JPH0533577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fallback control system for relay lines in digital communications. In particular, it relates to a method for automatically performing fallback control in a short period of time.

〔overview〕

The present invention provides a fallback control method for a relay line between a pair of opposing multiplex line concentrators and a modem, in which the multiplex line concentrator performs fallback control on a modem that detects deterioration of the relay line, and at the same time transmits data to the relay line. By controlling the signal to stop, detecting that the opposite station has stopped transmitting, and automatically performing fallback control, it is easy to perform fallback processing when the relay line deteriorates, and the processing time is reduced. It was made to be shorter.

[Conventional technology]

FIG. 2 is a block diagram of a conventional fallback control device. In Figure 2, the low-speed line
The data input via l ₁ is sent to multiple line concentrator 1.
After being multiplexed by , the signals are input to the modem devices 2 ₁ and 2 ₂ via high-speed lines l ₂₁ and l ₂₂ . The signal is modulated by the modem devices 2 ₁ and 2 ₂ and transmitted to the modem devices 3 ₁ and 3 ₂ on the other side via the relay lines l ₃₁ and l ₃₂ . Here, the signal is demodulated and input to the multiplex line concentrator 4, and after error checking is performed by the data determining sections 41 ₁ and 41 ₂ , it is separated for each low-speed line _l5 and transmitted to the outside. Data from the low-speed line _l5 is transmitted to the low-speed line _l1 by a path opposite to that described above.

In the above-mentioned communication equipment, for example, trunk lines l ₇₁ , l ₇₂
When a failure such as a line disconnection occurs, the modem 2 ₁ , 2 ₂ turns off the carrier detection (CD) signals S ₁₁ , S ₁₂ that indicate to the multiplex concentrator 1 that the carrier is being received. , notification of deterioration of trunk lines l ₇₁ and l ₇₂ . As a result, the multiplex concentrator 1 connects the modem 2 ₁ ,
2 ₂ to output fallback control signals S ₂₁ and S ₂₂ to failback the speeds of the modulators 2 ₁ and 2 ₂ . At this point, the speeds of the multiplex concentrator 1 and the modems 2 ₁ and 2 ₂ have fallen back, but the speeds of the multiplex concentrator 4 and the modulators 3 ₁ and 3 ₂ remain in a non-fallback state. It is. Here, the data transmitted from the multiplex concentrator 1 to the modulators 2 ₁ and 2 ₂ is modulated at the fallback speed by the modulators 2 ₁ and 2 ₂ and output to the relay circuits l ₃₁ and l ₃₂ . However, since the modems 3 ₁ and 3 ₂ have not yet reached the fallen-back speed, the high-speed lines l ₄₁ and l ₄₂ have
Normal demodulated data is not output. When this abnormal demodulated data is received, the multiple line concentrator 4 checks whether there is an error in the data in the data determining units 41 ₁ and 41 ₂ based on the number of errors within a certain period of time. If the error is greater than the threshold, a fallback control signal is sent to the modulators 3 ₁ and 3 ₂ as the error is greater than the line.
S ₆₁ and S ₆₂ are output, and the speeds of the modulation and demodulation devices 3 ₁ and 3 ₂ are rolled back. As a result, the speeds of the multiplex concentrator 1, the modulators 2 ₁ and 2 ₂ , the multiplex concentrator 4, and the modulators 3 ₁ and 3 ₂ are all rolled back.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional fallback control device, one of the modulation and demodulation devices falls back,
The other multiplex concentrator detects an abnormality in the received data when the other modem is not performing fallback, and controls the modem based on the result to perform fallback, which makes the process complicated and makes it difficult to perform fallback in one pair. The problem was that it took a long time to complete.

SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks, and aims to provide a fallback control system in which the fallback process is simple and the time required to complete the fallback in one direction is short.

[Means for Solving the Problems] The present invention provides a pair of multiple line concentrators facing each other and accommodating complex low-speed lines, a modem device connected to each of the pair of multiple line concentrators, and a system between the modem devices. and a relay line connecting the modem to the modem, and the modem includes means for detecting line deterioration of the relay line on the input side of the modem and means for notifying the multiplex line concentrator of the detected line deterioration, The multiplex line concentrator includes means for outputting a fallback control signal in response to notification of line deterioration from the corresponding modulation/demodulator, and further includes means for inputting the fallback control signal from the corresponding multiplex line concentrator to the modulator/demodulator for fallback. In the data communication relay circuit fallback control system, the multiplex concentrator is provided with means for outputting a control signal for stopping transmission data to a corresponding modulation/demodulation device upon notification of the line deterioration.

[Effect]

According to the present invention, when line deterioration of a trunk line is detected, the modem turns off the carrier detection signal and notifies the multiplex concentrator. When the carrier detection signal is turned off, the multiplex concentrator generates a fallback control signal and outputs it to the modulation/demodulation device for fallback, and at the same time generates a control signal to stop transmission and outputs it to the modulation/demodulation device. The modem uses this transmission signal stop control signal to
Stop the transmission signal that was being sent. The modulator on the other end detects this and notifies the multiplex concentrator by turning off the carrier detection signal.
In this way, the multiplex concentrator outputs the fallback control signal to its modem, thereby
Fallback processing is simple and processing time can be shortened.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a fallback control device according to a first embodiment of the present invention.

Here, the feature of the present invention is the transmission signal stop control portion surrounded by a dashed line. That is,
Data from the outside is separated into each low-speed line _l1 and input to the multiplex line concentrator 1. Multiplexed data from the multiplex concentrator 1 is connected to modem devices 2 ₁ and 2 ₂ via high-speed lines l ₂₁ and l ₂₂ , respectively. Modulated signals from the modulation and demodulation devices 2 ₁ and 2 ₂ are connected to the modulation and demodulation devices 3 ₁ and 3 ₂ via relay lines l ₃₁ and l ₃₂ . The data demodulated from the modem devices 3 ₁ and 3 ₂ is transferred to the high-speed line l ₄₁ ,
l ₄₂ to the multiplex concentrator 4. The data is separated from the multiple line concentrator 4 into each low-speed line _l5 and sent to the outside. Further, data input from the outside to the multiplex line concentrator 4 via the low-speed line _l5 is sent to the outside via the low-speed line _l1 in the same manner as described above.

If a fault such as line disconnection occurs in the trunk lines _l71 and _l72 , the modulation/demodulators ₂₁ and ₂₂ detect the fault and detect a carrier indicating to the multiplex concentrator 1 that the carrier is being received. Turn off signals S ₁₁ and S ₁₂
and notify you. The multiplex concentrator 1 generates fallback control signals using fallback signal generation units _D11 and _D12 .
Creates S ₂₁ and S ₂₂ as well as transmission stop signal creation section
D ₃₁ and D ₃₂ create and output a control signal to stop the transmission signal. As a result, fallback control signals S ₂₁ , S ₂₂ are transmitted from the multiplex concentrator 1 to the modem 2 ₁ ,
2 ₂ , and the modems 2 ₁ and 2 ₂ fallback the speed. At the same time, a control signal for stopping the transmission signal is sent from the multiplex concentrator 1 to the modem 2 ₁ ,
2 ₂ , and the modem devices 2 ₁ and 2 ₂ stop outputting the modulated signals.

The modem devices 3 ₁ and 3 ₂ on the other side are trunk lines l ₃₁ and l ₃₂
detects that the signal has stopped, and the modulator/demodulator 3 ₁ ,
3 ₂ turns off the carrier detection signals S ₄₁ and S ₄₂ ,
The multiple line concentrator 4 is notified. Fallback control signals S ₅₁ and S ₅₂ are sent from the multiplex concentrator 4 to the modem 3
₁ and ₃₂ , and the modem devices ₃₁ and ₃₂ perform speed fallback.

The operation of the fallback control device having such a configuration will be explained. In the figure, trunk line l ₇₁ ,
l ₇₂ , when a failure such as line disconnection occurs, the modems 2 ₁ and 2 ₂ turn off the carrier detection signals S ₁₁ and S ₁₂ to the multiplex concentrator 1, and
Notify of deterioration of l ₇₁ and l ₇₂ . As a result, the multiplex concentrator 1 inputs the carrier detection signals S ₁₁ and S ₁₂ to the fallback signal generators D ₁₁ and D ₁₂ . The fallback signal generator is normally “Low”, and when the carrier detection signals S ₁₁ and S ₁₂ become “Off”,
It becomes "High" and outputs fallback control signals S ₂₁ and S ₂₂ to the modulation and demodulation devices 2 ₁ and 2 ₂ to roll back the speeds of the modulation and demodulation signals 2 ₁ and 2 ₂ . At the same time, the outputs of the fallback signal generators D ₁₁ and D ₁₂ are input to the transmission stop signal generators D ₃₁ and D ₃₂ .
The transmission stop signal generation units D ₃₁ and D ₃₂ are normally “Low”, and when the outputs of the fallback signal generation units D ₁₁ and D ₁₂ become “High”, they become “High” and are transmitted from the multiplex concentrator 1 to the modulation/demodulation equipment 2 ₁ , 2 ₂ is the trunk line l ₃₁ , l ₃₂
Control signals S ₃₁ , S ₃₂ to stop the transmission signals output to
Output. The modem and demodulators 2 ₁ and 2 ₂ have their speeds rolled back by the above-mentioned control signal from the multiplex concentrator 1, and stop the signals that were being output to the trunk lines l ₃₁ and l ₃₂ . The modem/demodulators 3 ₁ , 3 ₂ on the other side detect that the signals of the trunk lines l ₃₁ , l ₃₂ have stopped, and send the carrier detection (CD) signals S ₄₁ , S ₄₂ to the multiplex line concentrator 4 to "off." ” to notify of relay line deterioration. The multiplex concentrator 4 thereby transmits the modem 3 ₁ ,
_3.sub.32 , fallback control signals _S51 , _S52 are output to the modulator/demodulators 3.sub.1, 3.sub.2, thereby causing the speeds of the modulation/demodulation devices _3.sub.1 , _3.sub.2 to fall back. As a result, the multiplex concentrator 1, the modem 2 ₁ , 2 ₂ , the multiplex concentrator 4 and the modem 3
All speeds of ₁ and 3 ₂ fall back.

〔Effect of the invention〕

As explained above, in the present invention, after a multiplex concentrator receives relay line degradation from a modem, the modem outputs a fallback control signal to the modem and a control signal for the modem to stop transmitting data to the relay line. However, by automatically falling back to the other party's modulation/demodulation equipment, the fallback processing procedure is simple and the time required to complete the fallback can be shortened, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a fallback control device according to an embodiment of the present invention. FIG. 2 is a block diagram of a conventional fallback control device. 1, 4...Multiple line concentrator, 2, 3...Modulator/demodulator, _l1 , _l5 ...Low speed line, _l21 , _l22 , _l41 , _l42 , _l61 ,
l ₆₂ , l ₈₁ , l ₈₂ ... high-speed line, l ₃₁ , l ₃₂ , l ₇₁ , l ₇₂ ...
Relay line, S ₁₁ , S ₁₂ , S ₄₁ , S ₄₂ ... carrier detection signal, S ₂₁ , S ₂₂ , S ₅₁ , S ₅₂ ... fallback control signal, S ₃₁ , S ₃₂ ... control signal, D ₁₁ , _D12 ...Fallback signal generation section, _D31 , _D32 ...Transmission stop signal generation section.

Claims (1)

[Claims] 1. A pair of multiplex line concentrators facing each other and accommodating a plurality of low-speed lines, a modem and a modem connected to each of the pair of multiplex line concentrators, and a relay line connecting the modem and the modem. The modem includes means for detecting line deterioration of a relay line on the input side of the modem, and means for notifying the multiple line concentrator of the detected line deterioration, and the modem corresponds to the multiple line concentrator. A relay line for data communication, including means for outputting a fallback control signal in response to a notification of line deterioration from a modulation/demodulation device, and further comprising means for inputting the fallback control signal from a corresponding multiplex concentrator to the modulation/demodulation device for fallback. A fallback control system, characterized in that the multiplex concentrator is provided with means for outputting a control signal for stopping transmission data to a corresponding modulation/demodulation device upon notification of the line deterioration.