JP3460144B2 - Line connection method and line connection 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 technique for connecting a high speed digital leased line to an ISDN subscriber line of a primary group interface.

[0002]

2. Description of the Related Art An ISDN subscriber line of a primary interface (23B + D) represented by ISDN primary speed is
Since it has 23 information channels (B channels), it can be connected to a large number of terminals when installing PBX, which is convenient, but this service is available in areas where ISDN primary group subscriber lines are not installed. I can't receive it.

In order to solve this, conventionally, there has been a method of extending a subscriber line of ISDN primary group speed by a high-speed digital leased line made of a metal wire.

For example, as shown in FIG. 10, a subscriber line 1a connected to an ISDN primary group speed exchange 1 is connected to a leased line 11 of a leased line network through a line connection device 10 and a PBX or the like. The terminal 2 of the above is connected to the leased line 11 of the leased line network via the DSU 3 for ISDN primary group speed and the line connecting device 10 so that the terminal 2 can be used as a subscriber terminal of ISDN primary group speed. There is.

Thus, the IS of the primary group interface is
When connecting the DN subscriber line and the high-speed digital leased line, it is necessary to consider the difference in transmission speed and the difference in the number of bits per frame.

That is, in the ISDN primary rate line,
As shown in 1 (a), a 1-bit frame bit F in which control information for fault isolation, a check bit for code error monitoring, and the like are multiplexed, and 23 B bits of 8 bits.
193 channels B1 to B23 and one D channel D
One frame of bits is configured and 125 per frame
The data is transmitted at a data rate of μs, that is, 1.544 Mbps.

On the other hand, in the high-speed digital leased line, one frame is composed of 24 time slots TS1 to TS24 in 8-bit units as shown in FIG.
125 μs per frame, that is, 1.536 Mbps
It is transmitting at the data rate of.

Therefore, even if the ISDN primary group velocity data is simply relayed to the dedicated line side, one bit of data cannot be transmitted per frame.

For this reason, conventionally, a method of transmitting only 192 bits of data to the leased line side from the frame of ISDN primary group speed by the line connection device 10 or a method of transmitting 23 information by the line connection device 10 is used. A method of using one of the channels for frame bit transmission or a method of transmitting frame bits to the dedicated line side using another line has been used.

[0010]

[Problems to be Solved by the Invention] However, ISD
In the method of transmitting only 192 bits of data excluding the frame bit F from the frame of N primary group speed, the control bit multiplexed in the frame bit cannot be used, and, for example, a failure occurs. In this case, there is a problem that the loopback test control signal is not transmitted, so that it cannot be separated or that the code error cannot be monitored.

Further, if one time slot is used for frame bit transmission, data cannot be transmitted for one channel, the function of ISDN primary group speed is limited, and it is inconvenient when a PBX is used as a terminal. is there.

Further, in the method of transmitting frame bits by using another line, there is a cost for installing another line,
There is a problem of high cost.

An object of the present invention is to provide a line connecting method and a line connecting device which solve such a problem. It should be noted that the present invention solves the above-mentioned problem by paying attention to the fact that the information transfer amount of the D channel of ISDN is relatively small and there is always a sufficient margin at the data rate of 64 kbs.

[0014]

In order to achieve the above object, the line connection method according to claim 1 of the present invention is a line connection method for connecting a high speed digital leased line to an ISDN subscriber line of a primary group interface. In the step of extracting D channel data of a predetermined speed included in the signal input from the ISDN subscriber line, the step of storing the extracted D channel data, and the step of storing the stored D channel data in the predetermined value. Reading at a speed of 7/8 of the speed and generating frame bits for sending to the high-speed digital dedicated line at a speed of 1/8 of the predetermined speed; the read D channel data and the generation And multiplexing the multiplexed frame bits and the multiplexed data at the predetermined speed at a specific target of the high-speed digital leased line. Inserting the multiplexed data, which is inserted into the specific time slot of the signal input from the high-speed digital leased line at the predetermined speed, into the signal slot; Separating the D channel data of 1 bit and the frame bit of 1 bit, accumulating the separated D channel data, reading the accumulated D channel data at the predetermined speed, and the ISDN subscriber line. And a step of outputting to.

A line connection device according to a second aspect of the present invention is a line connection device for connecting a high speed digital leased line to an ISDN subscriber line of a primary group interface, wherein a signal input from the ISDN subscriber line. Received,
D channel data extraction means (21) for extracting D channel data at a predetermined speed from the signal, and a first buffer (2
7), a first data writing means (26) for storing the D channel data extracted by the D channel data extracting means in the first buffer, and D channel data stored in the first buffer. Is 7/8 of the specified speed
And a first frame bit generating means (29) for generating a frame bit to be transmitted to the high-speed digital leased line side at a speed ⅛ of the predetermined speed. A multiplexing means (31) for multiplexing the data output from the first reading means and the frame bits generated by the first frame bit generating means with the data of the predetermined speed; Multiplexed data output means (22) for inserting data into a specific time slot of the high-speed digital leased line and outputting it.
A multiplexed data extracting means (22) for receiving a signal from the high-speed digital leased line and extracting the multiplexed data inserted in the specific time slot at the predetermined speed from the signal; Separation means (36) for separating the multiplexed data extracted by the extraction means into 7-bit D channel data and 1-bit frame bit
A second buffer (38), and second data writing means (37) for accumulating in the second buffer the D channel data having a speed of 7/8 of the predetermined speed separated by the separating means. A second data reading means (39) for reading the D channel data accumulated in the second buffer at the predetermined speed, and a frame bit for sending to the ISDN subscriber line side at a predetermined speed of 1 Second frame bit generation means (40) for generating at a transmission rate of / 8
And separated data output means (21) for outputting the D channel data output from the second reading means and the frame bits output from the second frame bit generation means to the ISDN subscriber line. It is characterized by having.

A line connecting device according to a third aspect of the present invention is the line connecting device according to the second aspect, wherein the first data writing means is the D channel data extracted by the D channel data extracting means. It is configured to remove the idle flag and write to the first buffer, and the first data reading means outputs the idle flag instead of the data when there is no data to read in the first buffer. The second data writing unit is configured to remove the idle flag from the D channel data separated by the separating unit and write the idle flag into the second buffer, and the second reading unit is configured to:
When there is no data to read in the second buffer, an idle flag is output instead of the data.

[0017]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an implementation of connecting between an ISDN primary group speed subscriber line 1a and a dedicated line 11 in the same manner as the line connection device 10 shown in FIG. 10 in order to extend an ISDN primary group speed subscriber line. Line connection device 20
Shows the configuration of.

In FIG. 1, the interface 21 is I
An interface for a subscriber line 1a of SDN primary group speed, which converts an optical signal from the exchange 1 into an electric signal, a frame bit Fa of 1 bit, 23 B channel data B1 to B23 of 8 bits, The 8-bit D channel data Da is extracted, the B channel data B1 to B23 are output to the second multiplexing means 42 described later, and the frame bit Fa and the D channel data Da are multiplexed processing section 2 described later.
Output to 5. The speed of the B channel data B1 to B23 and the D channel data D extracted by the interface 21 is 64 kbps, and the speed of the frame bit Fa is 8 kbps.

The interface 21 is a third interface which will be described later.
The frame bit Fd from the demultiplexing unit 35 is added to the data from the multiplexing means 43 to form one frame and output to the subscriber line 1a side.

The interface 22 is an interface for the leased line 11, receives a signal from the leased line side in frame units, extracts 8-bit data of each of the time slots TS1 to TS24, and extracts each of the time slots TS1 to TS23. The data is output as B channel data B1 to B23 to the third multiplexing means 43, and the time slot TS24
And outputs the data to the separation processing unit 35 as the multiplexed data De. The speed of each B channel data B1 to B23 and the multiplexed data De output from the interface 22 is 64 kbps.

The interface 22 receives the data from the second multiplexing means 42 in the time slots TS1 to TS2.
4 and forms one frame to output to the dedicated line 11 side.

The D channel data Da output from the interface 21 is input to the first data writing means 26 of the multiplex processing unit 25. The first data writing means 26
D channel data D output from the interface 21
The idle flag Fi is removed from a and only the data Db to be transmitted is written in the buffer 27.

The idle flag Fi is an 8-bit specific flag that the ISDN interface continuously transmits on the D channel when there is no data to be transmitted.

The data Db stored in the buffer 27 is
The data is sequentially read by the first data reading means 28 at a speed of 56 kbps and output to the first multiplexing means 31 described later. The first data reading means 28 outputs the idle flag Fi to the first multiplexing means 31 at a speed of 56 kbps instead of the data while there is no data to be read in the buffer 27.

The frame bit generation means 29 is a frame bit Fb for each frame of data transmitted to the dedicated line side.
Is generated and is output to the first multiplexing means 31 at a speed of 8 kbps.

Of the frame bits Fa output from the interface 21, the frame bit generation means 29 outputs the information about the multi-frame synchronization pattern, the bit for maintenance, monitoring and test control of the line (called m bit). Regarding the bits for relaying and error checking, the second multiplexing means 4 for multiplexing the output of the first multiplexing means 31 and the B channel data B1 to B23.
CRC calculation means 3 for performing CRC calculation on the output of 2
A frame bit is generated based on the operation result of 0.

The first multiplexing means 31 multiplexes the 56 kbps data Dc output from the first data reading means 26 and the frame bit Fb output from the frame bit generating means 29 at 8 kbps to 64 kbp.
The multiplexed data Dd multiplexed on s is input to the second multiplexing means 42, and B is output from the interface 21.
It is multiplexed with the channel data B1 to B23 and output to the interface 22.

On the other hand, the separation means 36 of the separation processing section 35 is
The 7-bit D channel data Df and the 1-bit frame bit Fc are separated from the multiplexed data De output from the interface 22. The speed of the D channel data Df is 56 kbps and the speed of the frame bit Fc is 8 kb.
ps.

The D channel data Df output from the separating means 36 is input to the second data writing means 37.
The second data writing means 37 removes the idle flag Fi from the D channel data Df output from the separating means 36, and writes only the data to be transmitted to the buffer 38.

The data Dg stored in the buffer 38 is
B channel data B1 to B23 from the interface 22 are sequentially read by the second data reading means 39 at a speed of 64 kbps and input to the third multiplexing means 43.
And is output to the interface 21. Here, the second data reading means 39 outputs an 8-bit idle flag Fi to the third multiplexing means 43 at a speed of 64 kbps instead of the data while there is no data to be read in the buffer 38.

The frame bit generation means 40 generates a frame bit Fd for each frame of data to be transmitted to the subscriber line 1a side, and outputs this to the interface 21 at a speed of 8 kbps.

Of the frame bits Fc output from the interface 22, the frame bit generation means 40 provides the information on the multi-frame synchronization pattern, the bit for maintenance, monitoring and test control of the line (called m bit). Regarding the bits for relaying and error checking, CR for the output of the third multiplexing means 43
A frame bit is generated based on the calculation result of the CRC calculation means 41 that performs the C calculation.

Next, the operation of the line connection device 20 will be described. Regarding B channel data, separation by the interfaces 21 and 22 and second and third multiplexing means 42,
Since only the multiplexing process by 43 is performed and no special process is performed and the data is transmitted to both sides via the interfaces 21 and 22, the D channel will be described below.

First, the case of transmitting data from the ISDN primary group velocity side to the leased line side will be described.

As shown in FIG. 2A, 8-bit data Da1 (= d ₁₁ , d ₁₂ ,
, D ₁₈ ) to Da 5 (d ₅₁ , d ₅₂ , ..., d ₅₈ ) are input, and subsequently data Da 6 to Da composed of idle flags are input.
8 is input, and data Da9 (= d ₆₁ , d ₆₂ ,
, D ₆₈ ), Da10 (d ₇₁ , d ₇₂ , ..., d ₇₈ ), are input, and in synchronization with this, the frame bits Fa1, Fa2, ... Are input as shown in FIG. Suppose

In this case, the first data writing means 26 of the multiplex processing section 25 causes the idle flags Fi1, Fi2,
The removed data Db1, Db2, ... Are written in the buffer 27 as shown in FIG.

The data written in the buffer 27 is the first
4 is sequentially read by the data reading means 28 at a speed of 56 kbps, which is 7/8 of 64 kbps. However, when the data runs out during reading, the idle flag Fi is inserted, so that the first multiplexing means 31 of FIG. The data Dc1, Dc2, ... Shown in (a) are output at a speed of 56 kbps.

The data Dc1, Dc2, ... Are data in 7-bit units because the read speed is 56 kbps, which is 7/8 of 64 kbps. In parallel with this, as shown in FIG. 4B, the frame bit generation means 29 generates frame bits Fb1, Fb2, ... And outputs them to the first multiplexing means 31 at a speed of 8 kbps.

As shown in FIG. 5, the first multiplexing means 31 sets each frame bit Fb1, Fb2, ... Output from the frame bit generation means 29 as the head bit, and the data Dc1, Dc2 ,. Are added to each other and multiplexed at 64 kbps, and the multiplexed data Dd1, Dd2, ... In 8-bit units are input to the second multiplexing means 42, multiplexed with the B channel data, and output to the interface 22.

The data multiplexed by the second multiplexing means 42 is inserted by the interface 22 into the time slots TS1 to TS24 of the dedicated line 11 to be added to the dedicated line 11.
The multiplexed data Dd is inserted into the specific time slot TS24 and output to the dedicated line. Here, since the transmission rates of the B channel data B1 to B23 and the multiplexed data Dd are 64 kbps, respectively, the transmission rate of the data for the dedicated line is 1.536.
Mbps (= 64k x 24), 1.5M dedicated line
Match the data rate of the logical path.

On the contrary, when the multiplexed data De1, De2, ... Shown in FIG.
7-bit data Df1 shown in (a) of FIG.
, And 1-bit frame bits Fc1, Fc2, ... Shown in FIG. 7B.

Then, the data Dg1, Dg2, ... With the idle flag removed from the data Df1, Df2, ... By the second data writing means 37 are written in the buffer 38 as shown in FIG.

Data Dg written in the buffer 38
, Dg2, ... Are sequentially read by the second data reading means 39 at a speed of 64 kbps, and the idle flag Fi is inserted when there is no more data to read, so that the third multiplexing means 43 has a configuration shown in FIG. As shown in (a) of
D-channel data Dh1, Dh2, ... In 8-bit units are output, and data obtained by multiplexing this D-channel data Dh and B-channel data from the interface 22 is output to the interface 21. In parallel with this, the frame bit generation means 40 outputs the frame bits Fd1, Fd2, ... To the interface 21 as shown in FIG.

The interface 21 adds the frame bit Fd to the data multiplexed by the third multiplexing means 43 to form one frame and outputs it to the subscriber line 1a. The data transmission rate for the subscriber line is 1.544 Mbps
(= 64k × 24 + 8k), which matches the data rate of the subscriber line.

Since the data rate on the ISDN primary group velocity side is slightly higher than the data rate on the leased line side, I
When data is transmitted from the SDN primary group speed side to the leased line side, the idle flag Fi as shown in FIGS.
When the data is transmitted from the leased line side to the ISDN primary group velocity side, the number of idle flags Fi increases as shown in FIGS. 6 to 9. In this way, the removal and insertion of the idle flag absorbs the difference in transmission rate due to the multiplexing, so that the D channel data and the frame bits can be smoothly multiplexed and separated.

Thus, the line connection device 20 of the embodiment
Transmits the multiplexed frame bits F and D channel data on the ISDN primary group speed side to the dedicated line side, and extracts the D channel data and frame bits from the multiplexed data inserted in the specific time slot on the dedicated line side. Separated and ISD
The transmission is made to the N primary group velocity side.

Therefore, the information of the ISDN primary group speed line can be transmitted to the leased line side without being damaged, and the leased line section can be separated and the ISDN primary group speed line section can be separated and tested when a failure occurs. Further, line error monitoring can be performed not only in the leased line section but also in the ISDN primary group speed line section.

Further, since it is not necessary to transmit the control information on another line, the cost can be reduced.

In the present invention, the information transfer amount of the D channel is reduced by 1 bit from the original information transfer amount by the frame bit, but as described above, the information transfer amount of the ISDN D channel is small and is 64 kbs. There is always a sufficient margin for the data rate, and 56 kbps does not cause any problems.

[0050]

As described above, the line connecting method and the line connecting apparatus of the present invention are provided with the primary group interface I.
SDN frame bits are multiplexed with D channel data, inserted in a specific time slot of a dedicated line and transmitted, and D channel data and frame bits are extracted from the multiplexed data inserted in a specific time slot of the dedicated line. It is separated and transmitted to the ISDN primary group velocity side.

Therefore, the ISD of the primary group interface is
Information on N lines can be transmitted to the leased line side without loss, and in the event of a failure, the leased line section can be separated and the ISDN line section can be separated and tested. Further, line error monitoring can be performed not only in the leased line section but also in the ISDN line section.

Further, since it is not necessary to transmit information on another line, it is possible to prevent cost increase.

Further, by removing and inserting the idle flag in the D channel data, the difference in transmission rate due to multiplexing is absorbed, so that data transmission between the subscriber line and the leased line is performed. It can be done smoothly.

[Brief description of drawings]

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

FIG. 2 is a data diagram for explaining the operation of one embodiment.

FIG. 3 is a data diagram for explaining the operation of one embodiment.

FIG. 4 is a data diagram for explaining the operation of one embodiment.

FIG. 5 is a data diagram for explaining the operation of the embodiment.

FIG. 6 is a data diagram for explaining the operation of the embodiment.

FIG. 7 is a data diagram for explaining the operation of the embodiment.

FIG. 8 is a data diagram for explaining the operation of the embodiment.

FIG. 9 is a data diagram for explaining the operation of the embodiment.

FIG. 10 is a diagram showing a configuration when a subscriber line is extended by a dedicated line.

FIG. 11 is a diagram showing a frame on the subscriber line side and a frame on the leased line side.

[Explanation of symbols]

1a Subscriber line 11 dedicated line 20 line connection device 21,22 interface 25 Multiple processing unit 26 First Data Writing Means 27 buffers 28 First data reading means 29 frame bit generation means 30 CRC calculation means 31 First Multiplexing Means 35 Separation processing unit 36 Separation means 37 Second data writing means 38 buffers 39 Second data reading means 40 frame bit generation means 41 CRC calculation means 42 Second multiplexing means 43 Third Multiplexing Means

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Kaku 3-19-3 Nishishinjuku, Shinjuku-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Shinichi Maki 19-19 Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Nihon Telegraph and Telephone Corporation (56) Reference JP 10-23571 (JP, A) JP 4-292046 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) H04L 29/08 H04J 3/00 H04L 12/02 H04M 3/00 H04M 11/00 303

Claims (3)

(57) [Claims] 1. A line connection method for connecting a high-speed digital leased line to an ISDN subscriber line of a primary group interface, wherein D channel data of a predetermined speed included in a signal input from the ISDN subscriber line is extracted. A step of accumulating the extracted D channel data, a step of accumulating the accumulated D channel data at the predetermined speed
The frame bit to be read out at the speed of 8 and transmitted to the high-speed digital leased line is set to the predetermined speed of 1
/ 8, generating the multiplexed D-channel data and the generated frame bits, and multiplexing the multiplexed data at a predetermined speed to the high-speed digital signal only. Inserting into a specific time slot of the line; extracting the multiplexed data inserted at the predetermined speed into the specific time slot of the signal input from the high speed digital dedicated line; Separating the multiplexed data into 7-bit D-channel data and 1-bit frame bit, storing the separated D-channel data, reading the stored D-channel data at the predetermined speed, Outputting to the ISDN subscriber line. 2. A line connection device for connecting a high-speed digital leased line to an ISDN subscriber line of a primary group interface, receiving a signal input from the ISDN subscriber line, and receiving D channel data of a predetermined speed from the signal. D channel data extracting means (21) for extracting the D channel data, a first buffer (27), and first data writing for accumulating the D channel data extracted by the D channel data extracting means in the first buffer. Means (26), a first data reading means (28) for reading the D channel data accumulated in the first buffer at a speed of 7/8 of the predetermined speed, and for sending to the high speed digital leased line side Output from the first reading means and the first frame bit generating means (29) for generating the frame bits of the frame at a speed which is ⅛ of the predetermined speed. Data and the frame bit generated by the first frame bit generation means, the multiplexing means (31) for multiplexing the data at the predetermined speed, and the multiplexed data at a specific time of the high-speed digital leased line. A multiplexed data output means (22) for inserting and outputting in a slot, and a signal from the high-speed digital leased line, and extracting the multiplexed data inserted in the specific time slot at the predetermined speed from the signal A multiplexed data extracting means (22) for separating, the separating means (36) for separating the multiplexed data extracted by the multiplexed data extracting means into 7-bit D channel data and 1-bit frame bit, Buffer (38) and 7/8 of the predetermined speed separated by the separating means
Second data writing means (37) for accumulating D channel data at a speed of 2 to the second buffer, and second data reading for reading D channel data accumulated at the second buffer at the predetermined speed. Means (39)
And second frame bit generation means (40) for generating frame bits to be transmitted to the ISDN subscriber line side at a transmission rate of 1/8 of the predetermined rate, and output from the second reading means. A line connection device, comprising: D channel data for outputting and frame data output from the second frame bit generating means to separate data output means (21) for outputting to the ISDN subscriber line. 3. The first data writing means is configured to remove an idle flag from the D channel data extracted by the D channel data extracting means and write the idle flag into the first buffer. Data reading means is configured to output an idle flag instead of the data when there is no data to read in the first buffer, and the second data writing means is D separated by the separating means. It is configured to remove the idle flag from the channel data and write it to the second buffer, and the second reading means outputs an idle flag instead of the data when there is no data to read in the second buffer. The line connection device according to claim 2, wherein the line connection device is configured as described above.