JPH0377466A - Backup system for private line in digital multiplexer - Google Patents

Abstract

PURPOSE:To improve the reliability of the communication system by using a switching means to switch of line from a private line into an exchange line automatically when a fault of the private line is detected. CONSTITUTION:Digital multiplexers 11,12 are provided with interfaces 13, 14, 16 and a changeover switch 15 and a private line interface 13 has a function as a fault detection means detecting a fault of the private line 18. When a fault of the private line is detected, the changeover switch 15 changes over the private line 18 into an exchange line 19 automatically to apply backup communication by the exchange line. Thus, the private line with a high cost is backed up with a low cost exchange line and the reliability of the communication system is improved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention provides communication using two types of lines: dedicated lines such as high-speed digital leased lines, and switched lines such as integrated service digital switching networks (hereinafter referred to as 15DN). The present invention relates to a method for backing up a dedicated line in a communication system consisting of a digital multiplexer connected to a network.

[Prior Art] FIG. 4 is an explanatory diagram showing a conventional switching method between a dedicated line and a switched line between terminal devices, as disclosed in, for example, Japanese Patent Application Laid-Open No. 63-59625.

In the figure, 1 to 3 are terminal devices, 4 to 6 are subscriber lines,
Subscriber lines 4 and 6 are also dedicated lines.

Subscriber lines 4 and 5 each have a communication channel 4a.

5a and call control channels 4b and 5b, and the subscriber line (dedicated port vA) 6 is a transmission path for only communication channels. Also, 7 is subscriber line 4 and subscriber line 5.
, 6 is a communication mode switching device 8, which is a bucket switch (or circuit switch) installed in the subscriber line 5.

Next, the operation will be explained. Normally, the terminal devices 1 and 3 perform one-to-one dedicated line communication via the communication channel 4a and the dedicated @ line 6.

When the terminal device 1 attempts to communicate with the terminal device 2 (communication via a switched line), the terminal device 11 first notifies the terminal device 3 of a switching notice via the communication channel 4a and the dedicated line 6. Next, install the terminal! 1 sends an exchange mode switching request signal to the communication mode switching device [7 via the call control channel 4b. As a result, the communication mode switching device 7 switches the path to the communication channel between the exchange 8 and the terminal device 1, and then sends a switching completion signal to the terminal device 1 via the call control channel 4b.

When the terminal device lt1 receives the switching completion signal, the terminal device lt1 switches the call control channel 4b in the case of circuit switching mode communication.

At step 5b, a predetermined call control sequence is performed to set up a call, and then a communication sequence with the terminal device [2 is started.

[Problem to be solved by the invention] In the conventional switching method between a leased line and a switched line, switching was not performed only by call control from the terminal device 1, and the switched line could not be used as a backup for the leased line. .

This invention was made to solve the above-mentioned problems, and improves reliability by making it possible to communicate using a switched line when a dedicated line fails.

The purpose of this paper is to obtain a backup method for dedicated lines in digital multiplexing equipment.

[Means for Solving the Problems] A dedicated line backup method in a digital multiplexing device according to the present invention is configured by interconnecting a plurality of digital multiplexing devices using two types of lines: a dedicated line and a switched line. In the communication system, there is a fault detection means for detecting a fault in the dedicated line, and communication between the digital multiplexers is performed by switching between the dedicated @ line and the switched line according to the detection result by the fault detection means. A switching means is provided in each digital multiplexing device, and when the fault detection means detects a fault in the dedicated line, the switching means switches to the switched line side, and the switched line switches the dedicated line to the switched line side. This is to back up the information.

[Function] In the dedicated line backup method in the digital multiplexing device of the present invention, when a fault in the dedicated line is detected by the fault detection means, the switching means automatically switches from the dedicated line to the switched line side. Then, backup communication is performed using switched lines.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 11.12 is a digital multiplexing device;
13 is leased line interface, 14 is l5DN (switched line) interface, 15 is interface 1
3.14 (that is, a dedicated line).

16 is a terminal interface, 17 is a terminal device, and 18 is a switch for communicating between digital multiplexers 11 and 12 by switching to one of the digital multiplexers 11 and 12 (switched line); The connecting high-speed digital dedicated line (dedicated IIA), 19 is the 15DN network (switched line) that connects the digital multiplexing devices 11 and 12, and each digital multiplexing bag! 11.12 are all configured with interfaces 13, 14.16 and changeover switches 15, and are connected to a plurality of terminal devices 17.

In addition, the dedicated line interface 13 is a dedicated wA18
It has a function as a fault detection means for detecting faults. Fault detection is performed as follows. That is, the dedicated @ line interface 13 on the transmitting side transmits a synchronization pattern as communication data in order to achieve multi-frame synchronization, while the dedicated line interface 13 on the receiving side,
This synchronization pattern is detected and multi-frame synchronization is performed, but as long as this synchronization pattern can be received normally, the leased line 18 is judged to be normal, and if synchronization cannot be achieved, that is, the synchronization pattern cannot be received. It is determined that a fault has occurred in the dedicated line 18.

When a fault in the dedicated line 18 is detected by the interface 13 during communication using the dedicated line 18, the changeover switch 15 automatically switches from the dedicated line 18 side to the L5DN network 19 side, and when the fault is recovered, the L5DN network 19
The system automatically switches from the private line 18 side to the dedicated line 18 side.

Next, the operation of this embodiment will be explained.

By monitoring mutually transmitted synchronization patterns on the dedicated line interface 13, when a failure in the dedicated 1s18 is detected, the 15DN interface 14 is immediately
to set up a call to the l5DN network 19, and connect the l5DN in the other party's digital multiplexer 11 or 12.
When a communication path is established with the interface 14, the selector switch 15 is switched from the leased line interface 13 side to the 15DN interface 14 side, and the path within the digital multiplexer 11 and 12 is set. In this step, a communication path is established between the 15DPT interface 14 and the terminal interface 16. on the other hand,
On the other side, rsDN interface 14 has l5DNl.
There is an incoming call from 119, and from this, the calling side can know that a failure has been detected and backup operation has started, and even if the other party has not detected a failure, both parties can
9 backup communication becomes possible.

As described above, according to the method of this embodiment, communication can be performed using the l5DN[19] when the dedicated line 18 fails, so the expensive dedicated line 18 can be backed up by the low cost l5DN Ifi19, and the reliability of the communication system can be improved. can be increased.

In the above embodiment, the changeover switch 15 is provided between the terminal interface 16, the dedicated line interface 13, and the l5DN interface 14.
As shown in the figure, a terminal interface 16 and a leased line interface 13 are connected (configuration similar to a conventional multiplexing device with only leased lines), and a changeover switch 15 is installed between the leased line operator 8 and the leased line interface 13. Furthermore, an I5DN interface 14 is provided from the other side of the changeover switch 15, and an I5DN network 19 is connected thereto. At this time, a leased line signal (CM
I code) by adding a circuit that converts it to an SDN signal (AM■ code).

The same effects as in the above embodiment are achieved.

Further, as shown in FIG. 3, in a multi-link digital multiplexer 21 accommodating a plurality of leased lines 18, a time slot conversion circuit 20 is provided as a switching means, and this conversion circuit 20 allows the leased line interface 13
By switching the path between the L5DN interface 14 and the terminal interface 16 to the path between the SDN interface 14 and the terminal interface 16, backup of the leased line 18 can be realized. It is possible to back up with .

[Effects of the Invention] As described above, according to the present invention, when a fault in the dedicated line is detected by the fault detection means, the switching means automatically switches from the dedicated line to the switched line side, thereby providing backup by the switched line. Since I configured it to be able to communicate,
In addition to being able to back up expensive dedicated lines with low-cost switched lines, it also has the effect of improving the reliability of communication systems.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a communication system to which a dedicated line backup method is applied in a digital multiplexing device according to an embodiment of the present invention, and FIGS. FIG. 4 is an explanatory diagram showing a conventional switching method between a dedicated line and a switched line between terminal devices. In the figure, 11.12-digital multiplexer, 13
- Dedicated line interface (fault detection means), 15-
Changeover switch (switching means), 18-high-speed digital dedicated line (dedicated line), 19-ISDN network (switched line), 20
- time slot conversion circuit (switching means); 21 - multi-link digital multiplexing device; In addition. In the figure, the same symbols are the same. Or a considerable portion is shown.

Claims (1)

[Scope of Claims] A communication system comprising a plurality of digital multiplexing devices interconnected by two types of lines, a dedicated line and a switched line, comprising: a fault detection means for detecting a fault in the dedicated line; and a fault detection means for detecting a fault in the dedicated line; Each of the digital multiplexing apparatuses is provided with a switching means for switching between the dedicated line and the switched line in accordance with the detection result of the detection means to perform communication between the digital multiplexing apparatuses, Digital multiplexing characterized in that when a fault in the dedicated line is detected by the fault detection means, the switching means switches to the switched line side, and the switched line backs up the dedicated line. Backup method for dedicated lines in equipment.