JPS60154734A - Fault detection system of inserting and branching device - Google Patents

Abstract

PURPOSE:To attain the detection of a fault by devices at both sides by supervising in polarity at the counter station warning signal of a digital multiplexer, passing through the signal when an inserting and branching device is failed, and eliminating the inversion of the counter station warning signal. CONSTITUTION:DMUX11, MUX12 are provided respectively with a counter station warning extracting circuit and a counter station warning inserting circuit being used for a digital multiplexer. Then the counter station warning signal having a level of ''0'' at normality and of inverted ''1'' at fault, extracted via the counter station warning extracting circuit is supervised by a counter station warning signal supervisory circuit 13, and the signal is inverted by an inversion circuit 14 and inserted via the counter station warning insertion circuit an the result is transmitted to the next stage from the MUX12.

Description

Detailed Description of the Invention (a1 Technical Field of the Invention) The present invention relates to a digital communication system having opposing add/drop devices between opposing digital multiplexers, and in the event of a failure in the add/drop devices, at least the devices on both sides The present invention relates to a fault detection method for an insertion/drop device that enables fault detection in the present invention.

Background of the technology An add/drop device is a device that transmits data using an empty channel of a digital multiplexer.It has the same frame structure as the digital multiplexer, and in the event of a failure, it can be used as a through bus. It has become.

The game alarm signal is a signal that notifies the other party's digital multiplexer of a fault in the digital multiplexer. It uses a bit at a specific position in the frame. In the event of a fault, this bit is inverted and the other party's The problem is becoming obvious. For example, a "0" signal is sent when consolidation occurs, and an inverted "1" signal is sent when a failure occurs.This allows the digital multiplexing device on the other end to detect the failure. It has become.

(C) Prior Art and Problems FIG. 1 is a block diagram of a communication system using a conventional add/drop device, and FIG. 2 is an explanatory diagram of through-path operation when the add/drop device fails.

In the figure, 1 and 2 are digital multiplexers, 3 and 4 are add/drop devices, 5.6 is a signal add/drop unit, 1o is an add/drop unit, and S
WI~SW4 are switches, 7-1°7-2.8-1.8
-2.9-1.9-2 indicates a transmission path.

In FIG. 1, one-way data transmission will be explained as a representative example. Data multiplexed by digital multiplexer 1 is transmitted through transmission path 7-1. Add/drop device 3, transmission line 8-1.
Insertion/branching device 4. The signal is transmitted to the digital multiplexer 2 through the transmission path 9-1. Further, a game warning signal is also transmitted from digital multiplexer 1 to 2 through the same route. On the other hand, between the add/drop devices 3 and 4, the digital multiplexers 1 and 2
Data communication is performed between the signal insertion/branching units 5 and 6 using empty channels with the same frame structure.

In the case of a failure, the insertion/branching devices 3, 4 switch the switches SW1 to SW'4 from the solid line side to the dotted line side, as shown in FIG. 2, so that the insertion/branching section 10 is passed through.

For example, if the insertion/dropping device 3 becomes a failure,
The insertion/dropping device 3 is a through bus, and to explain one direction as a representative, multiplexed data (including game alarm signals) is transferred from the digital multiplexer 1 to the transmission line 7-1.8-
1, and is sent to the digital multiplexer 2 through the add/drop device 4, but there is a drawback that no other device can detect a failure in the add/drop device 3.

fd1 Purpose of the Invention The purpose of the present invention is to provide a failure detection system for an insertion/branch unit that makes it possible to detect failures with devices on both sides when the insertion/drop unit becomes a failure. be.

(e1 Structure of the Invention) In order to achieve the above object, the present invention provides a means for extracting the game alarm signal of a digital multiplexer using an insertion/branching device and inverting and transmitting the game alarm signal. means for monitoring the polarity of the
If the add/drop device becomes faulty, the system becomes a through bus and the game alarm signal is no longer inverted, making it possible to detect the fault in at least the devices on both sides.

(Example of f1 invention An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram of the main parts of the insertion/dropping device according to the embodiment of the present invention, showing one direction. 1 is a multiplex signal separation unit (hereinafter referred to as DM (JX)), and 12 is a multiplexer (hereinafter referred to as JX). 13 is a game alarm signal monitoring circuit, 14 is an inversion circuit, 15 is a signal branch terminal, and 16 is a signal insertion terminal.

In FIG. 3, the multiplexed digital signal is transmitted to the DMU
XII, the signal of the channel used in the add/drop device is taken out from the signal branch terminal, and the other channels are sent to MUX12, and are multiplied together with the signal of the channel used in the add/drop device inputted from the signal insert terminal 16. The signal is multiplexed into a multiplexed digital signal and transmitted to the next stage device. In this case, DMUX11. MUXl
o is provided with a well-known game alarm output circuit and a game alarm insertion circuit used in digital multiplexing devices, respectively, and the output signal taken out through the game alarm output circuit is, for example, "0" in normal operation, but in case of failure. The inverted '1' match alarm signal is monitored by the match alarm signal monitoring circuit 13, inverted by the inverting circuit 14, and inserted via the match alarm insertion circuit M U x
It is designed to be transmitted to the next stage from tO. Of course the second
It has the through-pass function shown in the figure.

Here, it is assumed that the insertion/dropping devices 3 and 4 in FIG.
1'', the flow of the game warning signal will be explained using FIG.

In the upstream direction during normal operation, the game alarm signal of “0” transmitted from the digital multiplexer 1 is sent to the add/drop devices 3 and 4.
The game alarm signal, which has been inverted at 10°, is input to the digital multiplexer 2. On the other hand, in the downstream direction, the game warning signal of "0" transmitted from the digital multiplexer 2 is inverted by the add/drop devices 4 and 3, and the game warning signal of "0" is input to the digital multiplexer 1. In this case, the game alarm monitoring circuit 13 that monitors the game alarm in the upstream direction of the add/drop device 4 and the game alarm monitor circuit 13 that monitors the game alarm in the downstream direction of the add/drop device 3 receive a signal of “1”. We have come to recognize time as compression. Also, the game alarm monitoring circuit 13 that monitors the game alarm in the downstream direction of the insertion/dropping device 4 and the game alarm monitoring circuit 13 that monitors the game warning in the upstream direction of the insertion/dropping device 3 detect when a signal of "0" is coming. It has come to be recognized as normal.

For example, if the add/drop device 3 becomes a failure and is passed through, the game alarm signal input to the add/drop device 4 in the upstream direction becomes 0'', and the game alarm signal input to the digital multiplexer 1 in the downstream direction becomes 0''. It becomes "1", and the game alarm monitoring circuit 13 of the add/drop device 4 and the digital multiplexer 1 on both sides can know the failure of the add/drop device 3.If the add/drop device 4 becomes a failure and a through bus is established. In the same manner as described in Section 2 above, the fault can be detected by the game alarm monitoring circuits 13 of the digital multiplexer 2 and the add/drop device 3 on both sides. Note that devices other than those on both sides can also detect a failure by inverting the game alarm signal.

(According to the present invention, when the add/drop device becomes a failure, the game alarm signal is not inverted because it is passed through the bus, so at least the devices on both sides can detect the failure.) effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a communication system using a conventional add/drop device, FIG. 2 is an explanatory diagram of through-path operation in the event of a failure in the add/drop device, and FIG. 3 is a schematic diagram of an add/drop device according to an embodiment of the present invention. FIG. In the figure, 1.2 is a digital multiplexer, 3 and 4 are add/drop devices, 5.6 is a signal add/drop unit, and 7-1. 7-2.8-1.8-2.9-1.9-2 is the transmission line, 1
0 indicates an insertion/branching section, SWI to SW4 are switches, 11 is a multiplexed signal separation section, 12 is a multiplexing section 13 is a game alarm monitoring circuit, 14 is an inversion circuit, 15 is a signal branching terminal, and 16 is a signal insertion terminal. '! ] I21= article 2 drunkenness tower 3 drunkenness

Claims (1)

[Claims] In a digital communication system having opposing add/drop devices between opposing digital multiplexers, a means for extracting a game alarm signal of the digital multiplexer by the add/drop device and inverting the transmission; 1. A failure detection method for an add/drop device, characterized in that each add/drop device is provided with means for monitoring the polarity of an alarm signal.