JP2001077783A - Transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize a reserve system optical transmission line when an active system is in normal condition without ruining a function as a redundant structure and sacrificing the redundant switching function. SOLUTION: When a switching factor occurs to a side of a main optical terminal station device 4-1 including a case in which a signal degrade(SD) faulty is detected or its own device faulty occurs on the side of the main optical terminal station device 4-1, a multiple section-remote defect indication(MS-RDI) is transferred to a transmitter 101 through an active system optical transmission line 2-1. In an active system device 101, a part time traffic output to a P/T optical transmission line 7-1 is shut down with detection of this MS-RDI as a trigger and the main optical terminal device 4-1 is made to detect a loss of signal(LOS). Next, the main optical terminal device 4-1 and the transmitter 101 are made to transfer a pass-alarm indication signal(P-AIS) to the side of the output of the part time traffic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, SDH (Syn
chronous Digital Hierarchy) or SONET (Sync
(Hronous Optical Network). In particular, ITU-T Recommendation G. 841 (in the case of SDH) A transmission device having a function of autonomously switching transmission paths using APS bytes specified by APS bytes and a function of accommodating part-time traffic with a part-time transmission line About.

[0002]

2. Description of the Related Art In recent years, there has been a demand for the development of a broadband ISDN based on a globally unified user network interface.
In response to this, a standard for uniformly multiplexing various high-speed services and existing low-speed services, that is, SDH / S
ONET has been standardized.

[0003] SDH / SONET is a high-speed transmission technology used in a backbone network of a telecommunications carrier, and requires high reliability. For this reason, transmission devices (including terminal devices) in the system and transmission paths connecting the transmission devices often adopt a redundant configuration in which a protection system (protection system) is provided for an active system (service system).

Since the protection system is provided as a backup for the service system, it does not fulfill its role when the service system is normal. Therefore, it is conceivable to effectively use the protection system transmission line when the service system transmission line is normal. For example, Japanese Patent Application No. Hei 7-215598 discloses this invention.
883).

The advantages of the invention described in the above publication will be briefly described with reference to FIG. FIG. 15 is a diagram in which FIG. 6 in the above publication is diverted as it is, and schematically shows a state in which both the active system device 10-0 and the active optical transmission line 6-0 are normal for one channel. is there.

The multiplexing terminal device shown in FIG. 15 has a duplex configuration including a working system device 10-0 and a protection system device 10-1. The working system device 10-0 has a working system optical transmission line. 6
−0 is connected to the standby system optical transmission line 6-1 in the standby system device 10-1.
Are connected respectively. Of these, the standby system 10-
1 includes a changeover switch 33 and a part-time traffic (P / T) optical transmission / reception module 32.
The P / T terminal 9 is connected to the T optical transmission / reception module 32 via the P / T optical transmission line 7 and the P / T optical terminal device 8.

In the above configuration, the changeover switch 33 is connected to the P / T optical transmission / reception module 32 at the time of normal operation. As a result, part-time traffic can be transmitted via the standby optical transmission line 6-1 and the standby optical transmission line 6-1 can be used effectively. When a failure occurs, the switch 33 is switched to the standby optical transmission / reception module 31 to allow service traffic to flow to the standby apparatus 10-1 via the standby optical transmission line 3.
Does not impair the function as a redundant configuration.

According to the invention described in the above publication, reliability is maintained without impairing the function as a duplex configuration,
When the working system is normal, the protection system optical transmission line can be used effectively.

By the way, SDH / SONET has various characteristic functions. Among them, when a failure occurs, control information is exchanged between transmission apparatuses to perform redundant switching autonomously and in a short time. There is a function.

This redundancy switching function is called APS (Automatic Protection Switching) in SDH, and the section overhead (SO
This is executed based on the control information described in the APS byte (also referred to as K byte) provided in H). AP
For details on the protocol of ITU-T Recommendation G.S. 8
41 (07/95).

[0011]

However, when it becomes necessary to execute APS due to a failure in the working system, the credibility of information transmitted and received via the working optical transmission line is lost. For this reason, the above-mentioned recommendation clearly specifies that the transmission and reception of the APS byte is performed via the standby optical transmission line.

However, in the multiplexing terminal device described in the above publication, there is a case where transmission and reception of the APS byte cannot be performed via the standby optical transmission line.

That is, it is assumed that a failure has occurred in the working optical transmission line 2 (to the left in the drawing) from the working system device 10-0 to the main optical terminal device 4 from the normal state shown in FIG. The main optical terminal device 4 which has detected the failure rewrites the APS byte and transfers the APS byte to the protection device 10-1 via the protection optical transmission line 3.

However, in the normal state, the standby system 1
Since the standby optical transmission / reception module 31 and the separation circuit 34a are separated at 0-1, the standby optical transmission line 3
Cannot be dropped by the separation circuit 34a. Therefore, despite the occurrence of a failure, APS bytes cannot be exchanged according to the recommendation, and as a result, there has been a problem that the redundancy switching cannot be executed.

The present invention has been made in view of the above circumstances,
Its purpose is to provide a transmission device that can effectively use the standby optical transmission line when the working system is normal without losing the function as a redundant configuration and without sacrificing the redundancy switching function. Is to do.

[0016]

In order to achieve the above object, the present invention takes the following measures. (1) An active device connected to an active transmission line related to transmission of main traffic, a standby transmission line, and a transmission line for sub traffic related to transmission of sub traffic different from the main traffic, such as part-time traffic. A redundant system is provided with a standby system device connected to the communication system, and a redundant switch is performed based on control information such as an APS byte, which is exchanged with another transmission device via the standby system transmission line. For example, in an SDH / SONET transmission apparatus provided with a redundancy switching function such as an APS function, the auxiliary traffic apparatus is selectively connected to the standby system transmission line or the auxiliary traffic transmission line. Is connected to the secondary traffic transmission line via the secondary traffic transmission path, If it is connected to the sending passage is,
At least fetching the control information transmitted from the opposite device via the standby transmission line, for example, RST /
MST (Regenerator Section Termination / Multiplex)
(Section Termination), etc., and when the signal processing means is connected to the sub-traffic transmission line and the own device side needs to perform redundancy switching, When the opposite device receives a notification that the redundant switching is required,
The signal processing unit is connected to the backup transmission line, and the signal processing unit exchanges the control information with the opposite device via the backup transmission line to execute the redundancy switching function. When the control information is exchanged between the connection control means to be provided and the signal processing means and the counterpart device, the P-AIS (P-AIS) Pass-A
and an erroneous connection prevention means for preventing the connection by transferring the signal to the downstream side.

(2) The connection control means is, for example,
The signal processing means is connected to the protection transmission line when the main traffic transmitted from the opposite device via the working transmission line is in an alarm state.

(3) Alternatively, the connection control means indicates that the control information transmitted from the opposing device via the working transmission line requires a redundant switch on the opposing device side. In this case, the signal processing means is connected to the protection transmission line.

(4) Further, according to the present invention, there is provided a transmission apparatus used in a transmission system including the transmission apparatus according to any one of the above (1) to (3), wherein the own apparatus needs to perform redundancy switching. In the case where a notification has occurred, a notifying means is provided for notifying the transmission device to the opposite end via the working transmission line.

(5) As an example, the notifying means sets the main traffic transmitted through the working transmission line in an alarm state, thereby notifying the self-device that the necessity of redundant switching has occurred. To the transmission device to be executed.

(6) Or the notifying means has the same information as the control information transmitted through the protection transmission line,
The control information such as the APS byte is also sent to the working transmission line, and the fact that the own device needs to perform redundancy switching is written in the control information sent to the standby and working transmission lines, whereby The opposite transmission device is notified that the device needs to be switched redundantly.

Therefore, according to the present invention, when the signal processing means is connected to the sub-traffic transmission line, that is, in a normal state, when it becomes necessary to switch the redundancy to the own device side, the connection control means controls the signal processing means. , Signal processing means are connected to the standby transmission line.

[0023] Thus, the signal processing means and the opposing device are connected via the backup transmission line, and it is possible to exchange control information such as APS bytes via the backup transmission line.

Therefore, in SDH, ITU-
T Recommendation G. The provision of 841 that “the APS byte transmitted and received via the backup transmission line is used at the time of APS” is satisfied, and the redundant switching can be performed.

Further, according to the present invention, when it becomes necessary for the opposing device to perform redundancy switching in a normal state, it is possible to receive a notification to that effect. With this as a trigger, the connection control unit can connect the signal processing unit and the opposing device via the backup transmission line, and can execute the redundant switching in the same manner as described above.

Further, according to the present invention, when the control information is exchanged between the signal processing means and the opposite device by the incorrect connection prevention means, the main traffic flows out to the transmission path of the sub traffic. Is prevented, thereby making it possible to avoid misconnection.

In the text, the term “transmission device” means not only a node device installed in a network but also a terminal device,
Multiplexing terminal equipment, cross-connect equipment, terminal equipment, etc.
It is a term applied to a broad concept including so-called NE (Network Element) in general.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, SD
H. (First Embodiment) FIG. 1 shows a configuration of an information transmission system according to the present embodiment. In this system, a plurality of transmission apparatuses 101 to 10m are connected in a chain in a series via an active optical transmission line 6-0 and a standby optical transmission line 6-n.
Each of the optical transmission lines 6-0 and 6-1 is, for example, an STM-16 (Sy
nchronous Transfer Module Level-16) High-speed multiplexed transmission line with class-class capacity.

Monitoring and control devices 111 to 11m are connected to the transmission devices 101 to 10m via a LAN (Local Area Network) 1, respectively. Monitoring and control device 111
11 to 11 m are realized, for example, as general-purpose workstations, and any of the monitoring control devices 111 to 11 m can perform monitoring control on each of the transmission devices 101 to 10 m. It is not necessary to make the number of the monitoring and control devices 111 to 11m correspond to the number of the transmission devices 101 to 10m on a one-to-one basis, and the number of installations may be determined according to the demand of the system.

Working system optical transmission line 6-0, standby system optical transmission line 6
The signal transmitted via -n is dropped via the low-speed line L to a not-shown switch, a dedicated line node, an ATM cross-connect device, or the like. The signal introduced into each transmission device via the low-speed line L is multiplexed into an SDH frame and transferred to another transmission device via the working optical transmission line 6-0 and the protection optical transmission line 6-n. Is done. Working optical transmission line 6
−0, SDH is applied to an interface related to signal transmission via the protection optical transmission line 6-n.

The transmission device 101 is connected to the main optical terminal units 4-1 to 4-1 connected to the main terminals 5-1 to 5-n, respectively.
4-n and P / T optical terminal equipment 8- connected to part-time traffic terminals (P / T terminals) 9-1 to 9-n.
1 to 8-n are connected.

The main optical terminal units 4-1 to 4-n are connected to the working optical transmission lines 2-1 to 2-n and the protection optical transmission lines 3 respectively.
It is connected to the transmission apparatus 101 via -1 to 3-n and is responsible for transmitting service traffic. That is, the transmission device 10
Each of the transmission lines connecting the optical network unit 1 and the main optical terminal units 4-1 to 4-n has a duplex configuration. On the other hand, each of the P / T optical terminal apparatuses 8-1 to 8-n has a single-configuration P / T optical transmission line 7.
It is connected to the transmission device 101 via -1 to 7-n and is responsible for transmission of part-time traffic. Part-time traffic is traffic having a relatively lower priority than service traffic, such as in-house data transmission and low-cost data transmission services.

As described above, the transmission device 101 accommodates n channels. FIG. 2 shows a configuration corresponding to one channel for service traffic and part time traffic.

FIG. 2 is a diagram showing a configuration of a portion corresponding to one channel for service traffic and part time traffic in FIG. That is, FIG.
Corresponds to a portion surrounded by a dotted line in FIG. In FIG. 2, the main optical terminal unit 4-1, the main terminal 5-1, the P / T optical terminal unit 8-
1. P / T terminal 9-1 is taken as an example, but the main optical terminal unit 4-
The same applies to 2 to 4-n, main terminals 5-2 to 5-n, P / T optical terminal devices 8-2 to 8-n, and P / T terminals 9-2 to 9-n.

In FIG. 2, the transmission apparatus 101 includes an active system apparatus 10-0 connected to the active optical transmission line 6-0, and a standby system apparatus 10-1 connected to the standby optical transmission path 6-1. It has. Active system device 10-0 and standby system device 10
The operation control for −1 is mainly performed by the main control unit 37 based on a program stored in the storage unit 36.

The main optical terminal unit 4-1 is connected to the working optical transmission line 2
Active low-speed interface unit (LSI
/ F) 38-0 and a backup low-speed interface (LS I / F) 38-1 that accommodates the backup optical transmission line 3-1. Active system device 10-0 and standby system device 10-
1, the service traffic transmitted from each of the active LS I / F 38-0 and the backup LS
The service traffic is taken in via the I / F 38-1, one of the service traffics is selected by the selector 39, and guided to the main terminal 5-1 via the channel switching unit 40 and the interface unit (I / F) 41.

On the other hand, the service traffic transmitted from the main terminal 5-1 passes through the interface unit 41 and the channel switching unit 40, and is branched into two, and the active LSI I / I
F38-0 and the standby LS I / F 38-1, and the active device 10-0 and the standby device 10-1 via the active optical transmission line 2-1 and the standby optical transmission line 3-1 respectively. Is transmitted to Active LS I / F38-0,
The operation control for the standby LS I / F 38-1, the selector 39, the channel switching unit 40, and the interface unit 41 is mainly performed by the control unit 43 based on the program stored in the storage unit 42.

SDH is also applied here to the interface relating to signal transmission in the working optical transmission line 2-1 and the protection optical transmission line 3-1 that connects the main optical terminal unit 4-1 and the transmission device 101. I do.

Further, the standby device 10- of the transmission device 101
1 is connected to the P / T optical terminal device 8-1 via the P / T optical transmission line 7-1. P via the P / T optical transmission line 7-1
The part-time traffic transmitted to the / T optical terminal apparatus 8-1 is transmitted to the low-speed interface (LS I / F) 4
4. Channel switching unit 45, interface unit (I / F)
It is provided to the P / T terminal 9-1 via 46. Also P /
The part-time traffic transmitted from the T terminal 9-1 is transmitted from the interface unit 46, the channel switching unit 45, and the low-speed interface unit 44 to the protection device 10-1 via the P / T optical transmission line 7-1. .

Here, the main control unit 37 of the transmission apparatus 101 is realized as, for example, a microcomputer or the like.
In addition to the known function objects involved in performing the S function,
Alarm switching means 3 as a functional block according to the present embodiment
7a and P-AIS transfer means 37b.

The alarm switching means 37a is connected to the active optical transmission line 2
-1 is monitored, and the changeover switch 33 shown in FIG.
a and 33b are switched. That is, in the normal state, the alarm switching unit 37a sets the RST / MSTs 34a and 34b to P
/ T optical transmission line 7-1. This enables transmission of part-time traffic.

On the other hand, when a switching request is issued from the normal state to the transmission apparatus 101 side, or when the main optical terminal apparatus 4-
If the traffic transmitted from 1 to 4-n via the working optical transmission line 2-1 is in an alarm state, the alarm switching unit 37a switches the RST / MSTs 34a and 34b to the standby optical transmission line 3-1. To the side. By doing so, the alarm switching unit 37a is able to control the A through the standby optical transmission line 3-1.
It enables transmission and reception of PS bytes.

As a case where a switching request is generated on the own device side, when switching is requested from the monitoring control devices 111 to 11m of FIG. 2, (FS: Forced Switch, MS: M
failure in the active optical transmission line 2-1 flowing into its own device (SF: Signal Fail, SD: Signal De
grade) is detected.

When the RST / MSTs 34a and 34b are connected to the standby optical transmission line 3-1 by the alarm switching unit 37a, the P-AIS transfer unit 37b switches the standby high-speed I / F unit 18 (FIG. 3). The traffic transmitted to the transmission apparatus 102 via the standby optical transmission line 6-1 is controlled by the P-AI
S (Pass-Alarm Indication Signal) is inserted to destroy information included in this traffic. In this way, the service traffic flowing from the standby LSI / F 38-1 (FIG. 3) to the own device (the transmission apparatus 101) via the standby optical transmission line 3-1 is transferred to the standby optical transmission line 6. -1
And prevents service traffic from being misconnected to the transmission path of part-time traffic.

The control unit 43 of the main optical terminal unit 4-1 is realized as, for example, a microcomputer or the like, and as a functional block according to the present embodiment, an alarm transfer unit 43a.
And P-AIS transfer means 43b.

The alarm transfer means 43a is connected to the main optical terminal unit 4-
In the case where a switching request occurs on the side 1, the active optical transmission line 2
By setting the traffic transmitted to the transmission apparatus 101 via -1 in an alarm state, the main optical terminal apparatus 4-1 is notified of the occurrence of the switching request to the transmission apparatus 101. The signal indicating the alarm state is MS-RDI
(Multiple Section-Remote Defect Indication) or MS-AIS (MultipleSection-Alarm Indication Sign)
al).

The P-AIS transfer means 43 b
01 by the alarm switching means 37a.
When the part time traffic from the P / T optical transmission line 7-1 is lost due to the connection of (FIG. 3) to the standby system optical transmission line 3-1 side, the RST / MST 52b is controlled to be downstream. The P-AIS is inserted into the P / T transmission path to the side.

Next, a more detailed configuration will be described with reference to FIG. FIG. 3 shows the active system device 10-0 and the standby system device 1.
0-1, active LS I / F 38-0, standby LS I / F
FIG. 40 is a block diagram showing a configuration of the / F38-1 and the LS I / F44. That is, FIG. 3 corresponds to a portion surrounded by a dotted line in FIG.

In FIG. 3, an active system device 10-0 includes an active system high-speed interface (I / F) unit 14, an active system demultiplexing unit 13, and changeover switches 12a, 12b, 23a,
23b and the receiving RST / MST (Regenerator Sectio
n Termination / Multiplex Section Termination) 22
a, the transmitting RST / MST 22b, and the receiving SPI
(SDH Physical Interface) 21a and transmitting side SPI2
1b.

The standby system device 10-1 includes a standby high-speed interface (I / F) unit 18 and a standby system demultiplexing unit 1
7 and changeover switches 16a, 16b, 35a, 35b,
33a, 33b, a receiving-side RST / MST 34a, a transmitting-side RST / MST 34b, and a receiving-side SPI 31a and a transmitting-side SPI 31b for the standby optical transmission line 3-1, respectively.
SPI3 for the P / T optical transmission line 7-1
2a and a transmission-side SPI 32b.

The active high-speed I / F unit 14 interfaces with the active optical transmission line 6-0. The working-system demultiplexing unit 13 multiplexes the service traffic given from the receiving RST / MST 22a or 34a for n channels and provides the working traffic to the working high-speed I / F unit 14. The working-system multiplexing / demultiplexing unit 13 separates the service traffic given from the working-system high-speed I / F unit 14 into n channels, and separates the separated traffic into a transmission side RS corresponding to each channel.
Lead to T / MST 22b or 34b.

The receiving RST / MSTs 22a and 34a are:
Frame synchronization processing, descrambling processing, signal monitoring, MSOH (Mu
ltiple Section Over Head). The APS byte drop processing is executed in the receiving RST / MSTs 22a and 34a.

The transmitting RST / MSTs 22b and 34b
It performs frame synchronization processing, scramble processing, signal monitoring, MSOH transmission processing, and the like for the given SDH frames. Rewriting and insertion of APS bytes are performed in the transmitting RST / MSTs 22b and 34b.

The receiving-side SPIs 21a, 31a, 32a and the transmitting-side SPIs 21b, 31b, 32b perform an optical / electrical conversion process, a code conversion process, and the like on a transmission signal.

Changeover switches 12a, 35a, 23a, 1
6a switches the route of the received service traffic between the active system and the standby system. Changeover switches 12b, 35
The switches b, 23b, and 16b switch the service traffic to be transmitted between the active system and the standby system. The switches 33a and 33b switch between service traffic and part-time traffic in the standby system device 10-1.

The active LS I / F 38-0 is connected to the transmitting side S
PI 47a, receiving side SPI 47b, receiving side RST / MS
T48a and a transmitting RST / MST 48b. The standby LS I / F 38-1 is connected to the transmitting side SPI 49
a, Receiving SPI 49b, Receiving RST / MST 50
a, a transmitting-side RST / MST 50b.

Of these, the transmitting side RST / MST 48b,
The output signals from 50b are both supplied to the changeover switch 39, and any one of the output signals is selectively supplied to the channel switching unit 40 according to the active / standby switching state.
Further, the service traffic transmitted from the channel switching unit 40 is branched into two, and the receiving-side RST / MST 48a,
50a are provided together.

The LS I / F 44 is connected to the transmitting side SPI 51
a, Receiving SPI 51b, Receiving RST / MST 52
a, a transmitting RST / MST 52b.

Next, the operation of the present embodiment will be described with reference to FIGS. First, in a normal state where there is no failure in the network, service traffic and part-time traffic are transmitted along the route shown in FIG. In other words, the service traffic indicated by the solid line in the figure is transmitted between the active system device 10-0 and the active LS I / F 38-.
0 is transmitted in both directions. The part-time traffic indicated by the dashed line in the figure is transmitted bidirectionally between the standby system device 10-1 and the LS I / F 44.

In this state, the main optical terminal unit 4-1 monitors the occurrence of the switching factor in steps S1 to S3 as shown in the flowchart of FIG. Similarly, the transmission apparatus 101 performs steps S11 to S13.
Monitors the occurrence of the switching factor.

In this state, when the main optical terminal unit 4-1 is requested to switch from any of the monitoring and control devices (Yes in step S1), or when the active optical transmission line 2-1 performs the switching operation.
When the main optical terminal unit 4-1 detects a transmission line alarm that satisfies the F (Signal Fail) condition (Yes in step S2), the main optical terminal unit 4-1 proceeds to step S4, and the active system The MS is transmitted to the transmission apparatus 101 via the optical transmission path 2-1.
-Forward RDI alert. The operation in step S4 is based on ITU-T Recommendation G. 841.

On the other hand, when the main optical terminal unit 4-1 detects a transmission line alarm that satisfies the SD (Signal Degrade) condition in the working optical transmission line 2-1 or when the main optical terminal device 4-1 has its own working optical transmission line 2-.
When a fault relating to one system is detected (Y in step S3)
In es), the main optical terminal device 4-1 proceeds to step S5, and forcibly inserts the MS-RDI alarm into the signal transmitted to the transmission device 101 via the working optical transmission line 2-1. I do.

That is, the transmission apparatus 101 does not normally meet the conditions for transmitting the MS-RDI.
The MS-RDI is transferred via the working optical transmission line 2-1 to the MS-RDI.

In response to this, the transmission apparatus 101 detects MS-RDI from the main optical terminal unit 4-1 in step S14. FIG. 6 schematically shows the operation so far. That is, the switching factor generated in the main optical terminal unit 4-1 is notified to the transmission apparatus 101 by MS-RDI transmitted via the working optical transmission line 2-1.

Now, the transmission apparatus 1 which has detected the MS-RDI
01 moves to step S15, and controls the changeover switch 33b as shown in FIG. 7 to shut down part-time traffic to the P / T optical transmission line 7-1.

In response to this, the main optical terminal unit 4-1 detects the LOS (Loss Of Signal) of the part-time traffic (step S6), and the transmitting-side RST / MST 52b.
In P, the part-time traffic transmission route to the low-speed side
-Transfer the AIS (step S7). This destroys the traffic and prevents the service traffic from being misconnected to the part-time traffic passage during the redundancy switching.

Similarly, the transmission apparatus 101 also executes step S16.
8, the P-AIS is transferred by the standby high-speed I / F unit 18 to the part-time traffic passing route to the high-speed side as shown in FIG.

After preventing misconnection of the part-time traffic in both directions in this way, the main optical terminal unit 4-1 transmits the APS byte including the switching request to the transmitting RST / MST 50a in step S8 of FIG. And transmits it to the transmission apparatus 101 via the standby optical transmission path 3-1.

After step S16, the transmission apparatus 101 sets the changeover switch 33a to SPI3 as shown in FIG.
Switch to the 1a side, and drop the APS byte transmitted via the standby optical transmission line 3-1 at the receiving RST / MST 34a (step S17). Thus, the transmission of the APS byte from the main optical terminal device 4-1 to the transmission device 101 via the protection optical transmission line 3-1 is completed.

Subsequently, as shown in FIG. 10, the transmission apparatus 101 switches the changeover switch 33b to the SPI 31b side, inserts the APS byte into the backup traffic at the transmitting RST / MST 34b, and transmits the APS byte via the backup optical transmission line 3-1. To the main optical terminal unit 4-1 (step S1).
8). In response to this, the main optical terminal unit 4-1 transmits the APS byte transmitted via the protection optical transmission line 3-1 to the receiving side RPS.
Drop at ST / MST 50b (Step S
9). As a result, the transmission device 101 transmits the main optical terminal device 4
APS through the standby optical transmission line 3-1
The transmission of the byte is completed.

Through the above steps, APS bytes are bidirectionally transmitted and received between the transmission apparatus 101 and the main optical terminal unit 4-1 via the protection system optical transmission line 3-1. The transmission device 101 interprets the contents of the APS byte sent from the main optical terminal device 4-1 and, as shown in FIG.
a and the changeover switch 35a, and the changeover switch 12b and the changeover switch 35b, respectively, to connect the service traffic to the protection optical transmission line 3-1 and the protection device 10-1.
Detour to. Similarly, the main optical terminal device 4-1 is the transmission device 1
Interpretation of the APS byte from No. 01, the selector 39 is connected to the standby LS I / F 38-1 and the standby optical transmission line 3
-1 is introduced into the device. Thus, the redundant switching based on the APS is completed (Step S10 in FIG. 5).

As described above, in the present embodiment, the switching to the main optical terminal unit 4-1 is performed including the case where the SD failure is detected on the main optical terminal unit 4-1 side or the own device failure occurs. If a factor occurs, the working optical transmission line 2-1
The MS-RDI is transferred to the transmission apparatus 101 via the. The active device 101 shuts down the output of the part-time traffic to the P / T optical transmission line 7-1 with the detection of the MS-RDI as a trigger, and sends the L to the main optical terminal device 4-1.
The OS is detected. Next, the main optical terminal device 4-1 and the transmission device 101 transfer the P-AIS to the output side of the part-time traffic.

With this configuration, the transmission device 10 that cannot drop the APS byte of the protection optical transmission line 3-1 because it accommodates part-time traffic in a normal state.
1 can be notified to the opposing device that a switching factor has occurred. In response to this, the transmission apparatus 101 separates the part-time traffic and starts monitoring the protection optical transmission line 3-1. Therefore, transmission and reception of APS bytes via the standby optical transmission line 3-1 can be realized, and both accommodation of part-time traffic and redundancy switching function by APS can be achieved. That is, when the working system is normal, the backup optical transmission line can be effectively used, and a transmission device that does not impair the redundancy switching function can be provided.

Further, since the P-AIS is forwarded to the output side of the part-time traffic prior to the switching of the redundancy, it is possible to prevent the service traffic from being misconnected to the path through which the part-time traffic passes.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 12 shows a configuration of the transmission apparatus 101 and the main optical terminal 4-1 according to the present embodiment.
That is, in the present embodiment, the functional blocks provided in the main control unit 37 and the control unit 43 are different from those in the first embodiment.

In the present embodiment, the main control section 37 of the transmission apparatus 101 includes an APS byte switching section 37c instead of the alarm switching section 37a. APS byte switching means 3
7c monitors the APS byte in the SDH frame of the service traffic transmitted via the working optical transmission line 2-1, and switches the changeover switches 33a and 33b in FIG. 3 according to the monitoring result. That is, in the normal state, the APS byte switching means 37c sets the RST / MST 34
a and 34b (FIG. 3) are connected to the P / T optical transmission line 7-1 to enable transmission of part-time traffic.

On the other hand, when a switching request is issued from the normal state to the transmission apparatus 101 side, or when the main optical terminal apparatus 4-
If the content indicated by the APS byte transmitted from the first through 4-n via the working optical transmission line 2-1 is other than [No Request: no switching request], the APS byte switching means 3
7c connects the RST / MSTs 34a and 34b to the standby optical transmission line 3-1. By doing so, the APS byte switching means 37c enables transmission and reception of APS bytes via the standby optical transmission line 3-1.

On the other hand, the main controller 43 of the main optical terminal unit 4-1
Has an APS byte notifying unit 43c in place of the alarm transferring unit 43a. The APS byte notification means 43c
When a switching request occurs on the main optical terminal unit 4-1 side,
The APS byte rewritten by the APS function is used not only for the standby optical transmission line 3-1 but also for the working optical transmission line 2-1.
Is also sent. That is, the standby optical transmission line 3-
1. The same information is described in the APS byte in the traffic transmitted through the working optical transmission line 2-1.

Therefore, when a switching request occurs on the main optical terminal unit 4-1 side, the APS byte in which information different from the above [No Request] is written is used for the working optical transmission line 2-1. Is transmitted to the transmission apparatus 101 via the.

Next, the operation of the above configuration will be described with reference to FIGS. First, under normal conditions, service traffic and part-time traffic are
3 is transmitted. FIG. 13 is the same as FIG. 4 except that the main optical terminal unit 4-1 has the RST / MST4
8A, the APS byte is inserted into the service traffic to the transmission apparatus 101 side, and the transmission apparatus 101 drops the APS byte of the service traffic in the RST / MST 22a. That is, even in the steady state, APS bytes are exchanged at least on the working transmission line 2-1 in the direction of the main optical terminal unit 4-1 to the transmission device 101.

In this state, the main optical terminal unit 4-1 operates as shown in FIG.
As shown in the flowchart, the occurrence of a switching factor is monitored in steps S19 to S22. Similarly, the transmission apparatus 101 monitors the occurrence of the switching factor in steps S28 to S30.

From this state, if any of steps S19 to S22 becomes Yes, that is, if a switching factor occurs on the main optical terminal unit 4-1 side, the main optical terminal unit 4-1 becomes the switching factor. The corresponding APS byte is rewritten (step S23). Next, the main optical terminal device 4
-1 inserts this APS byte into the service traffic transmitted to the transmission apparatus 101 via the working optical transmission path 2-1 and the protection optical transmission path 7-1 (step S24).

On the other hand, the transmission apparatus 101 determines in step S28
If any of Steps S30 to S30 becomes Yes, that is, if a switching factor occurs on the transmission apparatus 101 side, the process proceeds to Step S32.

The transmission apparatus 101 is connected to the working optical transmission line 2.
As a result of monitoring the APS byte transmitted via −1, if information other than [No Request] is described, specifically, the content of the upper 4 bits (bridge request code) of the K1 byte is “0000”. "If it is unexpected, the process proceeds to step S32.

Then, the transmission apparatus 101 proceeds to step S3
2 controls the changeover switch 33b so that the P / T optical transmission path 7
Shut down part-time traffic to -1. Hereinafter, the same procedure as in the first embodiment is performed (steps S25 to S27, and step S33).
To step S35), the redundant switching based on the APS is completed (step S36 in FIG. 14).

As described above, in the present embodiment, APS bytes having the same contents are transmitted to the protection optical transmission line 3-1 and the working optical transmission line 2-1. In other words, the same APS byte is para-fed to the standby optical transmission line 3-1 and the working optical transmission line 2-1. When a switching factor occurs on the main optical terminal unit 4-1 side, the active optical transmission line 2-1 is used.
When the contents other than [No Request] are described in the APS byte transmitted via, the transmission device 101 is notified that a switching factor has occurred on the main optical terminal device 4-1 side. .

Since the above operation is performed, the main optical terminal unit 4-1
It is possible to notify the transmission apparatus 101 of the occurrence of the switching factor to the transmission side and release the part-time traffic to trigger the APS function. That is, similarly to the first embodiment, it is possible to provide a transmission device that can effectively use the protection optical transmission line when the working system is normal and does not impair the redundancy switching function. Becomes

Further, according to the present embodiment, it is possible to notify the occurrence of the switching factor without forcibly setting the service traffic to the alarm state. Thereby, ITU-T Recommendation G. The object of the present invention can be achieved while observing the alarm transfer condition of 841.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the description has been made with SDH in mind, but the idea of the present invention can be applied to SONET standardized in the United States. In each of the above embodiments, the network shape (network topology) is on a so-called chain. However, the present invention is not limited to this. For example, the present invention can be applied to a ring-shaped network.

In the first embodiment, the MS-RD
Although the service traffic is set in the alert state by transferring I, the MS-AIS may be used instead. In short, the traffic transmitted via the working optical transmission line 2-1 may be forcibly set to the alarm state.

In each of the above embodiments, the information contained in the traffic is destroyed by the P-AIS in order to prevent the misconnection. However, the same effect can be obtained by transferring the unequipped signal.

In each of the above embodiments, the transmission device 101
Has been described in relation to the main optical terminal equipment 4-1. However, the same applies to the relations with the other main optical terminal equipments 4-2 to 4-n. 10
The same applies to the relationship between adjacent transmission devices, such as 2.

In addition, various modifications can be made without departing from the scope of the present specification.

[0094]

As described above in detail, according to the present invention, when the working system is normal, the spare system optical transmission is performed without impairing the function as a redundant configuration and without sacrificing the function of switching redundancy. The road can be used effectively.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of a portion corresponding to one channel for service traffic and part-time traffic in FIG.

FIG. 3 shows an active system device 10-0 and a standby system device 10 shown in FIG.
-1, active LSI / F38-0, standby LSI I / F
38-1 is a block diagram showing a configuration of an LS I / F 44.

FIG. 4 is a diagram showing transmission routes of service traffic and part-time traffic in a normal state.

FIG. 5 is a flowchart showing an operation procedure of the main optical terminal device 4-1 and the transmission device 101 according to the first embodiment of the present invention.

FIG. 6 is a diagram schematically showing a state at the time when an SD alarm or a device failure alarm occurs from the steady state in FIG. 4 to the main optical terminal device 4-1 side.

FIG. 7 is a diagram schematically showing a state at the time when the transmission device 101 performs shutdown of part-time traffic, following the state of FIG. 6;

FIG. 8 is a diagram schematically showing a state in which the P-AIS is transferred to the output side of the standby optical transmission line on the transmission apparatus 101 side, following the state of FIG. 7;

FIG. 9 is a diagram schematically showing a state in which the APS byte from the main optical terminal unit 4-1 is dropped by the transmission apparatus 101, following the state of FIG.

FIG. 10 is a diagram schematically showing a state in which APS bytes transmitted between the main optical terminal device 4-1 and the transmission device 101 are dropped following the state of FIG. 9;

FIG. 11 is a diagram schematically showing a state in which redundancy switching has been completed after transmission and reception of APS bytes.

FIG. 12 is a diagram showing a configuration of a transmission apparatus 101 and a main optical terminal 4-1 according to the embodiment.

FIG. 13 is a diagram schematically showing transmission and reception of APS bytes via the active optical transmission line 2-1 in a steady state in the second embodiment of the present invention.

FIG. 14 is a flowchart illustrating an operation procedure of the main optical terminal device 4-1 and the transmission device 101 according to the second embodiment of the present invention.

FIG. 15: Japanese Patent Application No. 7-215598 (Japanese Unexamined Patent Application Publication No.
In the multiplexing terminal device described in JP-A-64883, a diagram schematically showing a state in which both the active system device 10-0 and the active optical transmission line 6-0 are normal for one channel.

[Explanation of symbols]

101 to 10 m Transmission device 111 to 11 m Monitoring and control device 1 LAN (Local Area Network) 2-1 to 2-n Working optical transmission line 3-1 to 3-n Protection optical transmission line 4-1 4-n ... main optical terminal equipment 5-1-5-n ... main terminal 6-0 ... working optical transmission line 6-1 ... standby optical transmission line 7-1-7-n ... part-time traffic ( P / T)
Optical transmission line 8-1-1 to 8-n P / T optical terminal equipment 9-1 to 9-n P / T terminal L ... Low-speed line 10-0 ... Working system device 10-1 ... Spare system device 12a, 12b, 23a, 23b switch 13 working multiplexing / demultiplexing unit 14 working high speed interface (I / F) unit 21a receiving SPI (SDH Physical Interface) 21b transmitting SPI 22a receiving RST / MST ( Regenerator Section
Termination / Multiplex Section Termination) 22b: RST / MST on the transmitting side 16a, 16b, 33a, 33b, 35a, 35b: Switch 31a, 32a: SPI on the receiving side 31b, 32b: SPI 34a on the transmitting side: RST / MST 34b on the receiving side: transmitting Side RST / MST 36 Storage unit 37 Main control unit 37a Alarm switching unit 37b P-AIS transfer unit 37c APS byte switching unit 38-0 Active low-speed interface unit (LS I /
F) 38-1... Standby low-speed interface unit (LS I /
F) 39 selector 40 channel switching unit 41 interface unit (I / F) 42 storage unit 43 control unit 43a alarm transfer unit 43b P-AIS transfer unit 43c APS byte notification unit 44 low-speed interface unit (LS I / F) 45 channel switching unit 46 interface unit (I / F) 47a, 49a, 51a transmitting SPI 47b, 49b, 51b receiving SPI 48a, 50a, 52a transmitting RST / MST 48b , 50b, 52b ... RST / MST on the receiving side

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 11/20 C F term (Reference) 5K002 AA05 BA06 DA01 EA33 FA01 5K014 AA01 AA05 CA04 CA06 EA07 FA01 FA09 HA01 5K028 AA14 KK01 KK03 KK35 MM05 5K030 GA12 HA10 HC15 JA12 JL03 JL10 LA15 LA17 LC09 LE06 MB01 MD02 9A001 CC02 LL09

Claims (6)

[Claims] 1. An active device connected to an active transmission line related to transmission of main traffic, and a protection device connected to a protection transmission line and a sub traffic transmission line related to transmission of sub traffic different from the main traffic. A transmission device having a redundancy switching function of performing a redundancy switching based on control information exchanged with another transmission device via the backup transmission line. The device is selectively connected to the backup transmission line or the sub-traffic transmission line, and when connected to the sub-traffic transmission line, transmits the sub-traffic via the sub-traffic transmission line. In connection with this, when connected to the backup transmission line, the control information transmitted from the opposite device via the backup transmission line is less likely to be fetched. The signal processing means is connected to the sub-traffic transmission line, and when the own apparatus needs to perform redundancy switching, or when the opposing apparatus switches to the opposing apparatus, When receiving a notification that the need for redundant switching has occurred, the signal processing unit is connected to the backup transmission line, and the signal processing unit is connected to the opposite device via the backup transmission line. Connection control means for exchanging the control information and providing the execution of the redundancy switching function; and when the control information is exchanged between the signal processing means and the opposing device, the main traffic is A transmission device comprising: an erroneous connection preventing unit that prevents a sub traffic from flowing out to a transmission path. 2. The connection control unit connects the signal processing unit to the backup transmission line when main traffic transmitted from the opposite device via the active transmission line enters an alarm state. The transmission device according to claim 1, wherein: 3. The connection control means according to claim 1, wherein said control information transmitted from said opposing device via said active transmission line indicates that the opposing device needs to perform redundant switching. 2. The transmission apparatus according to claim 1, wherein the signal processing unit is connected to the protection transmission line. 4. A transmission apparatus for use in a transmission system including the transmission apparatus according to claim 1, wherein when a self-device side needs to perform redundancy switching, the transmission device opposes the fact. A transmission device, comprising: a notification unit that notifies a device via the working transmission path. 5. The notifying means sets a main traffic transmitted through the working transmission line in an alarm state, thereby notifying the opposing transmission apparatus that redundancy switching is required on its own side. The transmission apparatus according to claim 4, wherein the transmission is performed. 6. The notifying means sends control information having the same information as control information transmitted via the protection system transmission line to the working system transmission line, and it is necessary to switch redundancy to its own device side. By writing the fact that this has occurred in the control information transmitted to the standby and working transmission lines, the self-device side is notified to the opposite transmission device that the need for redundancy switching has occurred. The transmission device according to claim 4, wherein