JP2003134072A - Transmission line switching error avoidance method and transmission line switching error avoidance system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a system for evading transmission line switching abnormality by which safe package replacing work with shortened time can be performed. SOLUTION: These method and system are constituted of: a first step for comparing received APS byte from an opposite device with a faulty state of the present device and with APS byte which is attempted to be transmitted after recognizing recovery from a fault when an SDH interface signal storage package provided to a transmitter is replaced; and a second step for suppressing APS byte transmission for fixed time so that no abnormal cut back is produced according to comparison.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line switching abnormality avoidance method and a transmission line switching abnormality avoidance system, and particularly, in a transmission line switching control system, they are opposed to each other via a redundant transmission line constituted by an active system and a standby system. The present invention relates to a bidirectional transmission path switching abnormality avoiding method and a transmission path switching abnormality avoiding system which are performed by transmitting and receiving switching control information between transmitting and receiving apparatuses using section overheads (SOH) of both systems. More specifically, when the interface (IF) board included in the transmission device fails or is removed, the device becomes a device failure of the interface board and the opposite device becomes a transmission path failure, but both devices detect the failure. of,
It relates to the APS byte sequence between the devices at the time of restoration.

[0002]

2. Description of the Related Art As a conventional system of this type, there is one described in JP-A-7-226729. According to the present invention, the system switching control information APS byte is inserted into the SOH of the main signal corresponding to SDH in the system APS byte transmitting unit on the transmission side, and the system failure information transmitting unit includes the K2 byte of the APS byte. Fault information indicating the presence / absence of a fault in each system is inserted in the lower 3 bits of. Here, SDH is Synchronous Digital
Abbreviation for Hierarchy, and refers to the international standard for high-speed relay speed system compiled by ITU-T. Also, A
What is PS? Automatic Protection
Abbreviation of Switch, SOH is Section Ove
Abbreviation for r Head.

On the other hand, on the receiving side, failure information is extracted by the failure information receiving section of the receiving section of each system, and the presence or absence of a failure is determined. Then, the selector is switched according to the switching control information of the APS byte of the system having no failure.

FIG. 11 is a diagram showing a conventional fault detection / fault recovery recognition sequence. This figure shows a sequence in which a failure is detected in both the own device and the opposite device, and thereafter recovery is recognized. As the APS byte, K1 / K2 bytes of SOH on the transmission path are used. In this figure, A
The station device and the B station device face each other, and K when switching
Transmission / reception of 1 / K2 bytes is shown in time series.

Now, the package (PK of the own station device (station A))
G) Since a failure has occurred (x in the figure), replace the PKG. Then, Sig from the local device A to the opposite device B
A nalFailure (hereinafter abbreviated as SF) switching request (C110) is transmitted (S1). Here, the symbol "C1
"10" is a symbol indicating a protocol predetermined in the transmission system (the same applies hereinafter). The opposite device B receives the switching request SF. Then, the transmission path is switched (S2), which means a response. Reverse Request
st (hereinafter abbreviated as RR) 2110 is transmitted (S3).
The own station device A receives the RR transmitted from the opposite device B and switches the transmission path (S4).

After that, in the opposite device B, the P
KG failure and transmission path failure due to removal are recognized (S5),
Although it becomes an SF switching trigger, since the switching operation has already been performed by the own station device A becoming the master station, the SF transmission of the opposite device B is suppressed.

After that, since the SF of the own station device A is recovered (S6), the recovery standby protection time is started, and Wait t
o Restoration (hereinafter abbreviated as WTR) 6110 is transmitted (S7). Upon receiving the WTR, the opposite device B recognizes the failure recovery of the opposite device (own device A) (S8), and transmits the suppressed SF switching request C110 (S9). By this operation, the opposite device B becomes the master station. Upon receiving the SF (C110), the own station device A changes from the master station to the slave station (S9).

[0008] The own station device A receives the RR from the opposite device B.
(2110) is transmitted (S10). After that, when the opposite device B receives the RR signal and recognizes the recovery of the transmission line failure (S11), it sends the WTR (6110) to the own device A.
Is transmitted (S12). Then, the recovery standby protection starts. Then, after the protection time has elapsed, No Request (hereinafter abbreviated as NR) 0020 is transmitted (S13), and the name change operation is performed. Here, the name change operation is a name change operation of the active system and the standby system. NR (0020) is transmitted from the local device A to the opposite device B (S1).
4).

The above-mentioned sequence is generally performed in Japan and will be referred to as a first switching system.

[0010]

In the above-mentioned first switching method, when the package is exchanged, the following sequence occurs, the transmission line is switched, and the signal is interrupted. It was This is called switching back due to an abnormal RR sequence. FIG. 12 to FIG. 14 are explanatory diagrams of the occurrence of switching back. FIG. 12 shows a case where the SF recovery at the local device A is faster than the package insertion detection at the remote device B when the opposite device B exchanges the package, and FIG. If the package insertion detection in A is slower than the SF recovery in the opposite device B,
FIG. 14 shows a case in which the package insertion detection in the opposing device B is faster than the SF recovery in the local device A when the opposing device B replaces the package.

Here, the sequence shown in FIG. 12 will be described in detail. When the 0-system package is removed by the opposing device B, the local device A detects the SF, which is the transmission line failure, and the opposing device B is requested to switch to the 1-system.
0 is transmitted by K1 / K2 bytes (procedure 1). When the opposite device B receives the SF switching request for 1-system, 1
Switch the transmission path to the system (procedure 2)
A switching response (hereinafter abbreviated as RR) 2110 is transmitted in response to K1 / K2 bytes (procedure 3). When the local station A receives the RR, the transmission path is switched to the 1-system (procedure 4), and the transmission path switching by the 0-system package removal is completed.

After that, when the 0-system package is inserted in the opposite device B, the SF recovery is first detected in the own device A,
It will be in the recovery standby state. Therefore, the recovery standby 6110
(WTR) is transmitted by K1 / K2 bytes (procedure 5). When the opposite device B receives the WTR in the standby state for recovery,
Since the opposite device B is still in the 0-system package failure state, the SF switching request C110 for the 1-system SF is transmitted to the local device A by K1 / K2 bytes (procedure 6).

When the own station device A receives the SF switching request, the SF switching request from the opposite device B has a higher priority than the recovery standby state which is the current switching state. RR (2110) to K1 / K2
Send in bytes (procedure 7). On the other hand, the opposite device B recognizes the recovery from the package failure before receiving the RR from the local device A, and determines the RR for the switching request in the standby for recovery transmitted by the local device A. Send to A (procedure 8).

At this point, both the local station device A and the remote station device B are in the state of transmitting RR (2110), and there is no master station, so both stations switch back (SWB).
K) occurs (procedure 9). The occurrence of such switching back is the same in the sequence shown in FIG. 13 and the sequence shown in FIG.

The present invention has been made in view of the above problems, and provides a transmission path switching abnormality avoiding method and a transmission path switching abnormality avoiding system capable of performing a safe package exchanging operation with a short exchange time. It is intended to be provided.

[0016]

(1) FIG. 1 is a flow chart showing the principle of the method of the present invention. According to the first aspect of the present invention, when the SDH interface signal accommodating package included in the transmission device is replaced, the APS byte received from the opposite device after the failure recovery is recognized and the failure state of the own device and the APS byte to be transmitted are compared. Depending on the step and the comparison result, to prevent abnormal switching back,
And a second step of suppressing APS byte transmission for a certain period of time.

When the package operated by the above-mentioned first switching system fails, or when the function of the package is upgraded, the package is replaced. Until now, after removing the package to be replaced, before the new package is inserted, the maintenance person locks out (Lo
ck Out) is performed to fix the current switching state, and then a maintenance worker needs to perform a preparatory work before the package replacement, such as inserting the package.

For this reason, preparation work and confirmation work are required at the time of package replacement, and when the preparation / confirmation work is not performed due to careless mistake of the maintenance person, when abnormal RR processing occurs at the time of package insertion. In that case, the transmission path switches to the side where the package is inserted,
There was a problem that the main signal was cut off momentarily.

According to the present invention, when the package is inserted, the switching process (task) is stopped until the expected K1 / K2 bytes are received from the opposite device so as not to fall into the abnormal RR process, thereby preparing for the package replacement. It becomes possible to carry out the package exchange work which eliminates the work and is safe and shortens the exchange time.

(2) In the invention according to claim 2, after recognition of the failure recovery, the APS byte received from the opposite apparatus is compared with the failure state of the own apparatus and the APS byte to be transmitted, and the result is compared. It is characterized in that the processing relating to that interface is skipped for a certain period of time, and the switching function relating to other interfaces is made operable.

According to the first aspect of the invention, since the switching process (task) is stopped, the switching process (task) is stopped for a long time depending on the recovery confirmation protection time of the opposite device, and the switching operation in other protection is performed during that time. There is a problem that you can not do. Therefore, according to the present invention, when it is determined that the abnormal RR process falls into the package insertion, the abnormal RR process is avoided without stopping the switching process (task), and the switching operation by another protection is performed even while the abnormal RR process is being avoided. Is possible.

(3) According to the third aspect of the present invention, the switching control information is transmitted between the transmission devices opposed to each other via the redundant transmission line constituted by the active system and the standby system by the SOH of the transmission lines of both systems.
In the system for transmitting / receiving at the time, when the SDH interface signal accommodating package included in the transmission device is exchanged, the APS byte received from the opposite device after the faulty line is recognized, the fault state of the self device, and the APS to be transmitted.
Depending on the means for comparing the bite and the comparison result of the comparing means, a certain time A
Means for suppressing PS byte transmission.

According to this structure, when the package is replaced, the abnormal RR process is prevented from occurring, so that the maintenance work by the maintenance person can be eliminated and the package replacement work can be performed with a shorter replacement time. Is possible.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram showing a system configuration example for implementing the method of the present invention. In the figure, 10 is hardware. Reference numeral 1 denotes an SF / SD change detection processing unit, which is SF or SD (S
It is called when (Initial Degrade) occurs / recovers, and when the failure is recovered, an abnormal RR is issued if necessary.
Call the avoidance timer control processing unit 6 or receive K1 /
The received K1 / K2 bytes are read from the K2 byte read processing unit 2 and the current SF / SD failure information and the received K1 / K2 bytes are read.
The switching control main processing unit 3 is notified of byte information.

Reference numeral 2 denotes a reception K1 / K2 byte read processing unit, which reads the reception K1 / K2 bytes currently received for the designated line from the hardware 10 according to a request from each processing unit, and reads the result. To the request source.

Reference numeral 3 denotes a switching control main processing section, which is the switching control information (SF / SD, K1 / K) passed from each processing section.
2. The current switching state is determined based on the unit state information), and the bridge (Bridge) / switch (Switchc) is determined.
The transmission path switching control of h) and the transmission K1 / K2 byte setting are executed for the hardware 10. Where B
Ridge is to send the same signal to the 0/1 system,
Switch means 0/1 system switching.

Reference numeral 4 denotes a received K1 / K2 byte change detection processing unit, which calls the abnormal RR avoidance timer control processing unit 6 as necessary when the received K1 / K2 byte changes.
Alternatively, the changed received K1 / K2 byte information is notified to the switching control main processing unit 3.

A package state change processing unit 5 notifies the switching control main processing unit 3 together with the current package state when the package state changes (from normal to abnormal or from abnormal to normal).

Reference numeral 6 denotes an abnormal RR avoidance timer control processing unit, which is the SF / SD change detection processing unit 1 or the reception K1 / K2.
The bite change detection processing unit 4 is activated when it is determined that the abnormal RR processing falls into the abnormal RR processing, and the abnormality RR avoidance processing unit 7 is activated after a predetermined time.

Reference numeral 7 denotes an abnormal RR avoidance processing unit, which is an abnormal RR.
The avoidance timer control processing unit 6 is activated after a certain time, the latest reception K1 / K2 bytes are read by the reception K1 / K2 bytes reading processing unit 2, and the reception K1 / K2 bytes information is notified to the switching control main processing unit 3. .

The components 1 to 7 described above can be realized by either hardware or software. The outline of the operation of the system configured as above will be described below.

When the SF / SD change detection processing unit 1 detects the recovery of the transmission line failure, the current switching operation state becomes an abnormal RR state, or the received K1 / K2 byte change detection processing unit 4 When a change in the received K1 / K2 bytes is detected at, an error occurs in the current switching operation status RR
If it is in a state, switching processing (task) for a certain period of time
Then, after restarting, the received K1 / K2 byte read processing unit 2 reads the received K1 / K2 byte and notifies the switching control main processing unit 3.

When the SF / SD change detection processing unit 1 or the received K1 / K2 byte change detection processing unit 4 is in an abnormal RR state, the abnormal RR avoidance timer control processing unit 6 is requested to perform timer control. Then, after the time-out, the abnormal RR avoidance processing unit 7 is activated, the received K1 / K2 byte is read from the received K1 / K2 byte read processing unit 2, and the switching control main processing unit 3 is notified.

3 to 5 are diagrams showing an operation sequence example of the present invention. FIG. 3 is a first operation sequence, FIG. 4 is a second operation sequence of the present invention, and FIG. 5 is a third operation sequence of the present invention. Is an operation sequence of. Hereinafter, these sequences will be described. (In the case of FIG. 3 and FIG. 4) In FIG. 3, the SF is recovered by the SF / SD change detection processing unit 1 of the own station device A after the package is inserted in the package exchange work in the opposite device B. Recognize what you have done. Then, the SF / SD change detection processing unit 1 notifies the switching control main processing unit 3 that the SF has been recovered (hereinafter referred to as failure recovery). In Figure 4,
The package state change processing unit 5 recognizes that the package has been inserted in the package exchange work in the local device A, and the package state change processing unit 5 notifies the switching control main processing unit 3 that the package is normal (hereinafter , Failure recovery).

When the switching control main processing unit 3 is notified of the failure recovery, the switching state becomes the recovery standby state. After that, the K1 / K2 byte of the SF switching request is transmitted from the opposite apparatus B, and the receiving K1 / K2 byte change detection processing unit 4 recognizes it in the local apparatus A. Receive K1 / K2
The byte change detection processing unit 4 judges that the K1 / K2 byte received from the opposite device B is an SF switching request, and the state of the local station device A is in a standby state for recovery, so that an abnormal RR state occurs, To wait for RR reception from the opposite device B,
Stop the switching process (task).

Further, in the opposite apparatus B, in order to recognize the failure recovery while the switching processing (task) of the own station apparatus A is stopped, the K1 / K2 bytes of the recovery standby transmitted from the own station apparatus A. In response, K1 / K2 bytes of RR are transmitted. In the own station device A, when the switching process (task) is restarted, the reception K1 / K2 byte read processing unit 2 again.
Read the received K1 / K2 bytes through the counter device B
By recognizing the RR reception from the device, it is possible to prevent an abnormal RR state. (In the case of FIG. 5) Reception of the receiving device K1 of the local device A after the package is inserted in the package exchange work in the opposite device B.
/ K2 Byte change detection processing unit 4 K1 / K for recovery standby
The switching control main processing unit 3 is notified that 2 bytes have been received.

The switching control main processing unit 3 waits for recovery K1.
/ K2 byte reception is notified, SF detection is currently being performed, and since SF detection has a higher priority than K1 / K2 byte reception in recovery standby, the K1 / K2 byte of the SF switching request is sent to the opposite device B. Send. After that, when it is recognized that the SF has recovered, similar to the SF / SD change detection processing unit 1, S
In the F / SD change detection processing unit 1, since the K1 / K2 byte received from the opposite device B is not RR and the state of the own station is the SF switching request, it is determined that an abnormal RR state occurs, The switching process (task) is stopped to wait for the RR reception from the opposite device B.

Further, in the opposite apparatus B, while the switching processing (task) of the own station apparatus A is stopped, in order to recognize the SF switching request transmitted from the own station apparatus A, the RR corresponding thereto is transmitted. . When the switching process (task) is restarted in the own station device A, the received K1 / K2 byte read processing unit 2 again reads the received K1 / K2 byte, and the RR from the opposite device B is received, thereby causing an abnormal RR.
Prevent falling into a state.

As a result, when the package is replaced, the package can be replaced without fixing the current switching operation state and then performing the preparatory work before the package replacement such as inserting the package.

In the cases of FIG. 3 and FIG. 4, the switching state of the local station device A is in the recovery standby state, and then the reception K1 /
When the K1 / K2 byte received from the opposite device B in the K2 byte change detection processing unit 4 is the SF switching request, it is determined that an abnormal RR occurs and the RR reception is waited for for the RR reception from the opposite device B. The abnormal RR avoidance timer control processing unit 6 is notified together with the time designation until waiting. The abnormal RR avoidance timer control processing unit 6 starts measurement for the requested time, and after the requested time, the abnormal RR avoidance processing unit 7
To notify.

In the abnormal RR avoidance processing unit 7, the reception K is received again.
By reading the received K1 / K2 bytes through the 1 / K2 byte read processing unit 2 and recognizing the RR reception from the opposite device B, the abnormal RR state is prevented.

Further, when the abnormal RR avoidance timer control processing unit 6 is operating, there is a possibility that the switching state changes shown in FIGS. 6 to 10 may occur. There is. 6 is an operation sequence when SF is generated in the local station A during timer operation, FIG. 7 is an operation sequence when the SF is recovered in the local station A during timer operation, and is recovered, and FIG. 8 is a timer operation 9 shows an operation sequence in the case where SD occurs in the local station A during operation, FIG. 9 shows an operation sequence in which SD recovers after the occurrence in the local station A during timer operation, and FIG. 10 shows the local station during timer operation A
Is an operation sequence when SF is received after once receiving RR.

Referring to FIG. If the received SF cannot be recognized at the time of recovery of the own station active system SF, the S
It is impossible to respond to F. Therefore, in order to prevent this, when the SF is received at the time-out point and the state is waiting for the SF recovery, the received APS (SF) is reflected and the state transition is performed.

The sequence is omitted until the self station is recovered. Upon recognizing the SF recovery, the local apparatus A transmits the WTR (6110) to the opposite apparatus B (S1). On the side of the opposite device B, when this WTR is received, since SF response is being made until then, SF (C110) is sent to the device A side of the own device.
Is transmitted (S2). Here, the timer is started on the side of the local station device A. When the active station SF is detected on the side of the own station device A during this timer activation, the own station device A transmits the SF (C110) to the opposite device B (S3). At this point, both the own station device A and the opposite device B are in the SF recovery waiting state.

The opposite device B sends SF to the own device A.
(C110) is transmitted (S4), and the local apparatus A transmits SF (C110) to the opposite apparatus B (S10).
5). Here, when the timer times out, the own station device A reflects the SF reception, and both stations wait for the SF recovery. Here, when the SF recovery is detected in the local apparatus A, the RR (2110) is transmitted from the local apparatus A to the opposite apparatus B (S6).

Next, FIG. 7 will be described. If the receiving SF cannot be recognized when the local working SF WTR times out, the opposite device B cannot respond to the SF. Therefore, in order to prevent this, the SF is received at the time out and the SF WTR is being transmitted. When it is, the received APS (SF) is reflected and the state transition is performed.

Next, FIG. 8 will be described. In the change during the occurrence of SD, after the SD is generated in the own station device A, the opposite device B is notified by the SF, but the own station device A continues the SD. In order to prevent this, if the SF is received at the time of timeout and the SD recovery waits, the receiving APS (S
The state transition is performed by reflecting F).

Next, FIG. 9 will be described. In the case of recovery after the occurrence of SD, in the change during the occurrence of SD, after the occurrence of SD in the own station device A, the opposite device B is notified by SF,
SD of the local device A continues (SD
Continued during WTR transmission). To prevent this, SF reception
When the SD WTR is being transmitted, the received APS (SF) is reflected and the state transition is performed.

Next, FIG. 10 will be described. Although the received APS has changed by the time-out, it is necessary to avoid the abnormal RR again. Therefore, the timer is further activated to extend the timer.

Next, the operation of FIGS. 3 to 5 will be described in detail. First, the operation sequence of FIG. 3 will be described. This figure shows a case where the 0-system transmission path (active system) is used and the 0-system package of the opposite device B is replaced. When the opposite apparatus B removes the 0-system package to be replaced, the local apparatus A recognizes that the 0-system transmission path has become SF, and notifies the opposite apparatus B of the 1-system transmission path (spare system). ) Is sent by K1 / K2 bytes (S1).

Upon receiving the SF switching request, the opposite device B executes switching to the 1-system transmission path (S2), and then transmits RR to the local device A in K1 / K2 bytes (S3). Upon receiving the RR, the local station device A switches the 1-system transmission path (S4).

When the opposite device B inserts a new package into the 0-system, the self-device A recognizes that the SF of the 0-system transmission path has recovered (procedure 1). In the local device A, SF
Is recovered, and there is no request from the remote device B to switch by K1 / K2 bytes. Therefore, the status change is performed during recovery standby protection, and the remote device B is notified that it is in recovery standby by K1 / K2 bytes. Send (procedure 2).

When the opposite device B receives the K1 / K2 bytes in the standby state for recovery from the own device A, since it recognizes that the 0-system package is in an abnormal state, the own device A
Request for SF switching to the 1-system transmission path to K1 / K2
Send in bytes (procedure 3). Upon receiving the K1 / K2 byte of the SF switching request for the system 1 from the opposite device B, the own device A is in the standby state for the switching state of its own device, and thereafter, the K1 / K2 bytes of the RR are set to the opposite device. B
It is determined that the abnormal RR will occur when it is sent to the device, and the switching process (task) is performed to wait for the RR reception from the opposite device B.
Stop (Process 1).

The opposite apparatus B recognizes that the 0-system package has been inserted while the switching processing (task) is stopped in the own station apparatus A (S5), and is in the standby state for recovery from the own station apparatus A. Since it continues to receive K1 / K2 bytes of
The RR is transmitted to the local device A by K1 / K2 bytes (procedure 4). When the switching process (task) is restarted, the own station device A reads the received K1 / K2 bytes again, recognizes the RR from the opposite device B, and enters the recovery standby protection state in which the own station device A is the master station. (Procedure 5).

Next, the sequence shown in FIG. 4 will be described. In the example of this figure, the case where the 0-system transmission path (active system) is used and the 0-system package of the local station device A is replaced is shown. When the 0-system package to be exchanged is removed by the local device A, the local device A recognizes that the 0-system package is removed (S1), and the 1-system transmission line (spare An SF switching request to the system) is transmitted by K1 / K2 bytes (S2).

Upon receiving the SF switching request, the opposite apparatus B executes the switching to the 1-system transmission path (S3), and then transmits the RR to the own station apparatus A in K1 / K2 bytes (S4). The local station device A that has received the RR executes switching of the 1-system transmission path (S5). When a new package is inserted in the 0-system in the own-station device A, it is recognized that the 0-system package is inserted in the own-station device A (procedure 1).

In the local device A, the package is inserted,
Further, since the switching request is not received from the opposite device B by K1 / K2 bytes, the switching state changes to the standby for recovery, and it is indicated that the opposite device B is in the recovery standby by K1 / K2.
Transmit with K2 bytes (procedure 2). In the opposite device,
When receiving K1 / K2 bytes waiting for recovery from the local device A, since it recognizes that the 0-system transmission line is still in the SF state, it sends the local system A to the 1-system transmission line. SF
The switching request is transmitted by K1 / K2 bytes (procedure 3).

When receiving the K1 / K2 bytes of the SF switching request from the opposite apparatus B to the 1-system, the local station apparatus A transmits the K1 / K2 bytes of the RR for the SF switching request to the opposite apparatus B after this. It is determined that an abnormal RR state occurs, and the switching process (task) is stopped to wait for RR reception from the opposite device B (process 1).

In the opposite apparatus B, while the switching processing (task) is stopped in the local apparatus A, the SF recovery of the 0-system transmission line is recognized and K1 / waiting for recovery from the local apparatus A.
Since it continues to receive K2 bytes, it transmits RR to its own station device A by K1 / K2 bytes (procedure 4).
When the switching process (task) is restarted, the own device A reads the received K1 / K2 bytes again, and the opposite device B
Recognizing the RR from the master station, the local station apparatus A is set as the master station and the recovery standby protection state is set (step 5).

As described above, according to this embodiment,
When the local device A receives the K1 / K2 byte of the SF switching request from the remote device B while the local device A is in the standby state for recovery, the remote device B
Recognizes that the package has been inserted, and in that case, the switching process (task) is stopped in the local device A, the switching process (task) is restarted after a certain time, and the reception K1 / from the opposite device B is again performed. By reading K2 bytes, it is possible to prevent the abnormal RR state from occurring when the package is inserted. As a result, the preparatory work when replacing the package is eliminated,
It is possible to perform the package exchange work which is safe and shortens the exchange time.

Next, the sequence shown in FIG. 5 will be described. This embodiment shows a case where the 0-system transmission path (active system) is used and the 0-system package of the opposite device B is replaced. When the opposite apparatus B removes the 0-system package to be replaced, the opposite apparatus B recognizes that the 0-system package has been removed (S1) and sets 1 for the own station apparatus A.
A request to switch SF to the system transmission line (standby system) is issued by K1 / K2.
It is transmitted in bytes (S2).

Upon receiving the SF switching request from the opposite apparatus B, the own station apparatus A executes switching to the 1-system transmission path (S3), and then transmits RR in K1 / K2 bytes (S).
4). Upon receiving the RR, the opposite device B executes switching to the 1-system transmission path (S5). When a new package is inserted into the 0-system in the opposing device B, it is recognized that the 0-system package is inserted in the opposing device B (procedure 1). In the opposite device B, since the switching request is not received from the local device A by the K1 / K2 byte, the switching state changes to the standby for recovery, and it is indicated that the local device A is in the standby for recovery by K1 / K2. Send by byte (procedure 2).

When receiving the K1 / K2 bytes in the standby state for recovery from the opposite device B, the own station device A recognizes that it is in the SF state of the 0-system transmission line, and therefore, sends 1 to the opposite device B. An SF switching request to the system transmission path is transmitted by K1 / K2 bytes (procedure 3). After that, the self-station A recognizes the SF recovery of the 0-system transmission line, but since the K1 / K2 bytes received from the opposite device B are on standby for recovery, after that, the K1 / K2 bytes of RR are transferred to the opposite device B. It is judged that it will fall into an abnormal RR state when it is sent to
Wait for R reception. Therefore, the switching process (task) is stopped (process 1).

In the opposite device B, while the switching processing (task) is stopped in the own device A, the
The K1 / K2 byte of the system SF switching request is received, and the RR is transmitted to the local station device A by the K1 / K2 byte (procedure 4). In the local device A, switching processing (task)
Restarts, read the received K1 / K2 bytes again,
The RR from the opposite device B is recognized, and the recovery protection state is set with the local device A as the master station (procedure 5).

According to this embodiment, when the own station apparatus A detects the SF recovery of the active system while receiving the reception K1 / K2 bytes of the recovery standby from the opposite apparatus B, the own station apparatus A The switching process (task) is stopped at A, the switching process (task) is restarted after a certain time, and the received K1 / K2 bytes from the opposite device B are read again, thereby preventing an abnormal RR state at the time of package insertion. be able to.

Next, another embodiment of the present invention will be described. When the local apparatus A receives the K1 / K2 byte of the SF switching request for the 1st system from the opposite apparatus B while the switching state is in the standby state for recovery, the K of the RR is then returned.
When 1 / K2 is transmitted to the opposite device B, it is determined that the abnormal RR state is set. Further, when the self-station device A recognizes the insertion of the package while the K1 / K2 bytes received from the opposite device B are waiting for recovery, the self-station device A thereafter sends the K1 / K2 bytes of RR to the opposite device B. It is determined that the abnormal RR state will occur if the data is transmitted to the terminal.

At this time, in order to wait for RR reception from the opposite device B, the time until waiting for RR reception is specified, and an abnormal RR is specified.
The avoidance timer control processing unit 6 (see FIG. 2) is notified. The abnormal RR avoidance timer control processing unit 6 starts measurement for the requested time, and notifies the abnormal RR avoidance processing unit 7 after the requested time. In the abnormal RR avoidance processing unit 7, the reception K1 / K2 byte read processing unit 2 again receives the reception K.
By reading 1 / K2 bytes, R from the opposite device B
R can be received, and a recovery standby protection state is set with the local station device A as the master station.

According to this embodiment, as a means for avoiding the abnormal RR at the time of package insertion, when it is determined that the local device A falls into the abnormal RR state, the timer control is activated, and after a predetermined time. Reception from the opposite device B again K1
By reading / K2 bytes, it is possible to prevent falling into an abnormal RR state when a package is inserted, and avoid movement RR regardless of how long the recovery confirmation protection time of the opposite device B is, without affecting the switching operation of other protection. Becomes

[0069]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first aspect of the present invention, when the package is inserted, the switching process (task) is stopped until the expected K1 / K2 bytes are received from the opposite device so that the abnormal RR process does not occur. Therefore, it is possible to eliminate the preparatory work at the time of package exchange and to perform the package exchange work that is safe and shortens the exchange time.

(2) According to the second aspect of the invention, when it is determined that abnormal RR processing will occur during package insertion, the abnormal RR processing is avoided without stopping the switching processing (task), and the abnormal RR processing is avoided. Even in the inside, switching operation with other protection is possible.

(3) According to the third aspect of the present invention, the abnormal RR process is prevented from occurring during the package replacement, thereby eliminating maintenance work for the package replacement by a maintenance person and shortening the replacement time. It becomes possible to perform package replacement work.

As described above, according to the present invention, it is an object of the present invention to provide a transmission line switching abnormality avoiding method and a transmission line switching abnormality avoiding system which are capable of performing a safe package exchanging work with a short exchange time. .

[Brief description of drawings]

FIG. 1 is a flow chart showing the principle of the method of the present invention.

FIG. 2 is a block diagram showing a system configuration example for implementing the method of the present invention.

FIG. 3 is a diagram showing a first operation sequence example of the present invention.

FIG. 4 is a diagram showing a second operation sequence example of the present invention.

FIG. 5 is a diagram showing a third operation sequence example of the present invention.

FIG. 6 is an operation sequence diagram when SF occurs in the local station device A during the timer operation.

FIG. 7 is an operation sequence diagram in the case where SF is generated in the local station device A during timer operation and then recovered.

FIG. 8 is an operation sequence diagram when an SD occurs in the local station device A during the timer operation.

FIG. 9 is an operation sequence diagram in the case where the local station device A recovers after SD occurs during the timer operation.

FIG. 10 is an operation sequence diagram in the case where SF is received after receiving RR once in the local station device A during the timer operation.

FIG. 11 is a diagram showing a conventional fault detection / fault recovery recognition sequence.

FIG. 12 is a first explanatory diagram of occurrence of switching back.

FIG. 13 is a second explanatory diagram of occurrence of switching back.

FIG. 14 is a third explanatory diagram of occurrence of switching back.

[Explanation of symbols]

1 SF / SD change detection processing unit 2 Receive K1 / K2 byte read processing unit 3 Switching control main processing unit 4 Receive K1 / K2 byte change detection processing unit 5 Package status change processing unit 6 Abnormal RR avoidance timer control processor 7 Abnormal RR avoidance processing unit 10 hardware

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuichi Namioka             2-3-9 Shin-Yokohama, Kohoku-ku, Yokohama-shi, Kanagawa             Issue Fujitsu Digital Technology Stock Association             In-house F term (reference) 5K014 AA01 CA06 FA01 HA10                 5K028 AA14 CC02 KK01 KK03 KK12                       MM05 PP04 QQ01 RR04

Claims (3)

[Claims] 1. When exchanging an SDH interface signal accommodating package included in a transmission device, comparing the received APS byte from the opposite device with the fault condition of the self device and the APS byte to be transmitted after the fault recovery is recognized. A transmission path switching abnormality avoiding method comprising the step 1 and a second step of suppressing APS byte transmission for a certain period of time so that abnormal switching does not occur depending on the comparison result. 2. After the failure recovery is recognized, the received APS byte from the opposite apparatus is compared with the failure status of the own apparatus and the APS byte to be transmitted, and the processing relating to the interface is skipped for a certain period according to the comparison result. 2. The transmission path switching abnormality avoidance method according to claim 1, wherein a switching function relating to another interface is made operable. 3. A system in which a switching device transmits / receives switching control information between transmission devices facing each other via a redundant transmission line composed of an active system and a standby system by means of SOH on both transmission lines Upon replacement of the SDH interface signal accommodating package, means for comparing the received APS byte from the opposite apparatus with the failure status of the self apparatus and the APS byte to be transmitted after the failure recovery is recognized, and the means for comparing the comparison result of the comparing means. And a means for suppressing APS byte transmission for a certain period of time so as not to cause abnormal switching back, a transmission line switching abnormality avoidance system.