JPH10154972A - Uninterruptible switching system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the uninterruptible switching system by avoiding undesired switching of a transmission line within an uninterruptible switching block so as to improve the transmission quality and the maintenance performance even on the occurrence of a switching operation with respect to a transmitter side input at the outside of the uninterruptible switching block. SOLUTION: A transmitter side inserts prescribed phase information to a signal received by phase information addition sections 3, 4 and provides outputs of two signals while being shared to active/standby transmission lines, phase adjustment sections 5, 6 receive the two signals of the active/standby systems of the transmitter side inputs and adjust a phase difference between the transmitter side input systems based on phase information included in the signals and provide an output of the result to selection sections 7, 8 provided to the active/ standby systems of the transmission lines. The selection sections 7, 8 select either of the two system signals of the transmitter side inputs received from the phase adjustment sections 5, 6 and provide an output of the selected signal to a transmission line. Since the selection sections 7, 8 receive the signal subject to phase adjustment, occurrence of an undesired error at the receiver side based on the switching of the selection sections 7, 8 is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-instantaneous interruption switching system for switching an active / standby system of a transmission line having a working / standby redundant configuration without instantaneous interruption. The present invention relates to a non-instantaneous-interruption switching method capable of automatically switching without any instantaneous interruption and no failure even when the switching is performed.

[0002]

2. Description of the Related Art Conventionally, this kind of non-stop switching method inserts a predetermined frame pattern on a transmitting side, which is a signal input terminal, and uses the frame pattern inserted on a transmitting side on a receiving side. By adjusting the phase difference between the working system and the standby system, the signal is temporarily stored in the memory at the output terminal on the receiving side, and the bit error of the signal input to this memory is monitored. When an error is detected, the error is included from the memory. It has a non-instantaneous interruption switching section for switching the transmission path between the working system and the protection system before the signal is output.

FIG. 3 is a connection diagram showing an example of a functional block in the instantaneous interruption switching section.

[0004] As shown in FIG. 3, on the transmitting side, signals of two working / stand-by systems are input to IFs (interface units) 1 and 2 from outside the non-interruptible switching section. Phase information for delay time adjustment for realizing instantaneous interruption switching is added to the input signal by each of the phase information adding units 3 and 4.

As the phase information to be added, a frame pattern having a period sufficiently longer than the transmission delay time difference between the working system and the protection system in the instantaneous interruption switching section is inserted by using an unused bit portion in the data signal. Is done. The signals to which the phase information has been added are output from the selectors 7 and 8 to the phase information adders 3 and 4.
And the selectors 7 and 8 each select one of the outputs of the phase information adding units 3 and 4, and one output signal of the selected phase information adding units 3 and 4 is used as an I / O signal for the working system.
The data is transmitted to the transmission path by the selectors 7 and 8 via F9 and F9, respectively.

[0006] The selection units 7 and 8 are units for executing redundant system switching of the transmission line at the stage preceding the instantaneous interruption switching section, and both are controlled so as to always select the same system. With this configuration, a signal to which the same phase information is always added in the non-interruptible switching section is transmitted to both the working system and the standby system. In the example of FIG. Are transmitted to both the working system and the protection system of the transmission path.

On the receiving side, each of the IFs 11 and 12 receives a signal from each of the working system and the protection system on the transmission path and outputs the signal to the phase adjusting units 13 and 14. The phase adjusters 13 and 14 use the phase information inserted on the transmission side to align the signal phases of the working system and the protection system. The signals having the same phase are monitored for errors by the error monitoring units 15 and 16 and are temporarily written to the memory units 17 and 18.

When an error is detected by the error monitoring units 15 and 16, the switching of the selection units 19 and 20 is performed before an erroneous signal is read from the memory units 17 and 18, thereby realizing instantaneous interruption switching. You.

[0009]

In the conventional hitless interruption switching system described above, the switching operation for the transmission-side input outside the hitless interruption switching section also causes the working system to switch from the working system to the protection system on the transmission line in the hitless switching section. There is a problem that the switching is performed.

The reason is as follows.

On the transmitting side, the two phase information adding sections for the working system and the protection system independently add phase information, and the phase information adding section converts the input signal on the transmitting side into the working system and the protection system of the transmission line. The signal is transmitted to both of the selection units, but the signal phase between the phase information addition unit and the selection unit is not managed.
Therefore, the phases of the working system signal and the protection system signal input to the selection unit are not necessarily matched, and are generally different.

As described above, when the switching of the selecting unit on the transmitting side is performed when the phases of the working system signal and the protection system signal are different, discontinuity occurs in the data sequence in the signal. A signal error occurs in both the working system and the protection system on the receiving side of the instantaneous interruption switching section. As a result, on the receiving side, the error monitoring unit detects this error and controls the selecting unit to perform switching.

[0013] An object of the present invention is to solve the above-mentioned problem, so that even when a switching operation for a transmission-side input outside the instantaneous interruption switching section occurs, an unnecessary switching operation of the transmission line within the instantaneous interruption switching section is performed. It is an object of the present invention to provide an instantaneous interruption switching system capable of improving transmission quality and maintainability by avoiding the above problem.

[0014]

The instantaneous interruption switching system according to the present invention employs a redundant configuration of an active system and a standby system on a transmission line, inserts a predetermined frame pattern on a transmitting side, and transmits on a receiving side. The phase difference between the working system and the standby system is adjusted using the frame pattern inserted on the receiving side, and is temporarily stored in a memory at an output terminal on the receiving side, and a bit error of a signal input to the memory is monitored to detect an error. In the instantaneous interruption switching system in which the transmission path is switched between the working system and the protection system before the signal including the error is output from the memory when the detection is performed, each of the working system and the protection system input on the transmission side is used. After adjusting the phase difference between the signals, one of the input systems is selected as the active system and transmitted to the receiving side via the transmission lines of the two active / standby systems.

As described above, after adjusting the phase difference between the respective signals of the working system and the protection system input on the transmission side, selection switching between the working system and the protection system input on the transmission side is performed. The switching between the signal of the standby system and the signal of the standby system are in phase with each other, so that even if a switching operation is performed on the transmission-side input outside the non-interruptible switching section, the signal does not change on the transmission line in the non-interruptive switching section.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a functional block diagram showing an embodiment of the present invention. In the instantaneous interruption switching method shown in FIG.
The transmitting side and the receiving side have a function for each of the transmission lines of the working system and the protection system.

On the transmitting side, IFs 1 and 2 and phase information adding sections 3 and 3 are provided for the input working system and protection system, respectively.
4, phase adjusters 5 and 6, selectors 7 and 8, and IFs 9 and 1 for the working system and the protection system of the transmission path, respectively.
0 is provided.

In the receiving unit, the IFs 11 and 12 and the phase adjusting unit 1 are used for the active system and the standby system of the transmission path.
3, 14, error monitoring units 15, 16 and memory unit 1
It is assumed that selectors 19 and 20 are provided for the active system 7 and the output system 18 and the output system, respectively.

The difference from the prior art is that the phase information adding units 3 and 4
That is, the phase adjusters 5 and 6 are inserted between the selectors 7 and 8.

The IF 1 receives a signal input from the working system from outside the non-interruptible switching section and sends it to the phase information adding section 3. IF1
The phase information adding section 3 adds phase information for delay time adjustment of instantaneous interruption switching to the signal received from the
6 is output to both. Similarly, the IF 2 receives a signal input by the standby system from outside the non-interruptible switching section and sends it to the phase information adding unit 4. It is assumed that the phase information adding unit 4 adds the phase information for delay time adjustment of the instantaneous interruption switching to the signal received from the IF 2 and outputs the signal to both of the phase adjusting units 5 and 6.

In general, a frame pattern having a cycle sufficiently longer than the transmission path delay time difference between the working system and the protection system in the non-interruptible switching section uses an unused bit portion in the data signal as information to be added. And inserted. The phase information adding sections 3 and 4 mutually transmit and receive timing signals, and add phase information at the same timing.

The phase adjuster 5 receives signals from the outside of the instantaneous interruption switching section, which are input by the working system and the standby system and to which phase information is added, from both the phase information adding units 3 and 4, adjusts the phase, and synchronizes. And sends it to the selection unit 7 by the input working system and standby system, respectively. Similarly, the phase adjuster 6 receives signals from the outside of the non-interruptible switching section by the working system and the standby system and to which phase information is added, from both of the phase information adding units 3 and 4, adjusts the phase, and synchronizes. Therefore, it is assumed that the input is transmitted to the selection unit 8 by the active system and the standby system.

The selection unit 7 receives the input of the working system and the protection system, which have been synchronized by phase adjustment, from the phase adjustment unit 5.
According to FIG. 1, it is assumed that the active system input is selected and transmitted to the active system on the transmission line via the IF 9. Similarly, the selection unit 8
Receives the input of the working system and the protection system synchronized with the phase from the phase adjustment unit 6, while selecting the input of the working system according to FIG. 1 and sending it to the protection system of the transmission line via the IF 10. It shall be.

Each of the selectors 7 and 8 is a part for executing redundant system switching of a transmission line at a stage preceding the instantaneous interruption switching section formed by the instantaneous interruption switching system, and always selects the same system mutually. Is controlled. As a result, in the instantaneous interruption switching section, signals of the same system on the input side are always transmitted to the working system and the protection system of the transmission line.

On the other hand, in the receiving section, the IF
A phase adjustment unit 13 that inputs a signal via the phase adjustment unit 11 uses the phase information added by the phase information addition unit 3 (in the case of FIG. 1) on the transmission side or the phase information added by the phase information addition unit 4. 14 are output to the error monitoring unit 15 and the memory unit 17 with their signal phases aligned. Similarly, the phase adjusting unit 14 that inputs a signal via the IF 12 uses the phase information inserted by the phase information adding unit 3 (in the example of FIG. 1) or the phase information adding unit 4 on the transmitting side to use the current system. Phase adjuster 13
Are output to the error monitoring unit 16 and the memory unit 18 with their signal phases aligned.

The error monitoring unit 15 monitors an error of the signal received from the phase adjustment unit 13, and when an error is detected, controls the selection units 19 and 20 to immediately switch to a system in which no error has occurred. Instructed. Similarly, the error monitoring unit 16
Monitors the error of the signal received from the phase adjustment unit 14,
When an error is detected, the selectors 19 and 20 are controlled to immediately instruct switching to a system where no error has occurred.

It is assumed that an error detection code added to the phase information adding sections 3 and 4 of the transmitting section together with the phase information and used for error detection such as a parity code is used for error monitoring.

The memory unit 17 has a delay of a fixed time between the time when the error is detected by the error monitoring unit 15 and the time when the selection units 19 and 20 are switched, so that the signal containing the error is not transmitted downstream. The buffer memory to give. Similarly, the memory unit 18 provides a delay of a fixed time between the detection of the error by the error monitoring unit 16 and the switching of the selection units 19 and 20 so that the signal containing the error is not transmitted downstream. The buffer memory to give.

The selecting section 19 receives the two signals output from the memory sections 17 and 18, selects one of the signals, and transmits the selected signal to the active system on the receiving side. , The selection of the signals output from the memory units 17 and 18 is immediately switched. Similarly, the selection unit 20 receives the two signals output from the memory units 17 and 18, selects one signal, and sends it to the standby system of the output on the receiving side. Switches the selection of the signal output from the memory units 17 and 18 immediately.

The signals output from the phase adjusters 13 and 14 have the same contents and the same phase, and given a fixed time in the memory units 17 and 18, so that the selecting unit 1
The phases of the signals input to the transmission lines 9 and 20 from the working system and the protection system of the transmission line respectively match. Therefore,
Even if switching is performed by each of the selection units 19 and 20, an instantaneous interruption of the output signal does not occur.

[0032]

Next, the phase relationship on the receiving side in FIG. 1 will be specifically described with reference to FIG. 1 and FIG.

Normally, the transmission path lengths of the working system and the protection system are not necessarily the same, and the delay time of each of the IFs 1 and 2 of the transmission side input varies somewhat. With this signal, the same transmitted information does not always arrive at exactly the same time.

The transmission signal is generally time-division multiplexed with various management information in addition to the information signal. In the hitless switching method, a part of these management information bits is used, a frame pattern is formed as phase information and transmitted from the transmitting side, and the receiving side performs phase adjustment based on the frame pattern. .

Each of the frame synchronization bit F, the information bit I, the spare bit R, and the phase adjustment frame synchronization bit P shown in FIG. 2 has a size of 1 byte, and is F byte, I byte, and R byte, respectively. , And P bytes.

In the instantaneous interruption switching section in the instantaneous interruption switching system, the transmitting unit inserts P bytes, and the receiving unit performs phase adjustment using the P bytes to realize instantaneous interruption switching. As in the case of the instantaneous interruption switching in the receiving unit, by providing the phase adjusting units 5 and 6 in front of the selecting units 7 and 8 of the transmitting unit, the phases of the signals input to the selecting units 7 and 8 can be aligned. .

As shown in FIG. 2A, the signals input to the active / standby phase information adding sections 3 and 4 are slightly shifted in time irrespective of the same contents.
In (A), a shift of one byte occurs. The input signal includes, in addition to the I byte of the information signal, an F byte for separating the I byte of the information signal from various management information signals and a spare R byte that is not used, in addition to the I byte of the information signal, for synchronizing the I byte of the information signal from various management information signals. It is included.

As shown in FIG. 2B, in each of the phase information adding units 3 and 4, a P byte for phase adjustment is inserted at the R byte position and output. In the receiving unit, the phase adjusting units 13 and 14 cooperate to synchronize the frames using the P bytes inserted on the transmitting side and use a built-in buffer memory to determine the delay time difference caused by the difference in the length of the transmission path. Is absorbed.

As shown in FIG. 2C, the phase adjusters 5 and 6 on the transmitting side also perform the phase adjusting process using P bytes, similarly to the phase adjusters 13 and 14 on the receiving side, and the selecting unit 7 , 8 are transmitted to each other.

According to the above-described processing, when the transmission paths are switched by the transmission-side selectors 7 and 8, discontinuity does not occur in the signal train transmitted to the instantaneous interruption switching section. Therefore, when the transmission paths are switched by the selection units 7 and 8 on the transmission side, the error monitoring units 15 and 16 do not detect an error, and extend to the switching operation for detecting the error and switching the instantaneous interruption switching section. Is prevented.

In the above description, a new function is added by performing the same phase adjustment as the phase adjustment on the receiving side using the P-byte for instantaneous interruption used in the instantaneous interruption switching section of the target transmission line. In order to minimize, the phase adjustment unit on the transmission side is provided after the phase information addition unit and before the selection unit, but the phase adjustment unit on the transmission side is provided on the input side of the transmission side selection unit. By performing phase adjustment using information in place of the P byte, such as the F byte, it is possible to avoid error detection due to the switching operation of the transmission-side selector as in the above description.

[0042]

As described above, according to the present invention, the active system and the standby system which are input to the non-interruptible switching section of the transmission line are switched to the active system of the non-instantaneously switching section of the transmission line. It is possible to obtain an effect that it is possible to prevent unnecessary switching with the standby system.

The reason is that the phase of the signals of the working system and the protection system is adjusted by adjusting the phase of the signals of the working system and the protection system before the selector for switching between the working system and the protection system to be inputted on the transmission side of the instantaneous interruption switching section of the transmission path. This is because the phase difference between the two signals is absorbed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart showing one form of an input / output signal of a main part in FIG.

FIG. 3 is a block diagram showing an example of the related art.

[Explanation of symbols]

1, 2, 9, 10, 11, 12 IF (interface unit) 3, 4 Phase information adding unit 5, 6 Phase adjusting unit 7, 8, 19, 20 Selecting unit 13, 14 Phase adjusting unit 15, 16 Error monitoring unit 17, 18 Memory section

Claims (3)

[Claims] 1. A redundant configuration of a working system and a protection system is taken on a transmission line, a predetermined frame pattern is inserted on a transmitting side, and a working system is used on the receiving side by using the frame pattern inserted on the transmitting side. The phase difference between the signal and the standby system is adjusted, the signal is temporarily stored in a memory at an output terminal on the receiving side, and a bit error of a signal input to the memory is monitored. When an error is detected, a signal including the error is output from the memory. In the instantaneous interruption switching system in which the transmission path is switched between the working system and the protection system before the transmission is performed, the phase difference between the signals of the working system and the protection system input on the transmitting side is adjusted, and then one of the input is used. A non-instantaneous interruption switching method, comprising a procedure of selecting a system and transmitting the selected system to the receiving side via transmission lines of two working / standby systems. 2. The method according to claim 1, wherein the step of adjusting the phase difference includes inserting the predetermined frame pattern into each signal input from each of a working system and a protection system of a transmission-side input, and one of the transmission-side inputs. A non-instantaneous interruption switching system, which is performed before selecting a current system as a working system and outputting the selected system to a working system / standby system of a transmission path. 3. A non-instantaneous interruption switching system for switching between an active system and a standby system of a transmission line having a redundant configuration of an active system and a standby system without instantaneous interruption, the transmission side of the transmission line transmits a predetermined signal to an input signal. Are provided for each of the working system and the protection system input from the transmission side, and are received from each of the two phase information adding units. A phase adjustment unit that adjusts and outputs the phase difference between the two output signals, and a selection unit that selects one of the signals that have received the two signal outputs of the phase adjustment unit and outputs the signal to one of the transmission paths. On the receiving side of the transmission line, a memory unit for receiving and temporarily storing a signal input from the transmission line, and monitoring a bit error of a signal input from the transmission line on the receiving side of the transmission line. D An error monitoring unit for instructing switching between the working system and the protection system of the transmission line when an error is detected, provided in each of the working system and the protection system of the transmission line, and receiving one of the output signals from the two memory units, A non-instantaneous-interruption switching method characterized in that a selection section for selecting and setting a reception side output of a transmission path is provided in each of a working system and a protection system of a reception side output.