JPH01236840A - Line switching system - Google Patents

Abstract

PURPOSE:To attain line switching without malfunction by sending a prescribed pattern signal including a supervising control signal to an excess bit after the line is switched when respective intermediate repeaters of the systems in current use receive a switching control signal and the abnormality of an input signal is detected. CONSTITUTION:A means to detect the abnormality of an input signal and output a switching request signal A is provided for the terminal repeater 20 (or a terminal repeater 30) of the system in current use. When respective present use system intermediate repeaters 40 (or intermediate repeater 50) receive a switching control signal and the abnormality of the input signal is detected, a prescribed pattern signal including a supervising control signal is sent to an excess bit after the line is switched. Thus, the termination repeater 20 can surely detect the input signal and can execute the line switching without a malfunction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to a line switching system of a relay device for data transmission. In particular, an intermediate repeater having means for branching and inserting a supervisory control signal using surplus bits of a transmission line code, and for switching to sending a predetermined pattern signal from within and inserting a supervisory control signal when an input signal is abnormal; The present invention relates to a line switching system from a working system to a protection system of a relay device including a terminal repeater having means for transmitting and receiving a supervisory control signal using surplus bits of a transmission line code.

〔overview〕

The present invention provides a line switching system in which when a terminal relay station detects a manual abnormality, it sends a line switching request signal to a line switching device to switch the line, and performs a predetermined process to clearly identify the location of the failure. By sending the pattern signal after switching the line, the terminal repeater can reliably detect manual abnormalities.
This allows line switching to be performed without malfunction.

[Conventional technology]

Conventionally, in the line switching system, a supervisory control inkface circuit that collects various supervisory control signals and performs multiplexing or separation operations is connected to end station repeaters and intermediate repeaters, and the end station repeaters perform multiplexed monitoring and control signals. The control signal is transmitted and received using the surplus bits of the transmission line code, and the intermediate repeater performs branching and insertion using the surplus bits of the transmission line code, and transfers the own station's monitoring signal to or from the terminal station. control signals can be received. When an intermediate repeater detects an input signal disconnection or frame synchronization loss due to a transmission path fault, the fault spreads to the intermediate section after the faulty relay section, and the fault information is transferred and the monitoring control of the normal intermediate section is interrupted. In order to prevent this from occurring, a predetermined pattern signal (hereinafter referred to as the AIS signal) is sent from a predetermined pattern generation circuit inside each device to the rear intermediate repeater.
By receiving the signal, a switching request signal is sent to the line switching device to switch the line.

Also, when the fault in the transmission line is restored and the signal is restored, the intermediate repeater switches the outgoing signal from the AIS signal back to the signal received from the transmission line, but at this time, the frame synchronization of the re-entered signal is established Moreover, the cutback was performed only after the transmission line quality had recovered to a certain level. Moreover, in this case, since the rXi recognizes that the transmission path has recovered more reliably and then switches back, the transmission path failure may fluctuate near the input signal disconnection, or the transmission path quality may fluctuate near the threshold value, causing AIS. To prevent signal switching and switching back from being repeated, a protection time was provided for switching back.

In other words, after detecting an input abnormality and switching to an AIS signal, the manual abnormality is canceled, and if the input abnormality does not occur again within a certain protection time and the transmission path quality is above a certain level, the transmission path is switched back. It became.

[Problem that the invention seeks to solve]

However, in such conventional line switching systems, when the signal is cut off due to a failure in the transmission path, the input signal is cut off almost simultaneously at all intermediate repeaters after the point of failure, and the output of each intermediate repeater that detects the input abnormality is Switch to AIS signal. The intermediate repeater on the receiving side of the faulty relay section will use A until the fault is recovered.
After continuing to send IS signals, the intermediate repeater in the relay section in the normal state receives the AIS signal from the previous intermediate repeater, establishes frame synchronization, and then transmits the AIS signal after the protection time Tg described above. Instead of the AIS signal emitted from inside the repeater, the AIS signal received from the previous intermediate repeater is relayed and sent out. Note that here we are considering the case where a failure occurs only at the one location mentioned above, and we assume that there is no failure at all in the other relay sections and that they are normal, so the input signal to each intermediate repeater is interrupted once. The time from when the AIS signal is input until it is sent out can be considered Tg.

Actually, the protection time Tg is normally set to a time sufficiently longer than the frame synchronization recovery time.

The intermediate repeater on the receiving side of the failed relay section is set as intermediate repeater 1, and the intermediate repeaters connected thereafter are sequentially set as intermediate repeater 2.
, intermediate repeater 3, intermediate repeater 4, intermediate repeater 2
Then, after detecting a human error, AIS from intermediate repeater 1
As mentioned above, it takes about Tg from receiving the signal to transmitting it. However, intermediate repeater 3 receives the AIS signal from intermediate repeater 2, synchronizes the frame, and maintains the protection time T.
g, and then sent to the intermediate repeater 4, but at this time, the AIS signal sent from the intermediate repeater 2 changes from the AIS signal sent from inside the intermediate repeater 2 to the AIS signal sent from the intermediate repeater 1. When switching to , intermediate repeater 3 loses synchronization, an input error occurs, and the output signal becomes A from the internal
The signal is switched to the IS signal, and then the frame synchronization of the AIS signal is performed manually, and the switch is switched back after the protection interval Tg. Therefore, it takes approximately 2 Tg for the intermediate repeater 3 to send out the AIS signal from the intermediate repeater 1 and stabilize after detecting a manual abnormality. The above-mentioned phenomenon also applies to subsequent intermediate repeaters, and intermediate repeater n (n=2.3.4.5) requires a maximum of approximately (n-1)·Tg to stabilize.

Generally, the protection time Tg is set to a sufficiently long time compared to the frame synchronization recovery time, so when n is sufficiently large, (n-1) Tg becomes a sufficiently long time. Although the AIS signal is sent from each intermediate repeater to prevent the fault in the faulty relay section from spreading to the subsequent repeater sections, the above-mentioned fault spreads transiently and the signal received by the end station repeater reaches the maximum (
n-1) - Tg becomes unstable over time. This means that even if one intermediate repeater detects an extremely short input abnormality, the time width in which the input abnormality occurs will be expanded to (n-1) Tg at the terminal repeater on the receiving side. The end station repeater detects an abnormality in the input signal based on such an unstable received signal and sends out a switching request signal, which has the disadvantage of causing malfunctions.

The present invention solves the above-mentioned drawbacks, and aims to provide a line switching method in which a terminal repeater can reliably detect manual abnormalities and can switch lines from the active system to the protection system without malfunction. shall be.

[Means for solving problems]

The present invention provides a line switching system in which each terminal relay station in the working system includes means for detecting an abnormality in an input signal and outputs a switching request signal, and each intermediate repeater in the working system controls switching. The present invention is characterized in that it includes means for transmitting a predetermined pattern signal including a supervisory control signal in surplus bits after switching the line if an abnormality in the input signal is detected when the signal is received.

[Effect]

When the active terminal relay station detects an abnormality in the input signal, it provides a switching request signal to the line switching device of its own terminal station. In accordance with this switching request signal, the line switching device outputs a switching control signal as a supervisory control signal to the terminal repeater of its own terminal station, and transmits it to the other end layer via the transmission path and intermediate repeater. The line switch performs switching between the working system and the protection system based on a switching request signal or a switching control signal from the other end layer. When the active intermediate repeater receives the switching control signal, if it detects an abnormality in the input signal, it sends a predetermined pattern signal (AIS signal) containing the supervisory control signal to the surplus bits on the transmission path after switching the line. Send to. Through the above operations, the terminal relay station can reliably detect the input signal and can perform line switching without malfunction.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. The figure is a block configuration diagram of a line switching control device according to an embodiment of the present invention. In the figure, the line switching control device switches two end-office repeaters 20.30 for the working system and the standby system, and connects the working end-office repeater and the end-office repeater for the standby system to the intra-office transmission line β. Two opposing terminal stations 10. ．． 10. and a plurality of intermediate repeaters 40 connected via transmission lines between the opposing terminal repeaters 20 and 30.
．． 50, a terminal repeater 10 and an intermediate repeater 40
．． Each of 50 includes supervisory control ink face circuits 21, 31, 41, and 51 as a means for inserting and branching supervisory control signals and transmitting/receiving them using surplus bits of the transmission line code, and intermediate repeaters 40, 50 are intermediate relays. Circuit 42.43
．． 52 and 53, and the line switching device 11 switches the current terminal station repeater 20 (or terminal station repeater 30) based on the switching request signal A of the active system terminal station repeater 20 (or It includes means for supplying a switching control signal B as a supervisory control signal to the repeater 30), and means for switching between the active system and the standby system based on the switching request signal A or the switching request signal of the other end layer.

Here, a feature of the present invention is that the terminal station repeater 20 (or terminal station repeater 30) of the working system includes means for detecting an abnormality in the input signal and outputting the switching request signal A. If each intermediate repeater 40 (or intermediate repeater 50) detects an abnormality in the input signal when receiving the switching control signal, it sends a predetermined pattern signal containing the supervisory control signal to the surplus bits to switch the line. The purpose of the present invention is to include means for transmitting the information later.

The operation of the line switching device having such a configuration will be explained.

In the figure, line switching device 11. ．． The intra-office transmission lines βI and R2 connected to the line switch 11. ．． 112
The end station repeater 21 constitutes the working system. ．． 212. The signal on the intra-office transmission line A' 11 is transmitted to the line switch 11. The signal is inputted to the terminal repeater 20° via intermediate repeater circuits 421 to 423, received by the terminal repeater 202, and sent to the intra-office transmission line β21 via the line switch 112. Similarly, the intra-office transmission line β22
The signals of line switching SO2, terminal station repeater 20□, intermediate relay circuits 433, 43□, 434, terminal station repeater 201 and line switching device 11. The signal is sent to the intra-office transmission path β12 via the .

The end station repeaters 112 and 112 each use opposing supervisory control ink face circuits 211 and 212 to connect the end station 10. ．． Similarly, each intermediate repeater 40.10□ transmits and receives monitoring control signals. -403, the supervisory control ink face circuits 411-413 are used to branch and insert the supervisory control signal, and the supervisory control signal of the own station is sent to the terminal station 10. ．． 10□
Transfer to and receive from. Line switch 11. ．． 11□
are terminal repeaters 20. and 20. respectively. ．． The terminal repeater 30.202 receives the switching request sent when the input abnormality is detected.
, 30° and intermediate repeaters 501 to 503 (the connection with the intra-office transmission line p1.12 is switched to the 111 system).

Suppose now that the intermediate relay circuit 42° detects a human power abnormality. At this point, the intermediate repeater circuit 422 does not send out the AIS signal, so the intermediate repeater circuit 423 and the terminal repeater 20
2 detects human power abnormalities. When the terminal repeater 20□ detects a manual abnormality, it sends a switching request signal A 22 to the line switching device 11□, and the line switching device 11□ switches the line to the backup system and performs the switching control shown in the figure. Signal B22
is sent to the monitoring control ink face circuit 212. The switching control signal B22 is sent to the supervisory control interface circuit 212,
The signal is sent to the supervisory control interface circuit 211 via the terminal repeater 20□, the intermediate relay circuit 423, the intermediate repeater circuit 422, the intermediate repeater circuit 4211, and the terminal repeater 20□.
The supervisory control ink face circuit 211 decodes and obtains the switching control signal C2□, and sends it to the line switch 111. The line switch 11 that received the switching control signal C2+. switches the intra-office transmission line β1 from the working system to the protection system. The above completes the switching from the working line to the protection line.

Next, supervisory control ink face circuits 41 . ．． 4h, 41
, but the switching control signal B2□ is decoded and each intermediate relay circuit 4
23.422.42. Send to.

Each intermediate relay circuit 421 to 4 that received the switching control signal B2□
The intermediate relay circuit detecting an input abnormality from 23 (in this case, the intermediate relay circuit 42..423') sends out the AIS signal generated by the built-in ATS generation circuit to the transmission line after switching the line. .

As described above, after the line is switched, it is possible to transfer the supervisory control signal of the intermediate repeater that detected an input signal abnormality and the intermediate repeater below the intermediate repeater that detected the abnormality to the terminal station. Become.

In addition, in consideration of the case where a failure occurs in both directions of the working line, the switching signal from the line switching device is transmitted in two lines together with the working line using, for example, surplus bits on the protection line to ensure line switching. You can also do it. Furthermore, even if the intermediate repeater does not receive a switching control signal, it always switches to the AIS signal after a certain period of time (for example, slightly longer than the maximum time required for line switching) after detecting an input abnormality. By doing so, it is possible to prevent an intermediate repeater that detects a manual abnormality from switching to an AIS signal.

〔Effect of the invention〕

As described above, the present invention has excellent effects in that the terminal repeater can reliably detect manual abnormalities and can perform line switching without malfunction.

[Brief explanation of the drawing]

The figure is a block configuration diagram of a line switching device according to an embodiment of the present invention. 101.102... terminal station, 118.112... line switch, 20, . 20□, 30. ．． 30□...Terminal repeater, 401-403.501-503...Intermediate repeater, 411-41. ．． 51. ~513...Monitoring control ink face circuit, 421~423.43°~43. ．．
52. ~52. ．． 53. ~53□・・・Intermediate relay circuit,
A2+s A22, A31, A32...Switching request signal, B21, B2□, B31, B32, C2+, C2□,
C31, C3□...Switching control signal.

Claims (1)

[Claims] 1. Two opposing terminal stations including two terminal station repeaters and a line switch for the working system and the protection system, and the opposing terminal station repeaters are connected via a transmission line. each of the terminal station repeater and the intermediate repeater includes means for inserting and branching a supervisory control signal using surplus bits of the transmission line code to transmit and receive the signal; The switching device includes a means for providing a switching control signal as a monitoring control signal to the terminal station repeater based on a switching request signal of the terminal station repeater in the active system of the own terminal station, and a means for providing a switching control signal as a monitoring control signal to the terminal station repeater based on the switching request signal of the terminal station repeater of the active system of the own terminal station, and a means for providing the switching control signal as a monitoring control signal to the terminal station repeater, In a line switching system including means for switching between a working system and a protection system based on a control signal, each terminal relay station of the working system includes means for detecting an abnormality in an input signal and outputting a switching request signal, Each intermediate repeater in the active system is provided with means for transmitting a predetermined pattern signal containing a supervisory control signal in surplus bits after line switching if an abnormality in the input signal is detected when receiving the switching control signal. A line switching method characterized by including: