JPH09238118A - Line changeover device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain line changeover by providing a function converting a signal transmission speed into a predetermined unified speed from a substantial speed and restoring the speed to the substantial speed so as to use a time switch. SOLUTION: In the case of sending a signal by a terminal equipment 10(X) (X=1, 2,..., N), a serial signal consisting of a transmission data signal SD and a transmission request signal RS is outputted. The serial signal is given to a DTE channel section 10(X), in which the transmission speed is converted from a substantial speed into a predetermined unified speed and fed to a DCE channel section 220(X) via a line changeover section 230. When an active line 40(Z) is faulty, the signal is fed to a standby DCE channel section 220(N+1). The supplied serial signal is restored to the substantial speed from the unified speed and the serial signal consisting of the SD and RS is decoded and sent to the active line 40(X) or the standby line 40(N+1) via an active line terminator 30(X) or a standby line terminator 30(N+1). This is similar to receive the signal from the line 40(X) or the line 40(N+1).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is shared by a plurality of terminal devices having different signal transmission rates, and when the working line of each terminal device becomes unusable due to a line failure or a device failure, the terminal device The present invention relates to a line switching device that switches a used line from a working line to a protection line.

[0002]

2. Description of the Related Art Generally, in a data transmission system using a dedicated line, a backup line is provided in addition to the working line.
When the working line cannot be used due to a line failure or a device failure, the working line is switched from the working line to the protection line.

By the way, in the above-mentioned data transmission system, a plurality of terminal devices are usually provided as terminal devices. Therefore, when a line switching device is provided in this system, it is desirable to provide a line switching device shared by all terminal devices from the viewpoint of simplification of the circuit configuration.

In the above-mentioned data transmission system, the signal is usually a Japanese Industrial Standard (JIS) X
The signal defined by 5101 is used. This JIS
In the X5101, a plurality of signals having different transmission rates are prepared. Therefore, when there are a plurality of terminal devices, the transmission rates of signals used by the respective terminal devices may differ. Therefore, when configuring a line switching device shared by a plurality of terminal devices, a configuration capable of coping with a plurality of signals having different transmission rates is desired.

In order to meet the above demands, conventionally, a line switching device shared by a plurality of terminal devices has been configured by using a space switch composed of a space dividing element such as a relay.

[0006]

However, in such a configuration, when the number of channels is increased or a complicated switching operation is performed, a large number of space division elements are required, which makes the line switching device complicated. There was a problem of becoming.
Further, this causes a problem that the hardware failure of the line switching device itself cannot be ignored.

[0007]

In order to solve the above problems, the present invention has a function of converting a signal transmission rate from an original rate to a predetermined unified rate, and returning from this rate to the original rate. By providing it, the line is switched by using the time switch.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

[One Embodiment] [Structure] FIG. 1 is a block diagram showing the structure of an embodiment of the present invention. It should be noted that FIG. 1 shows the present invention in which N working lines 40 (1) to 40 (N) and one protection line 4 are provided.
A case where the present invention is applied to a line switching device of a data transmission system having 0 (N + 1) is shown as a representative.

The illustrated line switching device 20 includes N data terminal devices (DTE) 10 (1) to 10 (N) and (N).
+1) line terminators (DCE) 30 (1) to 30
It is provided between (N + 1). Here, the line terminators 30 (1) to 30 (N) are the working lines 30 (1), respectively.
To 30 (N), and the line terminating device 30 (N + 1)
Are connected to the protection line 40 (N + 1).

The line switching device 20 includes N DTE channel units 210 (1), 210 (2), ..., 210 (N).
And (N + 1) DCE channel units 220 (1), 2
20 (2), ..., 220 (N + 1) and the line switching unit 2
30 and 30.

Here, each DTE channel unit 210 (x)
(X = 1, 2, ..., N) is provided for each terminal device 10 (x), and the speed of the transmission signal output from the corresponding terminal device 10 (x) is standardized in advance from the original speed. It has a function of converting to a speed and a function of returning the speed of the reception signal supplied from the line switching unit 230 from the uniform speed to the original speed.

Each DCE channel unit 10 (y) (y = 1,
2, ..., N + 1) are provided for each line terminating device 30 (y), and have a function of returning the transmission rate of the transmission signal supplied from the line switching unit 230 from the uniform rate to the original rate, and the corresponding line termination. It has a function of converting the transmission rate of the reception signal supplied from the device 30 (y) from the original rate to the unified rate.

When a line switching request is generated, the line switching unit 230 has a function of switching the used line from the working line 40 (x) to the protection line 40 (N + 1) by using a time switch.

FIG. 2 is a block diagram showing the configuration of the DTE channel section 210 (x). The illustrated DTE channel unit 210 (x) is a DTE interface circuit 211.
(X), a mapping circuit 212 (x), and a speed matching circuit 213 (x).

Here, the DTE interface circuit 211
(X) has a function of connecting the mapping circuit 212 (x) and the corresponding terminal device 10 (x).

The mapping circuit 212 (x) allocates the transmission signal output from the corresponding terminal device 10 (x) to a predetermined frame, so that the mapping circuit 212 (x) divides the transmission rate by a fraction of an integer.
It has a function of generating a signal having an intermediate speed and a function of obtaining a received signal having an original speed by extracting the received signal from the frame of the signal supplied from the speed matching circuit 213 (x).

The speed matching circuit 213 (x) has a function of converting the transmission speed of the signal supplied from the mapping circuit 212 (x) from an intermediate speed to a predetermined uniform speed, and a signal supplied from the line switching unit 230. It has the function of converting the transmission speed of the standard speed from the uniform speed to the intermediate speed.

FIG. 3 is a block diagram showing the configuration of the DCE channel unit 220 (y). The illustrated DCE channel unit 220 (y) has a speed matching circuit 221, a mapping circuit 222, a null modem circuit 223, and a DCE interface circuit 224.

The speed matching circuit 221 (y), the mapping circuit 222 (y), and the DCE interface circuit 224.
(Y) is the speed matching circuit 213 (x) of the DTE channel unit 210 (x) and the mapping circuit 212, respectively.
Since (x) and the DTE interface circuit 211 (x) have substantially the same functions, detailed description thereof will be omitted here. The null modem circuit 223 (y) is JIS
It has a function of exchanging signals (cross connection) defined by X 5101.

FIG. 4 is a block diagram showing the configuration of the line switching unit 230. The illustrated line switching unit 230 includes a first and second time division demultiplexing / demultiplexing circuits 231, 232, a time switch 233, an operation setting unit 234, and a control unit 235.
And

Here, the first time division demultiplexing circuit 231
Represents the number of time slots (temporal position) of the transmission signals supplied from the DTE channel units 210 (1) to 210 (N), which is the sum (N + 1) of the number N of working lines and the number of protection lines 1 in one multiplexing period. And the function of performing time division multiplexing so that the time division multiplexed signal of the received signal supplied from the time switch 233 is separated for each multiplexed signal, and the corresponding DTE channel units 210 (1) to 210 (N) are provided. Has the function of sorting.

The second time division demultiplexing circuit 232 uses a DC
A function to time-division-multiplex the received signals supplied from the E channel units 220 (1) to 220 (N), and the time switch 23
The time-division multiplexed signal supplied from H. 3 is separated for each multiplexed signal, and the corresponding DCE channel units 220 (1) to 220 (22)
It has a function of allocating to 0 (N).

The time switch 233 replaces the time slot of the time division multiplexed signals output from the first and second time division multiplexing / demultiplexing units 231 and 232, and thereby reserves the used line from the working line 40 (x). Line 40 (N + 1)
It has a function to switch to.

The operation setting unit 234 is a user interface for the user to input a line switching request command when the working line 40 (x) becomes unusable due to a line failure or a device failure. is there.

The control unit 235 has a function of controlling the operation of the time switch 233 based on the line switching command input via the operation setting unit 234.

[Operation] The operation of the above configuration will be described. In the following description, the present invention will be described as the working line 40.
(1) to 40 (N) and the protection line 40 (N + 1),
A case of applying to a line switching device of a data transmission system using a dedicated line will be described as a representative.

In this data transmission system, as described above, generally, a signal specified by JISX 5101 is used as a signal. This signal includes a transmission data signal SD, a reception data signal RD, and a transmission request signal R.
There are S, a transmission enable signal CS, and a reception carry detection signal CD.

First, the operation of the entire line switching device 20 will be described with reference to FIG. This operation is performed by the terminal device 1
The operation when 0 (x) transmits a signal is roughly divided into the operation when it receives a signal.

First, the operation of the line switching device 20 when the terminal device 10 (x) transmits a signal will be described.

In this case, from the terminal device 10 (x), J
A serial signal composed of a transmission data signal SD and a transmission request signal RS defined by IS X 5101 is output. The serial signal is converted by the DTE channel unit 10 (x) from the original transmission speed to a predetermined uniform transmission speed.

If the working line 40 (x) is usable, the serial signal converted from the transmission speed to the unified speed is sent to the working DCE channel unit 220 via the line switching unit 230.
(X). In contrast, the working line 40 (x)
If the line cannot be used due to a line failure or a device failure, the spare DCE channel unit 220 is connected via the line switching unit 230.
(N + 1).

The serial signal supplied to the working DCE channel unit 220 (x) or the spare DCE channel unit 220 (N + 1) has its transmission rate returned from the uniform rate to the original rate. As a result, a serial signal composed of the transmission data signal SD and the transmission request signal RS defined in JIS X 5101 is restored. This serial signal is used as a working line terminating device 30 (x) or a spare line terminating device 30 (N).
Working line 40 (x) or protection line 4 via +1)
It is sent to 0 (N + 1).

The above is the operation of the line switching device 20 when the terminal device 10 (x) transmits a signal. Next, the operation of the line switching device 20 when the terminal device 10 (x) receives a signal will be described.

In this case, the transmission signal S specified by JIS X 5101 is transmitted from the communication partner of the terminal device 10 (x).
A serial signal composed of D and the transmission request signal RS is sent. This serial signal is sent through the working line 40 (x) if the working line 40 (x) is available. On the other hand, if the working line 40 (x) cannot be used, it is sent via the protection line 40 (N + 1).

Working line 40 (x) or protection line 40
The serial signal sent via (N + 1) is used as the working line termination device 30 (x) or the backup line termination device 30.
Via (N + 1), the current DCE channel unit 220
(X) or the spare DCE channel unit 220 (N +
1).

In this case, the transmission data signal SD and the transmission request signal RS are supplied as the reception data signal RD and the reception carrier detection signal CD, respectively. Further, in this case, not only the signals RD and CD but also the transmission enable signal CS is supplied together.

DCE channel unit 220 (x) or 2
The serial signal supplied to 20 (N + 1) has its transmission rate converted to a uniform rate. The serial signal converted into the uniform speed is transmitted through the line switching unit 230 to the DTE channel unit 21.
0 (x). DTE channel unit 210 (x)
The serial signal supplied to the device returns the transmission speed to the original speed. As a result, the received data signal RD defined by JIS X 5101, the received carrier detection signal CD,
A serial signal with the transmission enable signal CS is obtained. This serial signal is supplied to the terminal device 10 (x).

The above is the operation when the terminal device 10 (x) receives a signal. Next, referring to FIG.
The operation of the E channel unit 210 (x) will be described. First, the operation of the DTE channel unit 210 (x) when the terminal device 10 (x) transmits a signal will be described.

In this case, the serial signal composed of the transmission data signal SD and the transmission request signal RS output from the terminal device 10 (x) is transmitted via the DTE interface circuit 211 (x) of the DCE channel unit 210 (x). It is supplied to the mapping circuit 212 (x).

The serial signal supplied to the mapping circuit 212 (x) is allocated within a predetermined frame. This results in a serial signal with an intermediate speed that is an integral fraction of the uniform speed.

A specific example of this speed conversion will be described with reference to FIG. Signal S specified by JIS X 5101
The original speed of the serial signal composed of D and RS is shown in FIG.
, 0.6 Kb / s, 1.2 Kb / s, 2.
4 Kb / s, 4.8 Kb / s, 7.2 Kb / s, 9.6
Kb / s, 12.0 Kb / s, 14.4 Kb / s, 1
There is 9.2 Kb / s.

To set a uniform speed for time division multiplexing,
This unified speed may be set to a speed corresponding to a common multiple of the above-mentioned plurality of original speeds. However, doing so can significantly increase the speed of unification. Therefore, in this embodiment, first, the transmission speed of the signal is converted into an intermediate speed by mapping processing, and then the intermediate speed is converted into a uniform speed. This can prevent the unified speed from increasing.

FIG. 5 shows ITU as a mapping method.
-T Recommendation V. The case where the 110 mapping method is adopted and 64 Kb / s is adopted as the uniform speed is shown.

In this case, the original transmission rate is 0.6 Kb /
s, 1.2 Kb / s, 2.4 Kb / s, 4.8 Kb / s
Is converted to an intermediate speed of 8 Kb / s, and the original transmission speeds of 7.2 Kb / s and 9.6 Kb / s are converted to an intermediate speed of 16 Kb.
/ S, converted to the original transmission rate of 12.0 Kb / s, 1
4.4Kb / s, 19.2Kb / s, intermediate speed 32K
converted to b / s.

FIG. 6 shows ITU-T Recommendation V.38. The structure of a frame adopted by the 110 mapping method is shown. As shown in the figure, this frame can insert data for 10 octets. Further, this frame is provided with frame bits 0 and 1 for establishing frame synchronization, a data transfer bit Di for mapping the signals SD and RS, status bits Sj and X, and a speed display bit E. Has been. The number of bits Di used for mapping depends on the original speed of the signals SD and RD.

The serial signal converted into the intermediate speed by the mapping circuit 212 (x) is the speed matching circuit 213 (x).
Is converted into a serial signal with a uniform speed of 64 Kb / s.
This speed conversion is performed, for example, by data iterative processing. In this case, if the intermediate speed is 32 Kb / s,
The data is repeated twice, for example, in bit units.

The above is the operation of the DTE channel unit 210 (x) when the terminal device 10 (x) transmits a signal. Next, the operation of the DTE channel unit 210 (x) when the terminal device 10 (x) receives a signal will be described.

In this case, the uniform speed serial signal supplied from the line switching unit 230 is the speed matching circuit 213 (x).
Returns to the intermediate speed serial signal. This speed conversion is performed by, for example, a data thinning process.

The serial signal converted from the transmission rate to the intermediate rate is supplied to the mapping circuit 212 (x) and the signals RD, CD and CS are extracted from the frame. This allows
A serial signal with the original speed is obtained. This serial signal is supplied to the corresponding terminal device 10 (x) via the DTE interface circuit 210 (x).

The above is the operation of the DTE channel unit 210 (x) when the terminal device 10 (x) receives a signal. Next, referring to FIG. 3, the DCE channel unit 22
The operation of 0 (x) will be described.

First, the operation of the DCE channel unit 220 (x) when the terminal device 10 (x) transmits a signal will be described.

In this case, the uniform speed serial signal output from the line switching unit 230 is supplied to the working or standby speed matching circuit 221 (y) and is returned to the intermediate speed serial signal. This converted output is supplied to the working or spare mapping circuit 222 (y), and the original signals RD and CD are extracted from the frame. This gives a serial signal with the original speed.

This serial signal is supplied to the working or standby null modem circuit 223 (y) and the received data signal R
D is converted into a transmission data signal SD, and the reception carrier detection signal CD is converted into a transmission request signal RS.
As a result, the signal C defined by JIS X 5101
A serial signal having D and RS is obtained. This serial signal is
It is sent to the working or protection line terminating device 30 (y) via the DCE interface circuit 224 (y).

The above is the operation of the DCE channel unit 220 (x) when the terminal device 10 (x) transmits a signal. Next, the operation of the DCE channel unit 220 (x) when the terminal device 10 (x) receives a signal will be described.

In this case, the serial signal supplied from the working or protection line termination device 30 (y) is the DCE interface circuit 224 (y) and the null modem circuit 223.
(Y) and is supplied to the mapping circuit 222 (y) and converted into an intermediate speed serial signal. This serial signal is converted into a serial signal having a uniform speed by the speed matching circuit 221 (y).

The above is the operation of the DCE channel unit 220 (x) when the terminal device 10 (x) receives a signal. Next, the operation of the line switching unit 230 will be described with reference to FIG.

First, the operation when the terminal device 10 (x) transmits a signal will be described. In this case, the N serial signals supplied from the DTE channel units 210 (1), 210 (2), ..., 210 (N) are time-division demultiplexing / demultiplexing circuits 231.
By time division multiplexing. This time division multiplexing is performed so as to set a time slot of the sum (N + 1) of the number N of working lines and the number of protection lines 1 in one multiplexing period.

This time division multiplex output is the time switch 23.
3, and the time slots of the multiplexed signal can be exchanged between the working line 40 (x) and the protection line 40 (N + 1) as needed.

That is, if the working line 40 (x) is usable, the serial signal output from the DTE channel unit 210 (x) is positioned as it is in the time slot assigned to the working line 40 (x). It On the other hand, if the working line 40 (x) is unavailable, the serial signal is positioned in the time slot assigned to the protection line 40 (N + 1). As a result, the used line is switched from the working line 40 (x) to the protection line 40 (N + 1).

This line switching is controlled by the control unit 235 based on the command given by the user using the operation setting unit 234.

The time-division multiplexed signal output from the time switch 233 is demultiplexed by the second time-division demultiplexing / demultiplexing circuit 232 into each multiplexed signal and distributed to the corresponding DCE channel unit 220 (y). Thus, when the working line 40 (x) is available, the serial signal output from the DTE channel unit 210 (x) is the working DCE.
It is supplied to the channel unit 220 (x). On the other hand, when the working line 40 (x) is unavailable, the serial signal output from the DTE channel unit 210 (x) is supplied to the spare DCE channel unit 220 (N + 1).

The above is the operation of the line switching unit 230 when the terminal device 10 (x) transmits a signal. Next, the operation of the line switching unit 230 when the terminal device 10 (x) receives a signal will be described.

Also in this case, the DCE channel unit 220
The serial signals output from (1) to 220 (N + 1) are
After being time-division multiplexed by the second time-division demultiplexing / demultiplexing circuit 232, time slots are exchanged by the time switch 233 as needed. After this, the time switch 23
The output of No. 3 is demultiplexed for each multiplexed signal by the first time division demultiplexing circuit 231, and the DTE channel unit 210
(1) to 210 (N).

The above is the operation of the line switching unit 230 when the terminal device 10 (x) receives a signal.

[Effect] According to this embodiment described in detail above, there are the following effects.

(1) First, according to this embodiment, a function for converting the signal transmission rate from the original rate to a predetermined unified rate or for returning from this rate to the original rate is provided. The line switch can be performed by using the time switch 233.

As a result, the number of channels increases,
Even when it is necessary to perform a complicated switching operation, it is possible to prevent the line switching device from becoming complicated. Further, as a result, the hardware failure of the line switching device itself can be avoided.

(2) Further, according to this embodiment, when the signal transmission speed is converted to the uniform speed, the conversion speed is first converted to the intermediate speed and then to the uniform speed. It is possible to prevent the unification speed from increasing. Thereby, the structure of the speed conversion unit can be simplified.

[Other Embodiments] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment.

(1) First, in the above embodiment, the DTE
The case where the channel units 210 (1) to 210 (N), the DCE channel units 220 (1) to 210 (N + 1), and the line switching unit 230 are arranged in one place has been described. However, in the present invention, as shown in FIG. 7, these may be arranged at distant locations, and a line may be switched at distant locations by connecting them by a transmission circuit.

(2) Further, according to the above-described embodiment, the case where the signal transmission rate is converted into the uniform rate, and the conversion is performed after the conversion into the intermediate rate by the mapping process has been described. However, according to the present invention, when the uniform speed does not become so large, the data repetition
The original speed may be directly converted into the unified speed.

(3) Further, in the above embodiment, the case where the present invention is applied to a line switching device in which one line is provided as a protection line has been described. However, the present invention
It is also applicable to a line switching device in which a plurality of lines are provided as a backup line.

(4) Furthermore, in the above embodiment,
The case where the present invention is applied to the line switching device of the data transmission system in which the terminal device has the transmitting function and the receiving function has been described. However, the present invention is also applicable to a line switching device of a data transmission system in which a terminal device has only a transmission function or a reception function.

(5) In addition to this, the present invention can of course be variously modified without departing from the scope of the invention.

[0076]

As described in detail above, according to the present invention,
Since the function for converting the signal transmission speed from the original speed to the predetermined uniform speed or for returning the original speed to the unified speed is provided, the line can be switched using the time switch.

As a result, the number of channels increases,
Even when it is necessary to perform a complicated switching operation, it is possible to prevent the line switching device from becoming complicated. Further, as a result, the hardware failure of the line switching device itself can be avoided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a DTE channel unit.

FIG. 3 is a block diagram showing a configuration of a DCE channel unit.

FIG. 4 is a block diagram showing a configuration of a line switching unit.

FIG. 5 is a diagram for explaining the operation of the DTE channel unit.

FIG. 6 is a diagram showing a structure of a frame for mapping.

FIG. 7 is a block diagram showing a configuration of another embodiment of the present invention.

[Explanation of symbols]

 10 (1) to 10 (N) ... Terminal device 20 ... Line switching device 30 (1) to 30 (N) ... Working line terminal device 30 (N + 1) ... Spare line terminal device 40 (1) to 40 (N) ) ... Working line 40 (N + 1) ... Protection line 210 (1) to 210 (N) ... DTE channel unit 220 (1) to 220 (N + 1) ... DCE channel unit 230 ... Line switching unit 211 (x) ... DTE interface circuit 212 (x), 221 (y) ... Mapping circuit 213 (x), 221 (y) ... Speed matching circuit 223 (y) ... Null modem circuit 224 (y) ... DCE interface circuit 231, 232 ... Time division demultiplexing circuit 233 ... Time switch 234 ... Operation setting section 235 ... Control section

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H04Q 11/04 301 H04L 13/00 311

Claims (4)

[Claims] 1. A line switching device that is shared by a plurality of terminal devices having different signal transmission rates, and when the working line of each terminal device cannot be used, the working line of this terminal device is switched from the working line to the protection line. In the above, in each terminal device, a plurality of speed conversion means for converting the transmission speed of the transmission signal output from the corresponding terminal device from the original speed to a predetermined unified speed, and a plurality of speed conversion means The output signal is time-division-multiplexed, and the time-division-multiplexed output time slot is exchanged according to the line switching request. A plurality of speed reverse conversion means for returning the transmission speed of the signal supplied from the line switching means from the unified speed to the original speed. Line switching device characterized by. 2. The allocating means for allocating a transmission signal output from the corresponding terminal device to a predetermined frame to generate a signal having an intermediate speed which is an integral fraction of the uniform speed. And a speed matching means for converting the transmission speed of the signal output from the allocating means from the intermediate speed to the unified speed, wherein the line switching means changes the signal output from the plurality of speed converting means to the number of lines. Minute multiplexing means for time-division multiplexing so as to have time slots of minutes, time switching means for exchanging the time slots of the time-division multiplexed signal output from this multiplexing means in accordance with the line switching request, and the time switching means for outputting. And a separating means for separating the time-division multiplexed signal for each multiplexed signal and supplying each separated output to the corresponding speed inverse conversion means. The speed inverse conversion means converts the transmission speed of the signal supplied from the line switching means from the uniform speed to the intermediate speed, and the transmission from the frame of the signal output from the speed matching means. The line switching device according to claim 1, further comprising: an extracting unit that extracts a signal. 3. A line switching device for switching a working line of this terminal device from a working line to a protection line when a plurality of terminal devices having different signal transmission rates share the working line of each terminal device. A plurality of speed converting means provided for each line and converting the transmission speed of the reception signal sent through the corresponding line from the original speed to a predetermined unified speed, and the plurality of speed converting means. The signal output from is time-division multiplexed, and the time-division-multiplexed output time slots are exchanged in accordance with the line switching request, and the line switching means for switching the used line from the working line to the protection line and each terminal device And a plurality of speed inverse conversion means for returning the transmission speed of the signal supplied from the line switching means from the uniform speed to the original speed. Line switching device characterized by 4. The allocation which the speed conversion means generates a signal having an intermediate speed which is an integral fraction of the uniform speed by allocating the received signal sent through the corresponding line to a predetermined frame. Means and speed matching means for converting the transmission speed of the signal output from the allocating means from the intermediate speed to the uniform speed, the line switching means from the speed matching means of the plurality of speed converting means. Time-division multiplexing means for time-division multiplexing output signals, time switch means for exchanging time slots of time-division multiplexed signals output from this multiplexing means according to a line switching request, and time-division multiplexing output from this time switching means Separation means for separating the multiplexed signal for each multiplexed signal and supplying each separation output to the corresponding speed inverse conversion means, the second speed The conversion means converts the transmission speed of the signal supplied from the line switching means from the uniform speed to the intermediate speed, and the received signal from the frame of the signal output from the speed matching means. 4. The line switching device according to claim 3, further comprising extraction means.