processing becomes unnecessary, and can be realized by making small-scale changes to the current path route switching device. For this reason, the bidirectional switching of the path route can be appropriately performed while reducing the development burden of hardware and software (firmware).

In the above embodiment, the description has been given of the path route switching device in the SDH transmission. However, in addition, a SONET (Synchronous Optical Network) which is a US standard
The same can be applied to.

[0032]

As described above, according to the present invention,
By making small-scale changes to the existing path route switching device, bidirectional switching of the path route can be appropriately performed while reducing the development burden of hardware and software (firmware).

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a configuration of a path route switching device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a switching operation of the path route switching device according to the embodiment of the present invention.

[Description of Signs] 1, 2 nodes 11, 21 Path switch sections 12a, 12b, 22a, 22b Path alarm detection sections 13a, 13b, 23a, 23b RDI detection sections 14a, 14b, 24a, 24b Addition sections 15a, 15b, 25a , 25b RDI insertion unit 3a, 4a Reception path 3b, 4b Transmission path

Claims (4)

[Claims] 1. A path route switching device for data transmission having at least two bidirectional paths consisting of a transmission path and a reception path, comprising: alarm detection means for detecting a path alarm from a transmission signal; Bit signal detection means for detecting a bit signal instructing switching of the path route, a path alarm detected by the alarm detection means, or according to the bit signal detected by the bit signal detection means,
Path switching means for switching a path route, and bit signal insertion means for inserting a bit signal for instructing path route switching into a transmission signal transmitted to the opposite node when the alarm detection means detects a path alarm. A path route switching device, characterized in that: 2. An SDH (Synchronous Diode) having at least two bidirectional paths consisting of a transmission path and a reception path.
and a path route switching device in the transmission of a digital transmission signal, wherein an STM-N signal (synchronous transmission module level N (N =
1, 4, 64)) an alarm detection means for detecting a path alarm from among the STM-N signals; an RDI bit detection means for detecting an RDI (Remote Defect Indication) bit for instructing remote switching of a path route from the STM-N signal; A switch for adding a detection signal generated when the detecting means detects a path alarm and a detection signal generated when the RDI bit detecting means detects the RDI bit, and generating a switching signal for instructing a path route switching. A signal generation unit, a path switching unit that switches a path route according to the switching signal generated by the switching signal generation unit, and an RDI bit for instructing a remote switching of the path route when the alarm detection unit detects a path alarm. R to be inserted into the transmission signal transmitted to the opposite node
And a DI bit insertion unit. 3. A path protection method in data transmission having at least two bidirectional paths consisting of a transmission path and a reception path, comprising: an alarm detection step of detecting a path alarm from a transmission signal; A bit signal detection step of detecting a bit signal instructing switching of a path route, a path alarm detected in the alarm detection step, or a path switch step of switching a path route according to the bit signal detected in the bit signal detection step; When a path alarm is detected in the alarm detection step, a bit signal insertion step of inserting a bit signal for instructing switching of a path route into a transmission signal transmitted to the opposite node. Path protection method. 4. A path protection method in SDH transmission having at least two bidirectional paths comprising a transmission path and a reception path, comprising: an alarm detection step of detecting a path alarm from an STM-N signal; An RDI bit detection step of detecting an RDI bit instructing remote switching of a path route from the N signals; a state in which a path alarm is detected in the alarm detection step; or an RDI bit in the RDI signal detection step.
In a state where the bit is detected, a switching signal generating step of generating a switching signal for instructing switching of a path route, a path switching step of switching a path route according to the switching signal generated in the switching signal generating step, An RDI bit insertion step of inserting an RDI bit for instructing remote switching of a path route into a transmission signal transmitted to the opposite node when a path alarm is detected in the alarm detection step. Path protection method.