JP3406136B2 - Digital line switching device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital line switching device for accommodating a plurality of digital lines, and when a fault occurs in the currently used accommodation line, the digital line switching device is switched to the accommodation line having no trouble.

[0002]

2. Description of the Related Art Conventionally, as such a digital line switching device, an integrated service digital network (hereinafter referred to simply as ISD
It is known that a line (referred to as N) and an analog dedicated line are accommodated and the ISDN line and the analog dedicated line are switched and connected.

In the digital line switching device, a modem is arranged as a peripheral device for connecting to the analog dedicated line. For example, when a line failure occurs in the analog dedicated line which is currently communicating, the modem is used. It is possible to detect a failure of the analog leased line and switch and connect the faulty analog leased line to the ISDN line having no fault.

However, the digital line switching device requires a modem as a peripheral device for accommodating an analog dedicated line and connecting to the analog dedicated line, so that the line connecting section cannot be integrated. Things happened.

[0005] Therefore, in order to overcome such a situation, JP-4 - digital line switching apparatus as shown in 247725 JP is considered.

As the digital line switching device, a plurality of high-speed digital leased lines are accommodated, and when a fault occurs in the high-speed digital leased line currently in use, the connection is switched to a spare high-speed digital leased line without the fault. To do.

As the digital line switching device,
When detecting a fault in the high-speed digital leased line, it is general to use layer 1 monitoring which is a protocol of the high-speed digital leased line.

According to the digital line switching device, since the high-speed digital leased line is accommodated instead of the analog leased line, a peripheral device connected to the analog leased line is not required, and the line connection unit is integrated as a matter of course. In addition, the communication speed can be increased.

[0009]

However, according to the above-mentioned conventional digital line switching device, the number of contract lines of the high-speed digital leased line must be increased, and the contract line cost increases. There was a problem.

Further, according to the digital line switching device, communication between the digital line switching device 100 and the partner side digital line switching device 100A connected and arranged at the end of the high-speed digital leased line 3 as shown in FIG. During data communication between the terminals 110 and 110A, for example, the other party's digital line switching device 100A and the high-speed digital leased line 3 were normally connected, and the digital line switching device 100 and the high-speed digital leased line 3 were disconnected. In this case, the partner side digital line switching device 100A side normally detects the layer 1 and determines that normal data communication is possible, whereas the digital line switching device 10
The 0 side detects a layer 1 fault and determines that communication is impossible.

That is, the digital line switching device 100
According to the above, according to the layer 1 monitoring, the line state between the digital line switching device 100 and the high-speed digital leased line 3,
In other words, the line failure can be detected, but it cannot be detected until the data channel such as the line state between the partner side digital line switching device 100A and the high-speed digital leased line 3 is communicable. There was a problem.

The present invention has been made in view of the above-mentioned first problem. A first object of the present invention is to realize a digital communication system which has a high communication speed and can significantly reduce the contract line cost. It is to provide a line switching device.

The present invention has been made in view of the above-mentioned second problem. A second object of the present invention is to provide a high-speed digital leased line even if a line failure occurs.
An object of the present invention is to provide a digital line switching device capable of surely detecting whether or not a data channel on the high-speed digital leased line can communicate.

[0014]

Digital line switching unit of the first aspect of the present invention in order to achieve the first object, according order to achieve the above, a dedicated line connecting means for connecting the leased line, IS
And ISDN line connection means for connecting the DN line, the switching selection means for switching selection of one of the private line connection means and the ISDN line connection means, the line fault detecting means for detecting a line failure in said leased line usually with to select the private line connection means via said switching selection means, when the line fault is detected in the inner leased lines in the line fault detecting means, the dedicated through the switching selection means Control means for switching and selecting from the line connection means to the ISDN line connection means, and at least two data lines of the dedicated line.
At least first and second tests via the data channel
A pattern transmission / reception means for transmitting / receiving a pattern.
A digital circuit switching device, wherein the control means is
Via one of the data channels of the
From the transmission / reception means to the other party's digital line switching device.
Send the first test pattern and send the pattern
The receiving means uses the other data channel of the dedicated line.
Via the other party's digital line switching device,
When the test pattern of 1 is received, the predetermined timer value
After the passage of the
Send the test pattern 2 and send the pattern
Through the other data channel of the leased line
The second digital line switching device from the other party.
When the test pattern is received, on the dedicated line
The feature is that it is determined that data communication is possible .

The dedicated line connecting means is a dedicated line interface for controlling connection with the high-speed digital dedicated line, and the ISDN line connecting means is an ISDN line interface for controlling connection with the ISDN line. The detection means detects a line fault in the high-speed digital leased line at layer 1.

Therefore, according to the digital line switching device of the first aspect of the invention, the data communication between the communication terminals is normally performed by the high-speed digital leased line, and the line fault is detected in the high-speed digital leased line. Then, since the high-speed digital leased line is switched and connected to the ISDN line, that is, the contract line cost of the ISDN line is lower than that of the high-speed digital leased line accommodated in the line switching device, the contract is concerned. The line cost can be significantly reduced.

Further, the digital line switching unit of the second invention in the present invention, in addition to the configuration of the first invention, the
The predetermined timer value is used when the data arrival delay of the dedicated line
It is characterized in that it is not less than the interval .

Therefore, according to the digital line switching device of the second aspect of the invention, the high-speed digital line switching device connected to the end of the high-speed digital leased line and the high-speed digital line switching device are connected to each other. Since the test patterns are transmitted and received to and from each other via the two data channels of the dedicated line, for example, the test pattern obtained via the data channel can be received by the digital line switching device and the partner side digital line switching device. If it is possible, the data channel can be communicated, and if the test pattern obtained via the data channel cannot be received, it can be determined that the data channel cannot be communicated. Even if a line failure occurs in the high-speed digital leased line,
It is possible to reliably detect whether or not the data channel on the high-speed digital leased line is communicable,
It can provide users with reliable high-speed digital leased line data communication.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the digital line switching device of the present invention will be described below. FIG. 1 is a block diagram showing a connection configuration of the digital line switching device.

In FIG. 1, the high-speed digital leased line 3 and the IS
A DN line 4, a digital line switching device (hereinafter, simply referred to as a line switching device) 1 on one side of the ends of these lines, and a partner line which is a partner of the line switching device 1 on the other side. A switching device 1A is connected, and a communication terminal 2 is connected to the line switching device 1 and the partner line switching device 1
The partner communication terminal 2A is connected to A.

An outline of the line switching device 1 is that data communication is performed through a communication route 5 via a high-speed digital leased line 3 during normal data communication between the communication terminal 2 and the partner communication terminal 2A. However, if a line failure occurs between the line switching device 1, the high-speed digital leased line 3 and the partner line switching device 1A during the data communication, the ISD from the high-speed digital leased line 3 is connected.
By performing data communication through the communication route 6 that is switched and connected to the N line 4, the communication between the communication terminal 2 and the communication terminal 2A is guaranteed.

Next, the external structure of the line switching device 1 will be described. 2A and 2B are explanatory views schematically showing the external configuration of the line switching device 1, FIG. 2A is a rear view of the line switching device 1, FIG. 2B is a plan view, and FIG.
FIG. 2C is a front view and FIG. 2D is a side view.

In FIG. 2, the line switching device 1 has a main body case 10 having a box shape, an operation panel 20 is provided on the front surface of the main body case 10, and a rear panel 30 and a power supply are provided on the rear surface of the main body case 10. Is equipped with a power cord 40. Incidentally, the rear panel 30
Includes a communication terminal 2, a high-speed digital leased line 3 and an ISDN.
Connection terminals and the like for connecting to the line 4 are provided.

Next, the operation panel 20 will be described. FIG. 3 is a plan view of the operation panel 20.

In FIG. 3, an operation panel 20 has a function key 21 for activating registration and reading of speed information required for communication on the high-speed digital leased line 3 and ISDN line 4, switching mode setting, and manual switching operation, and the like. High speed digital leased line 3 and ISDN with function key 21
Numeric keypad 22 for setting communication conditions necessary for communication on line 4 and setting the partner line number for communication on ISDN line 4
A liquid crystal display 23 for displaying the setting contents set by the function keys 21 and the numeric keypad 22 and the line status of the line being communicated, and a status display lamp 24 for displaying the line status of the line switching device 1 And have.

As the status display lamp 24, a power supply lamp 24a is displayed when power is being supplied to the line switching device 1 and is displayed when an abnormality occurs in the line switching device 1. The alarm lamp 24b, the signal line status display lamp 24c for displaying the state of the signal line with the communication terminal 2, and the line lamp 24d for indicating the line in communication.
And a layer 1 lamp 24 showing the state of layer 1 of each line
e and.

Next, the rear panel 30 of the line switching device 1 will be described. FIG. 4 is a plan view of the back panel 30.

In FIG. 4, the rear panel 30 is an X.X connected to the communication terminal 2. 21 connector 31 and V.21. 35 connector 32, a modular connector 33 connected to the high-speed digital dedicated line 3, a modular connector 35 connected to the ISDN line 4, an AUX connector 37 for notifying the operating state of the line switching device 1 to the outside, It has a terminating resistance changeover switch 34 for the high-speed digital dedicated line, a terminating resistance changeover switch 36 for the ISDN line, and a power switch 41 for turning on / off the power supply to the line switching device 1. The X. 21 connector 3
1 and V.I. The 35 connector 32 can be selected by setting from the operation panel 20.

The termination resistance changeover switch 34 can be terminated or unterminated with a resistance value of 100 ohms with respect to the high-speed digital dedicated line 3. Similarly, the termination resistance changeover switch 36 can also be terminated or unterminated with a resistance value of 100 ohms with respect to the ISDN line 4.

Next, the internal configuration of the line switching device 1 will be described. FIG. 5 is a block diagram showing a schematic configuration of the inside of the line switching device 1.

In FIG. 5, the line switching device 1 has a communication terminal interface (DTE interface) 102 for connecting to a communication terminal (DTE) 2 and a high-speed digital leased line interface 110 for connecting to a high-speed digital leased line 3. And IS for connecting to the ISDN line 4
The DN line interface 120 and the line selection switch 103 for selecting the line connected to the communication terminal 2
And a control unit 101 that controls the entire line switching device 1 via a control bus 104. The line switch 103 is connected to the communication terminal 1 in response to a switching control signal from the control unit 101, that is, I
The SDN line 4 or the high-speed digital leased line 3 is switched and connected.

High-speed digital leased line interface 1
Reference numeral 10 denotes a line control unit 112 that controls the high-speed digital leased line 3, a speed matching unit 111 that matches the communication speed with the communication terminal 2, and whether or not the data channel of the high-speed digital leased line 3 is normal. It has a communication port 113 for performing a test.

The ISDN line interface 120
Is a line control unit 122 that controls the ISDN line 4.
And a speed matching unit 121 that matches the communication speed with the communication terminal 2.

Next, an outline of the operation when the line switching device 1 is online will be described. FIG. 9 is a state transition diagram for explaining the operating state of the line switching device 1.

In FIG. 9, the line switching device 1 supplies power to the device main body 1 and waits for a state in which the high-speed digital leased line 3 is in the waiting state for establishing the leased line synchronization and there is no incoming call from the ISDN line 4. State (step S100)
Then, when the synchronization of the high-speed digital leased line 3 is established, the high-speed digital leased line 3 transits to the communication state (step S200).

The standby state (step S100)
When there is an incoming call from ISDN line 4,
A transition is made to the DN line incoming state (step S300).

In the communication state of the high-speed digital leased line 3 (step S200), when disconnection of layer 1 is detected in the high-speed digital leased line 3, the high-speed digital leased line 3 is switched to the ISDN line 4 for connection. When a transition is made to the ISDN line calling state (step S400) and an incoming call to the ISDN line 4 is detected, ISD
A transition is made to the N line incoming call state (step S300).

The ISDN line calling state (step S4)
00) and ISDN line incoming state (step S300)
When the synchronization of the ISDN line 4 is established, the state of the ISDN line 4 is changed to the communication state (step S500).

In the communication state of the ISDN line 4 (step S500), the high speed digital leased line 3 is
When the synchronization of is established, the communication state of the high-speed digital leased line 3 is changed (step S200).

If the ISDN line 4 is disconnected in the communication state of the ISDN line 4 (step S500) and the synchronization of the high-speed digital leased line 3 is not established, the standby state (step S100)
Transition to.

Next, the switching operation of the line switching device 1 will be described. FIG. 6 is a flowchart showing the processing operation of the control unit 101 in the channel test processing of the line switching device 1. FIG. 7 is a sequence diagram when the channel test process is normal.

The channel test processing means that the line switching connection devices 1 and 1A are connected and arranged at the ends of the high-speed digital leased line 3, and the high-speed digital signal is connected between the line connection device 1 and the partner line connection device 1A. This is a process of determining whether or not data communication in the data channel of the dedicated line 3 is possible.

Here, only the processing operation in the control unit 101 on the side of the line switching apparatus 1 will be described, but it is assumed that the same processing operation is performed in the control unit 101 on the side of the partner line switching apparatus 1A.

In FIG. 6, the control unit 101 transfers the first test pattern P1 from the communication port 113 of the high speed digital leased line interface 110 through the high speed digital leased line 3 to the partner side line switching device as shown in FIG. 1
It is sent to A (step S1). Next, it is determined whether or not the first test pattern P1 is received from the partner line switching device 1A (step S2).

If the first test pattern P1 from the partner line switching device 1 is received, the first timer (T1) is started (step S3) and it is determined whether or not the first timer has timed out. Judge (step S
4). In the first timer, the first test pattern P1 sent in step S1 is the line switching device 1 on the partner side.
This is a timer for ensuring that A is surely received.

If the first timer times out in step S4, the transmission of the first test pattern P1 in step S1 is stopped (step S5), and the second test pattern P2 is transmitted from the communication port 113 in the high speed mode. The data is sent to the partner line switching device 1A via the digital leased line 3 (step S6). Second timer (T2)
Is started (step S7), and it is determined whether or not the second timer has timed out (step S8).

If the second timer has not timed out, it is determined whether or not the second test pattern P2 sent from the partner side line switching device 1A has been received (step S9). The second timer is a timer for ensuring that the second test pattern P2 transmitted from the partner line switching device 1A is reliably received.

In step S9, the second test pattern P2
If the third timer (T3) is received, the third timer (T3) is started (step S10), and it is determined whether or not the third timer has timed up (step S11). The third timer is a timer for ensuring that the second test pattern P2 sent in step S6 is reliably received by the partner line switching device 1A.

If the third timer times out in step S11, the transmission of the second test pattern P2 transmitted in step S6 is stopped (step S1).
2), the third test pattern P from the communication port 113
3 is sent to the partner line switching device 1A via the high-speed digital leased line 3 (step S13). Next is the fourth
The timer (T4) is activated (step S14), and it is determined whether or not the fourth timer has timed up (step S15).

If the fourth timer has not timed out, the third timer sent from the partner line switching device 1A is sent.
It is determined whether the test pattern P3 has been received (step S16). The fourth timer is a timer for ensuring that the third test pattern P3 transmitted from the partner line switching device 1A is reliably received.

If the third test pattern P3 is received from the partner line switching device 1A in step S16, the fifth timer (T5) is started (step S1).
7), it is determined whether or not the fifth timer has timed out (step S18).

If the fifth timer has timed out, the sending of the third test pattern P3 sent in step S13 is stopped (step S19), and the sixth timer (T6) is started (step S20). . Since the sixth timer may still send the third test pattern P3 from the partner line switching device side 1A when starting the data communication in the communication terminal after the completion of the data channel test. , Third to the communication terminal
This is a timer for preventing the test pattern P3 from being transmitted.

After the processing of step S16, it is determined whether or not the first test pattern P1 from the partner line switching apparatus 1A has been received (step S21). Incidentally, step S
If the switching operation of the other party's line switching device 1A is not possible yet, the processing operation of 21 is performed by the other party's line switching device 1A.
This is because the first test pattern P1 may be sent from the A side.

If the first test pattern P1 has not been received, it is determined whether the sixth timer has timed out (step S22). If the sixth timer has timed out, the data communication between the communication terminals 2 and 2A is switched (step S23), and the processing operation related to the channel test processing is ended.

If the second timer times out in step S8, or the fourth timer times out in step S15, or the first test pattern P1 is received in step S21. If there is, the process proceeds to step S1.

If the second test pattern P2 is not received in step S9, the process proceeds to step S8. In step S16, the third test pattern P3
If it is not received, the process proceeds to step S15.
If the sixth timer has not timed out in step S22, the process proceeds to step S21.

The first, second, third, fourth, fifth and sixth timers may be set to timer values equal to or longer than the data arrival delay time of the high speed digital dedicated line.

FIG. 7 is a sequence diagram showing when the data channel between the line switching device 1 and the partner side line switching device 1A is normal, while FIG. 8 is a sequence diagram showing when the data channel is abnormal. is there.

In the sequence diagram shown in FIG. 8, one side is disconnected in the high-speed digital leased line 3 between the line switching device 1 and the partner line switching device 1A, that is, from the line switching device 1 to the partner line switching device 1A. Is disconnected, and the data channel from the partner side line switching device 1A to the line switching device 1 is normally connected.

When the channel test process is executed during this one-side disconnection, the first test pattern P1 sent from the line switching device 1 does not reach the partner line switching device 1A, so the partner line switching device 1A is concerned. The first test pattern P1 is continuously sent to the line switching device 1.

First from the other party line switching device 1A side
Since the test pattern P1 reaches the line switching device 1, when the line switching device 1 times up the first timer for guaranteeing reception in the first test pattern P1 from the partner line switching device 1A side, The transmission of the second test pattern P2 is started.

The line switching apparatus 1 is waiting for reception of the second test pattern P2 sent from the partner line switching apparatus 1A, but the partner line switching apparatus 1A sends the first test pattern P1. Therefore, when the second timer of the line switching device 1 times out, the line switching device 1 returns to sending the first test pattern P1.

By such a process, it is possible to detect the one-side disconnection in the high-speed digital dedicated line 3.

Therefore, according to the digital line switching apparatus 1, normally, the high speed digital leased line 3 is used to perform data communication between the communication terminals 2 and 2A, and the line fault is detected in the high speed digital leased line 3. Then, since the high-speed digital leased line 3 is switched and connected to the ISDN line 4, the contracted line cost of the ISDN line 4 is higher than that of the high-speed digital leased line 3 accommodated in the line switching device 1. Since it is cheap, the contract line cost can be significantly reduced.

Further, according to the digital line switching device 1, the high-speed digital dedicated line is connected between the digital line switching device 1 and the partner side digital line switching device 1A connected and arranged at the end of the high-speed digital dedicated line 3. Since the test patterns are transmitted / received to / from each other via the two data channels of the line 3, for example, the test patterns obtained via the data channels are mutually exchanged between the digital line switching device 1 and the partner side digital line switching device 1A. If the test pattern obtained via the data channel cannot be received, it is determined that the data channel cannot be communicated. Therefore, even if a line failure occurs in the high-speed digital leased line 3, Up whether the data channels in speed digital leased line 3 can communicate can be reliably detected, by force it can provide communications in high-speed digital leased lines reliable user.

[0066]

According to the digital line switching device of the present invention configured as described above, the data communication between the communication terminals is normally performed by the high speed digital leased line,
When a line fault is detected in the high-speed digital leased line, the high-speed digital leased line is switched to the ISDN line, that is, the ISDN line is more suitable than the high-speed digital leased line accommodated in the line switching device. Since the contract line cost is low, the contract line cost can be significantly reduced.

According to the digital line switching device, two high-speed digital dedicated lines are connected between the digital line switching device and the partner digital line switching device connected and arranged at the end of the high-speed digital dedicated line. Since the test patterns are transmitted / received to / from each other via the data channel of, for example, when the test pattern obtained via the data channel can be received by the digital line switching device and the partner side digital line switching device. If the data channel is communicable and the test pattern obtained via the data channel cannot be received, it can be determined that the data channel is incommunicable. Even if a line failure occurs, the data Tunnels can also be reliably detected until whether communication is possible, by force becomes possible to communicate in a reliable high-speed digital dedicated line.

[Brief description of drawings]

FIG. 1 is a block diagram showing a connection configuration in a digital line switching device of the present invention.

FIG. 2 is an explanatory view schematically showing an external configuration of a digital line switching device of the present invention. (A) Rear view of the line switching device (b) Plan view of the line switching device (c) Front view of the line switching device (d) Side view of the line switching device

FIG. 3 is a plan view showing an operation panel of the digital line switching device.

FIG. 4 is a plan view showing a rear panel of the digital line switching device.

FIG. 5 is a block diagram showing a schematic configuration inside the digital line switching device.

FIG. 6 is a flowchart showing a processing operation of a control unit in a channel test processing of the digital line switching device.

FIG. 7 is a sequence diagram showing a normal data channel between the line switching device and the partner line switching device during the channel test process.

FIG. 8 is a sequence diagram showing a case where the data channel between the line switching device and the partner line switching device is abnormal during the channel test process.

FIG. 9 is a state transition diagram schematically showing an operating state of a line switching connection in the line switching device.

FIG. 10 is a block diagram showing a connection configuration in a conventional digital line switching device.

[Explanation of Codes] 1 line switching device (digital line switching device) 1A partner line switching device (party digital line switching device) 3 high-speed digital leased line 4 ISDN line 101 control unit (control means) 103 line switching switch (switching) Selection means) 110 High-speed digital leased line interface (dedicated line connection means) 113 Communication port (pattern transmission / reception means, line failure detection means) 120 ISDN line interface (ISDN line connection means)

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Claims (2)

(57) [Claims] And 1. A dedicated line connection means for connecting the leased line, the ISDN line connection means for connecting an ISDN line, a switching selection means for switching selection of one of the private line connection means and the ISDN line connection means , a line fault detection means for detecting a line failure in said leased line, usually with to select the private line connection means via said switching selection means, said at the line fault detecting means dedicated
Via the line fault is detected in the use time line, and control means for switching selection to ISDN line connection means from the dedicated line connection means via said switching selection means, at least two data channels of said dedicated line
To transmit and receive at least the first and second test patterns
Digital line switching device having pattern transmitting / receiving means
The control means is a data channel of one of the leased lines.
From the pattern transmission / reception means via the
Send the first test pattern to the digital line switching device
The pattern transmission / reception means other than the dedicated line.
Via the other data channel
Received the first test pattern from the line switching device
In this case, the other party's digital
The second test pattern to the line switching device.
The pattern transmitting / receiving means is the other of the dedicated lines.
The other party's digital line is disconnected via the data channel.
When the second test pattern is received from the replacement device,
In this case, the digital line switching device is characterized by determining that data communication is possible on the dedicated line . 2. The predetermined timer value is the leased line
2. The digital line switching device according to claim 1 , wherein the data arrival delay time is equal to or more than the data arrival delay time .