JPS6151457B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a failure notification system between a trunk device and a control device of a digital telephone exchange that transmit and receive information while maintaining multiframe synchronization.

In recent years, telephone exchanges have been digitized, and the trunk lines between digital exchanges and existing analog exchanges such as crossbar exchanges are now PCM and FDM.
If multiplexing is not performed, the connection is made using a so-called metallic line. The inter-office signaling system for this metallic line is broadly divided into loop signaling system and SR signaling system, and the loop signal is often converted to SR signal at the entrance of the digital switch, and processed internally as SR signal. It is.
This is to prevent the entire exchange from being affected if the signaling system of the trunk line between the other exchange is changed from, for example, the loop signaling system to the SR signaling system.

FIG. 1 is a system diagram showing an example of a digital switch having such a loop signal and SR signal conversion function in a trunk line interface section. In FIG. 1, reference numerals 101 to 130 are metal trunk lines that use a loop signal system with other exchanges, and 2 is a trunk device that reads the line status of the metal trunk lines 101 to 130, converts it into an SR signal, and sends it to the uplink highway. 3, and conversely, it has a function of converting the SR signal sent via the down highway 3' into a loop signal and sending it to the metallic trunk lines 101-130. 4 is a time-division communication path, 5 is an internal path on the upstream side of the time-division communication path 4 for transmitting information to the control device 7 among the information on the uplink highway 3, and 5' is an internal path from the control device 7 to the trunk device 2. This is an internal path on the downlink of the time-division communication path 4 for sending information to the terminal, and both internal paths are set semi-fixedly. Furthermore, 6 is an up signal highway connecting the time division communication path 4 and the control device 7, 6' is a down signal highway connecting the control device 7 and the time division communication path 4, and the control device 7 is a digital exchange. A device that controls the signal system of
In addition, there is a central control unit (not shown) that controls the entire digital exchange.

The trunk device 2 described above is provided in units of about 30 lines and is realized with a configuration as shown in FIG. In FIG. 2, ATRK is a trunk circuit for terminating the metallic trunk lines 101 to 130 shown in FIG.
Only 01 is shown and the others are omitted. ) and
It monitors the status of audio analog-to-digital conversion and the metallic trunk line, reports the status monitoring results to the trunk control circuit TRKC via the control line S, and also transmits control information from the trunk control circuit TRKC to the control line. It has a function to receive it via S' and send it to the metallic trunk line.

Here, the audio that is digitized by the trunk circuit ATRK via the metallic trunk line 101 is then sent to the inserter I via the communication line V, and is sent to the upstream highway 3 together with the information from the control information register SREG. Ru. On the other hand, the voice and control information sent from the downward highway 3' via the time division communication line 4 are separated by the dropper D, and the voice is transmitted via the communication line V' to the trunk circuit ATRK.
and the control information is sent to the control information register SREG. In these operations inside the trunk device 2, the trunk control circuit TRKC converts loop signals and SR signals, and controls the control information register.
The SREG maintains multiframe synchronization between the storage of control information and the control device 7.

Incidentally, the trunk device 2, time division communication path 4, and control device 7 in the digital exchange shown in FIG. It is known that the length of is very short.

Figure 3 shows the frame configuration of highways 3 and 3'.
This figure shows an example of the correspondence between the multiframe configuration, signaling, and metallic trunk lines. Specifically, one multiframe is composed of six frames, and the multiframe synchronization signal M and the signaling corresponding to each metallic trunk line are transmitted using the #32 time slot (#32TS) of each frame. The control information register SREG in the control device 7 and the trunk device 2 monitors the multiframe synchronization signal M for each frame, establishes multiframe synchronization, and transmits and receives signals.

In the above configuration, for example, the trunk device 2
If a failure occurs, it is necessary to promptly notify the control device 7 of the failure, take measures such as blocking, and have a maintenance person repair the failure. As a notification means in this case, a method of using one of the surplus bits of #32TS in FIG. 3 as an alarm bit can be considered.

However, in this method, the controller 7 must monitor both multiframe synchronization loss and alarm bits, and if there are many trunk devices in the digital exchange, the controller 7 needs to monitor the hardware. The disadvantage is that the amount of hardware and processing increases.

Furthermore, monitoring both multiframe synchronization loss and alarm bits as in the above method is redundant for the following reasons.

(1) Trunk control circuit inside trunk device 2
TRKC and control information storage register SREG can be made extremely compact using recent semiconductor integrated circuits, and the probability of failure is extremely low. Note that the trunk circuit ATRK is provided corresponding to the line, and a failure in this part is generally detected through normal call processing, and is not configured to notify using the method described above.

(2) Generally, the trunk device 2, time-division channel device 4, and control device 7 are installed and operated in the same room or in the same building, and the highways that connect them are short. Since there is no interference induced by power lines or the like, there is a very low possibility that multiframe synchronization will occur due to burst noise or the like.

(3) Failures in commonly used parts of the time-division channel equipment 4, such as time-division switches, are detected online by means such as adding parity to information passing through the time-division channel. This is common, and the probability of a failure related only to a specific time slot occurring is extremely small.
Furthermore, even if a fault occurs, the scope of the fault is small.

The present invention has been made in consideration of the points (1) to (3) above, and is characterized in that the highway connecting devices is short, and information is sent and received in units of multiple frames, and each unit is identified. In a digital switching system that transmits and receives information while maintaining multiframe synchronization for the purpose of , by detecting an abnormal state of the multi-frame synchronization signal in the other control device, a failure in one control device is notified to the other control device.The purpose is to reduce the occurrence of failures in hardware. To provide a means for notification without increasing the amount of processing on the side to be notified. The details will be explained below with reference to the drawings.

Between the trunk device 2 and the control device 7 in FIG.
For example, when information is transferred using a multi-frame synchronization signal "011000" as shown in FIG. When detected, the trunk device 2 sends out a multi-frame synchronization signal, for example, "111111". The control device 7 detects that the multiframe synchronization signal received via the highway 3, internal path 5, and signal highway 6 is not "011000", that is, the multiframe synchronization is lost, and thereby knows that a failure has occurred in the trunk device 2. be able to. In other words, since the control device 2 can detect a failure in the trunk device 2 by monitoring only the multi-frame synchronization signal, it is possible to simplify the hardware and processing amount of the control device 7.

Note that although a protection time is provided for temporary loss of synchronization, it is usually several milliseconds, and there is no practical problem in the failure notification being delayed to this extent.

The case where the control device 7 is notified of a fault in the trunk device 2 has been described above, but if a fault occurs somewhere in the information path from the control device 7 to the trunk device 2, and as a result, the Even if the frame synchronization signal becomes abnormal, it is possible to notify the control device 7 by making the multi-frame synchronization signal sent from the trunk device 2 abnormal, in the same way as when a failure occurs in the trunk device 2. It is. However, in this case, in the control device 7, the notification from the trunk device 2 is the same "111111" when the multi-frame synchronization signal received by the trunk device 2 becomes abnormal and when a failure occurs in the trunk device 2. ” signal will be received. To be more specific, it is not a failure of the trunk device 2, but an abnormality in the received multiframe synchronization signal, that is, an out-of-synchronization of the multiframe is detected, and the controller 7 receives a signal of "111111", which is different from the signal of "011000". When the maintenance person receives a notification as a signal, the maintenance person first treats it as a fault has occurred in the trunk device 2. In the process, when the maintenance person learns that the above notification does not indicate a failure in the trunk device 2, the maintenance person The multi-frame synchronization signal received at step 2 is notified that the multi-frame synchronization signal has been lost due to burst noise, etc., and the necessary measures are taken. Even with this procedure, in the digital switching system, as mentioned above, the highways connecting each device are short and there is no risk of interference caused by induction from power lines, etc., so there is an extremely high probability that the multi-frames received by the trunk device 2 will be out of synchronization. Moreover, the time delay required for the above-mentioned necessary measures does not cause any problems in system operation.

As explained above, according to the present invention, it is possible to know a failure on the other device or on the path from the own device to the other device by simply monitoring the multi-frame synchronization signal, so a special circuit for failure notification is required. This makes it possible to easily notify failures without having to install a system or increase the amount of processing on the receiving side, and it can be used to notify failures between trunk equipment and call path control equipment in time-division exchanges. You can expect excellent results.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an example of a digital exchange having an SR-loop conversion function, Fig. 2 is a diagram showing an example of the configuration of a trunk device, and Fig. 3 is an explanation of the frame structure on the highway, multiframe synchronization signals, etc. It is a diagram. 101-130...Metallic relay line, 2...
Trunk device, 3, 3'...highway, 4...
Time division multiplex communication path, 6, 6'...Signal highway, 7...Control device, ATRK...Trunk circuit, TRKC...Trunk control circuit, SREG...Control information storage register, I...Inserter, D...
Droppa, V, V'... are communication lines.

Claims (1)

[Scope of Claims] 1. A digital switching system that transmits and receives information by disposing a time-division channel device between a trunk device and a control device, in which each highway connecting each device is short and transmits multiple frames. In the above system that transmits and receives information as a unit and performs multiframe synchronization to identify the unit, as a means for notifying the other of a failure detected in one of the trunk device and the control device. , a failure notification method characterized in that the multi-frame synchronization signal sent from one device is set to an abnormal state, and the other device detects the abnormal state of the multi-frame synchronization signal to notify the fault of one device. .