JP2746203B2 - Transmission path non-stop switching system and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for instantaneously switching transmission lines, and more particularly, to a transmission line without instantaneous interruption in which one of a plurality of active transmission lines is switched to a standby transmission line without interruption. The present invention relates to a switching system and method.

[0002]

2. Description of the Related Art Conventionally, a switching system for switching a 1: 1 redundant transmission line in which one active transmission line is provided for one active transmission line without instantaneous interruption is shown in FIG. (For example, Japanese Patent Application Laid-Open No. 4-243335).
Issue publication). The main signal input to the transmitting device 50 is inserted with a predetermined identification signal by an identification signal insertion unit 51, is branched by a branching unit 52, and the same main signal is output to the working transmission line L10 and the protection transmission line L11. You.

The time difference between the two main signals is detected by the time difference detecting section 61 of the receiving apparatus 60 based on the identification signals inserted into the main signals of the working system and the standby system, and each delay is controlled by the control section 62 based on the time difference. The delay times of the units 63 and 64 are controlled. As a result, the time difference between the active system and the standby main signal output from the delay units 63 and 64 is eliminated, and the switching unit 65 switches from the active system to the standby system without interruption.

[0004]

Therefore, such a conventional transmission line non-stop switching method is applied to a 1: N redundancy system in which one protection transmission line is provided for a plurality of active transmission lines. When used for the system transmission line, the delay time is controlled as one set of the working system and the protection system.
Since the delay time of each working system differs depending on the line length, etc., the delay time of the commonly used protection system is not determined, and the control of the delay unit provided on the receiving side of each transmission line becomes complicated. In addition, when the speed of the main signal is higher, there is a problem that the processing delay may affect the main signal. The present invention is intended to solve such a problem, and a transmission line non-interruptible switching system and method capable of realizing non-interruptible switching in a 1: N redundant transmission line with simple delay control. It is intended to provide.

[0005]

In order to achieve the above object, a transmission line non-stop switching system according to the present invention comprises:
On the transmitting side, reference frame signal superimposing means for superimposing a predetermined reference frame signal on the working main signal output to each working transmission line, and any of the working main signals on which the reference frame signal is superimposed. And first switching means for selecting the active system and outputting the standby system main signal to the standby system transmission line. The first switching unit is provided on the receiving side for each of the active system transmission line and the standby system transmission line. A buffer memory for temporarily storing a main signal and a standby main signal, and a first main signal interface provided for each active transmission line and performing write control for writing each active main signal to a corresponding buffer memory Means and write control for writing the standby system main signal into the corresponding buffer memory, and all buffers are controlled at the same timing based on the reference frame signal superimposed on the standby system main signal. Second main signal interface means for performing read control for reading the active main signal and the standby main signal stored in the active memory, and provided for each active transmission line, each active main signal and the standby main signal. A second switching means for selecting and outputting any one of a signal and a signal provided between the first switching means and the second main signal interface means. And a delay means for delaying the standby system main signal so that the reception phase of the signal is the most delayed.

Further, the method for instantaneously switching transmission lines according to the present invention is characterized in that, on the receiving side, for each of the working transmission line and the protection transmission line, each of the transmission lines received from each of the working transmission line and the protection transmission line. A buffer memory for temporarily storing the working main signal and the protection main signal is provided, and a predetermined reference frame signal is superimposed on the working main signal output from the transmitting side to each working transmission line. Of the active system main signal on which the reference frame signal is superimposed, select the active system main signal to be switched, transmit it to the standby system transmission line as the standby system main signal, and send it to all the active system main signals. In comparison, a delay is given to the standby main signal so that the reception phase on the receiving side is delayed, and each active main signal and the delayed standby main signal are sequentially stored in each buffer memory on the receiving side. Given the delay At the same timing based on the reference frame signal superimposed on the standby main signal, the active main signal and the standby main signal stored in each buffer memory are read out, and the active main signal to be switched and the standby main signal are read out. One of the system main signals is switched and output.

[0007]

Therefore, a predetermined reference frame signal is superimposed on the working main signal output to each working transmission line from the transmitting side and transmitted, and each working main signal on which the reference frame signal is superimposed is transmitted. The active main signal to be switched among the signals is selected and transmitted to the standby transmission line as a standby main signal, and on the receiving side, each active main signal and the standby main signal to which a delay is given are buffered. The active main signal and the standby main signal stored in each buffer memory are read out at the same timing based on the reference frame signal superimposed on the standby main signal which is sequentially stored in the memory and delayed. Either the active main signal or the standby main signal to be switched is switched and output.

[0008]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a transmission line non-stop switching system according to one embodiment of the present invention. In particular, a 1: N (N = 2) 1: N system including two working transmission lines and one protection transmission line. A redundant transmission line is shown as an example.

In FIG. 1, 1 is a transmitting device, 2 is a receiving device, L0 is a protection transmission line, and L1 and L2 are independent working transmission lines. In the transmitting apparatus 1, reference numerals 11 and 12 denote reference frame signal superimposing sections for superimposing a predetermined reference frame signal on an active main signal of each active transmission line. A switching unit (first switching means) 15 for transmitting any one of the signals as a standby system main signal to the standby system transmission line L0, a standby system main unit 15 on the receiving side as compared with all the active system main signals. This is a delay unit that delays the standby main signal so that the reception phase of the signal is the most delayed.

In the receiving apparatus 2, reference numerals 21 and 22 extract a reference frame signal from a working system and a working system main signal received from the working system transmission lines L1 and L2, and write control signal 3
A main signal interface section (hereinafter, referred to as main signal I / F section: first main signal interface means) for generating and outputting 5, 36 generates a reference frame signal from the standby main signal received from the standby transmission line L0. A main signal interface section (hereinafter, referred to as a main signal I / F section: second main signal interface means) that extracts and generates and outputs a write control signal 37 and a read control signal 38; A buffer memory unit for sequentially storing the main signals of the respective transmission paths based on the read control signal and outputting the main signals in the same phase based on the read control signal;
Reference numerals 7 and 28 denote switching units (second switching means) for switching and outputting any of the active system main signal and the standby system main signal.

FIG. 2 shows buffer memory sections 24-26.
In the figure, reference numeral 32 denotes a counter for generating a read address by starting a counting operation from a predetermined value in response to a read control signal 38, and 31 a main signal in order based on a write control signal 35. A buffer memory (elastic store) that stores and outputs the stored main signal based on the read address of the counter 32.

Next, with reference to FIG. 3, a description will be given of the operation of the present invention in which the switching from the working transmission line L1 to the protection transmission line L0 is controlled. FIG. 3 is a flowchart showing a transmission path switching procedure. First, a predetermined reference frame signal is superimposed on each main signal input to the transmitting apparatus 1 by the reference frame signal superimposing units 11 and 12. Here, the switching unit 13 of the transmission device 1 is switched to the working transmission line L1 side,
The same main signal as the main signal of the working transmission line L1 is supplied to the delay unit 15
(Step 41).

In the delay unit 15, a delay amount such that the standby main signal is delayed from all the active main signals in the reception phase of the receiving device 2 is considered in advance in consideration of the dispersion of the delay amount due to each transmission path. The protection main signal is set, and is received by the receiver 2 with a phase delayed from any of the working main signals. Each of the active system main signal and the standby system main signal is received by the main signal I / F sections 21 to 23 of the receiving device 2 and has a predetermined write phase (for example, 6 bits of the received J1 byte).
Write control signal 35 to
37 is generated and written into the buffer memory 31 in the buffer memory units 24-26.

In the main signal I / F section 23 of the standby system,
A read control signal 38 is generated based on the reference frame signal superimposed on the standby main signal and further added with the amount of phase fluctuation of the standby system, and is commonly supplied to the buffer memory units 24 to 26. Therefore, the read control signal 38 based on the reference frame signal of the standby system which is delayed most.
Is output to each of the buffer memory units 24-26,
Buffer memory 3 for each working main signal and standby main signal
1, the main signal is read from the buffer memory 31 to be written based on the read control signal 38 at the same timing (step 4).
2).

In this case, each of the buffer memory units 24-26
Counter 32 always counts at a speed corresponding to the transmission rate of the main signal, and its counter value, that is, the address, is reset in response to the read control signal 38. Generates and outputs a read address. In this way, the active main signal and the standby main signal are stored in each buffer memory unit 24.
To 26 are read out at the same timing, and one is selected and output by the switching unit 27 (step 43).

As described above, the delay unit 15 for delaying the standby main signal is provided so that the standby main signal is delayed most on the receiving side as compared with all the active main signals. Since each of the active main signal and the standby main signal is read from the buffer memory 31 based on the read control signal 38 generated based on the reference frame signal of the signal, even in the 1: N redundant transmission line, Accurate instantaneous interruption switching is realized by relatively simple delay control.

In the above description, a case has been described where the delay unit 15 for delaying the standby main signal is provided in the transmitting apparatus 1. However, the main signal I / F is provided after the switching unit 13.
It may be provided at any stage as long as it is a standby system upstream of the unit 23. For example, even in the case of being provided in the receiving device 2 and upstream of the main signal I / F unit 23, the same operation and effect as described above can be obtained. Become. Also, the case where the active transmission line L1 is switched to the standby transmission line L0 has been described, but the same applies to the case where the active transmission line L2 is switched to the standby transmission line L0 and also when there are many active transmission lines. The operation and effect of the present invention are achieved.

[0018]

As described above, according to the present invention, the delay means for delaying the backup main signal so that the reception phase on the receiving side is the most delayed compared to all the active main signals is provided. The transmitting side transmits a working main signal to be switched, on which a predetermined reference frame signal is superimposed, to the standby transmission line as a standby main signal, and the receiving side delays the standby system by the delay means. Based on the reference frame signal superimposed on the main signal, each active main signal and standby main signal stored in each buffer memory are read out at the same timing, and the active main signal to be switched and the standby main signal are read out. Since any one of the main signals is switched and output, all the working main signals and the standby main signal are output in the same phase without requiring complicated delay control,
Even in a 1: N redundant transmission line, accurate instantaneous interruption switching can be realized with relatively simple delay control.

[Brief description of the drawings]

FIG. 1 is a block diagram of a transmission line hitless switching system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a buffer memory unit.

FIG. 3 is a flowchart showing a transmission path switching procedure.

FIG. 4 is a block diagram of a conventional transmission path non-stop switching system.

[Explanation of symbols]

1 ... Transmission device, 11 and 12 ... Reference frame signal superimposing unit,
13, 14 switching unit (first switching unit), 15 delay unit, 2 receiving device, 21, 22 main signal interface unit (main signal I / F unit: first main signal interface unit), 23 ... Main signal interface (main signal I /
F part: second main signal interface means), 24-2
6 buffer memory section, 27, 28 switching section (second switching means), 31 buffer memory, 32 counter, 3
5 to 37: write control signal, 38: read control signal, L
0: protection transmission line, L1, L2: working transmission line.

Claims (2)

(57) [Claims] The present invention is used for a redundant transmission line in which one protection transmission line is provided for a plurality of active transmission lines connecting a transmission side and a reception side. In a transmission line hitless switching system that switches any one of the system transmission lines to a protection system transmission line, a reference that superimposes a predetermined reference frame signal on the working main signal output to each working transmission line on the transmitting side. Frame signal superimposing means; and first switching means for selecting one of the working main signals on which the reference frame signal is superimposed and outputting the selected main signal to the protection transmission line as a protection main signal. A buffer memory provided for each of the working transmission line and the protection transmission line and temporarily storing the received main and protection main signals, and a buffer memory provided for each of the working transmission lines. Working main signal First main signal interface means for performing write control for writing to a corresponding buffer memory; and reference frame signal for performing write control for writing a standby system main signal to a corresponding buffer memory and superimposed on the standby system main signal. Second main signal interface means for performing read control for reading the active main signal and the standby main signal stored in all the buffer memories at the same timing based on A second switching means for selectively outputting either the working system main signal or the protection system main signal; provided between the first switching means and the second main signal interface means; A transmission line having a delay means for delaying a backup main signal so that a reception phase on the receiving side is delayed most as compared with the main signal. Cross-sectional switching system. 2. A redundant transmission line provided with one standby transmission line for a plurality of active transmission lines connecting a transmission side and a reception side, and is used without instantaneous interruption of a main signal. In the transmission line uninterruptible switching system for switching any of the system transmission lines to the protection system transmission line, on the receiving side, for each of the working system transmission line and the protection system transmission line, each of the working system transmission line and the protection system transmission line A buffer memory is provided for temporarily storing each of the active main signal and the standby main signal received from the transmission line, and a predetermined reference is made to the active main signal output from the transmission side to each of the active transmission lines. The superimposed frame signal is transmitted, and the active main signal to be switched is selected from among the active main signals on which the reference frame signal is superimposed, and transmitted as a standby main signal to the standby transmission line. Compare with the current main signal Then, a delay is given to the backup main signal so that the reception phase on the reception side is delayed. At the reception side, each working main signal and the standby backup main signal given delay are sequentially stored in each buffer memory, At the same timing based on the reference frame signal superimposed on the delayed standby main signal, each active main signal and standby main signal stored in each buffer memory are read out,
A method for non-instantaneous transmission line switching, wherein one of the working main signal and the standby main signal to be switched is switched and output.