JPH10308739A - Cell multiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To convert data that are from plural communication terminals into cells, to effectively use a transmission line, multiplexing cells which have different speeds to plural other parties and also to perform data communication without cell loss. SOLUTION: This multiplexer has a cell conversion control part 22 which consists of plural different destination buffers 221, a cell generation circuit 222, a cell transfer control circuit 223, a different destination information storing part 224, a highway I/F part 225, a data bus I/F part 226 and plural timing generation circuits 227 and 228, and performs multiplexing data transmission among cell multiplexers. In such cases, data which is inputted from a communication terminal that has X.21 and V.35 interfaces is stored in a data buffer, stored data are successively transferred to the different destination buffer, and stored data are sent onto the transmission line in each destination in a prescribed transfer mode, transfer speed and transfer timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system in a communication network, and more particularly to data communication and voice communication in a B-ISDN network and a high-speed digital leased line, and more particularly, to a different transfer mode to a plurality of destinations. The present invention relates to a cell multiplexing device for performing cell transfer at a transfer speed and at a transfer speed.

[0002]

2. Description of the Related Art Generally, data communication and voice communication between communication terminals using a B-ISDN network or a high-speed digital leased line are performed via a terminal adapter. To use a B-ISDN network or a high-speed digital leased line, the communication speed (transmission capacity) to be used
And make a contract for the communication line accordingly. When using a dedicated line, it is necessary to keep the communication speed from exceeding the peak rate.
When performing logical multiplex communication using many communication channels,
It is common to contract for a communication line with a transmission capacity with some margin.

[0003] Usually, as the transmission capacity of a contracted communication line increases, the usage fee increases. Therefore, in order to keep the usage fee low, it is necessary to reduce the used transmission capacity. However, when the transmission capacity of the contracted communication line is small, the peak rate may be exceeded. Normally, data when the peak rate is exceeded is discarded. Therefore, conventionally, a contract for a communication line having a transmission capacity not exceeding the peak rate has been made. However, such contracts are inefficient because actual communication rarely uses the transmission capacity at the time of contract. In addition, there are data for which transmission delay is allowed and data which is not allowed due to the nature of the transfer data.Therefore, there are data for which a band must always be secured, and data which can be transmitted using an available band. Due to the difference in the method of securing the band, it has to be realized by separate devices, and there is a problem of inefficiency.

[Problems to be solved by the invention]

Accordingly, the present invention has been made in view of the above problems, and uses a communication line with a transmission capacity as small as possible, efficiently uses the communication line without exceeding a contracted peak rate, and transmits data and voice data. It is an object of the present invention to provide a cell multiplexing apparatus in which the cost related to communication is suppressed while the transmission quality of the cell is stabilized, and different bands are secured by one apparatus depending on the characteristics of transfer data.

[0005]

In order to achieve the above object, a cell multiplexing apparatus according to the present invention comprises: means for setting a transfer mode, a transfer speed peak rate, and a transfer guarantee speed for each transfer destination; Means for calculating and guaranteeing a transfer band from transfer mode and line transfer speed setting values, and cell transmission priority determining means using a transfer table for storing transfer request information and transfer mode information corresponding to a transfer peak speed. .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cell multiplexing apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a system to which a cell multiplexer according to the present invention is applied.

A cell multiplexing device (CLA) according to the present invention
D) 2 is a communication terminal device 5a, 5b whose communication amount fluctuates at a low speed represented by a personal computer;
When the communication volume such as CM voice communication is constant. B. X. 5c,
A communication terminal device 5d, such as a router, having a high-speed communication amount fluctuating and connected to the partner cell multiplexer 2 'via a B-ISDN, a 6.3M cell relay network 3, or a high-speed digital leased line 4. 5a ', 5b', 5c
', 5d'1, 5d'2.

FIG. 2 is a block diagram of the cell multiplexing apparatus 2 according to the present invention.

[0009] The cell multiplexing device 2 is a terminal device control unit 24 to 27 for controlling transmission and reception of data to and from a communication terminal device.
An ATM / high-speed digital leased line interface control unit 23 for controlling transmission / reception of data to / from the B-ISDN network or the high-speed digital leased line; and a cell conversion control unit 22 for sequentially converting data received from the terminal device control unit into cells.
, A general control unit 21 for performing general control of each control unit, a data bus 28, and a highway 29. The transmission rates of the terminal device control units 24 to 27 vary depending on the type of communication terminal device to be connected. For example, the terminal device control unit (HSD 6M interface unit) 26
Is connected to the PBX 5c, and the terminal device control unit (HSD1.5M or HSD128K interface unit) 27 is connected to the router 5d. In addition, the terminal device control unit (V.35)
The communication terminal device 5a is connected to the interface unit 24, and a terminal device control unit (X.21 interface unit)
The communication terminal device 5b is connected to 25.

A terminal device control unit (HSD 6M interface unit) 26 and a terminal device control unit (HSD 1.5M
Alternatively, the HSD128K interface unit) 27 is connected to the cell conversion control unit 22 by the highway bus 29.
The terminal device control unit (V.35 interface unit) 24 and the terminal device control unit (X.21 interface unit) 25 are connected to the cell conversion control unit 22 by a data bus 28. The terminal device control units 24 to 27 are connected to the communication terminal devices 5a to 5d of FIG.

Next, the operation of the cell multiplexer according to the present invention will be described. FIG. 3 shows a terminal control unit (HSD1.5M
3 shows a frame format of an I / F unit 27. Frame format 3 input to terminal control unit 27
The input data having (A) includes time slots TS1 to TS24 storing 8-bit serial data and a multi-frame synchronization bit F. The terminal device control unit 27 transfers the received data 3 (B) to the cell conversion control unit 22 via the highway 29 in which a time slot for storing 8-bit serial data is configured by TS1 to TS96. The cell conversion control unit 22 is connected to the highway 2
When TS1 to TS24 of received data 3 (B) from No. 9 are stored and become 47 bytes, a cell header is added to
(C), and transfer to the ATM / high-speed digital dedicated line I / F control unit 23. ATM / High-speed digital leased line I /
The F control unit 23 has a frame format 3 of HSD6M
(D) is generated, cells are sequentially placed in the time slots of TS1 to TS96, and transmitted to the line.

Terminal device control unit (X.211 / F unit) 25
X. shown in FIG. Data is input in the format of 21 HDLC. Terminal device control unit X. 21 I
The / F unit 25 extracts A (address field), C (control field), and D (data field) from the input data, adds a transfer header including a port position and a frame length, and adds an AAL5CPCS-PDU trailer to format data. 4 (B) and the data bus 2
8 and transferred to the cell conversion control unit 22. The cell conversion control unit 22 detects the range of the CPCS-PDU, that is, the data transfer range, from the frame length of the transfer header of the received data 4 (B). Further, the correspondence information between the port position registered from the dam terminal 6 in FIG.
It is set in the cell conversion control unit 22 via the data bus 28, generates VPI and VCI of the ATM header, and adds the ATM header to form format data 4 (C).
M / High-speed digital dedicated line I / F control unit 23 Hereinafter, the same operation as the cell transfer from the terminal device control unit 27 is performed.

Next, cell transfer will be described. Cell transfer methods include CBR (Constant Bit Rate) transfer method, VB
R (Variable Bit Rate) transfer method, ABR (Avairable Bi
t Rate) transfer method and UBR (Unspecified Bit Rate) transfer method, and transfer is performed by combining these methods. This transfer state is shown in FIG. The CBR transfer method is
This is a cell transfer method in which the transfer speed of a cell is always constant and its transfer band must always be secured. VBR
The transfer method is a cell transfer method in which the transfer speed of a cell varies, but a transfer band of the highest bit rate must be secured. The ABR transfer method is a cell transfer method in which the transfer speed of a cell varies, but transfer is performed at a certain fixed speed, and a transfer band of the lowest bit rate must always be secured. UB
The R transfer method is a cell transfer method in which the transfer speed of a cell varies, but the transfer may be performed using an empty band, and it is not necessary to always secure the transfer band.

Accordingly, a transfer band 31 for CRB cell transfer is always secured in the transmission lines 3 and 4 with a constant bandwidth, and CBR cells are always transferred. In addition, a transmission band 32 of the highest bit rate for VBR cell transfer is always secured in the transmission paths 3 and 4 with a constant bandwidth.
The cell is transferred. When there is a margin in the bit rate of the VBR cell in the transfer band 32, the UBR cell is transferred using the transfer band corresponding to the margin. Further, the transmission path 3,
4 is used as the transfer band of the ABR cell, and when there is a margin in the transfer bit rate of the ABR cell, the transfer band of the surplus is used for the UBR cell. Perform a transfer.

When performing the ABR transfer method and the UBR transfer method, the data input 4 (A) from the communication terminal devices 5a and 5b in FIG. 1 may exceed the data output to the line. As a control method without data discarding, the configuration and operation of the terminal device control units 24 and 25 having the function of limiting the flow rate of the ABR transfer data and UBR transfer data from the communication terminal devices 5a to 5b according to the data output state will be described with reference to FIG. Will be explained. The data from the communication terminal devices 5a to 5b is transmitted to the HDL by the SIO 253 via the terminal device I / F unit 252.
The flag (F) detection and CRC (data error detection) of C4 (A) are performed, and the serial data of the address part (A), the control part (C), and the data part (D) are converted into 8-bit parallel data. Transfer to buffer 255. The control unit 251 converts the data in the data buffer 255 into a data format 4 (B) in which a trailer of a CPCS-PDU and a transfer header (port position, frame length) are added, and the data is converted via a data bus I / F unit 256. The data is transferred to the cell conversion control unit 22.

In the case of the UBR transfer method, the control unit 251 sets the same speed as the maximum speed that the line can transfer to the clock generation circuit 254. The clock generation circuit 254 generates the set speed, and outputs the SIO 253 and the terminal device I.
/ F252 to the communication terminal devices 5a and 5b.
The communication terminal devices 5a and 5b transfer data to the terminal device I / F 252 in synchronization with the clock.

If the band of the line is occupied by the data of the CBR transfer method and the data of the VBR transfer method from another terminal device control unit, the data in the data buffer 255 cannot be transferred to the cell conversion control unit 22. Stay. Control unit 251
Detects that the data in the data buffer 255 has stayed for a certain amount or more, and sets the clock generation circuit 254 to reduce or stop the clock speed. Based on this setting, the clock generation circuit 254 controls the clocks of the terminal device I / F unit 252 and the SIO 253. The communication terminal devices 5a and 5b transfer data in synchronization with the clock, and thus limit data input. Control unit 251
Detects that the amount of staying data in the data buffer 255 has fallen below a certain amount, and resets the clock generation circuit 254 to the original maximum line transfer speed. By repeating this operation, a UBR transfer method without data discard is performed.

Therefore, the current usage of the communication line is grasped by means for storing data in the data buffer 255 and means for monitoring the amount of data in the data buffer. The communication terminal devices 5a, 5b are detected by means for detecting that a certain amount or more of data is stored in the data buffer 255 in the communication terminal 25, and restricting the inflow of data to the communication terminal devices 5a, 5b.
b, the data is accepted by the means for releasing the restriction on the data inflow to the communication terminal devices 5a and 5b when the free space of the buffer in the terminal device controller 25 has increased to some extent. As a result, it is possible to perform data communication without discarding data while using almost 100% of the transmission capacity of the communication line contracted for data from the communication terminal devices 5a and 5b.

Next, a control method for cell transfer to a plurality of destinations in a plurality of transfer modes and a plurality of transfer speeds will be described with reference to FIGS. The cell conversion control unit 22 includes:
A plurality of destination-specific buffers 221-1 to 221-128;
Cell generation circuit 222, cell transfer control circuit 223, destination-specific information storage section 224, highway I / F section 225
, A data bus I / F unit 226, and a plurality of transfer timing generation circuits 227 to 228.

From the dam terminal 6 for each transfer destination,
(1) Which transfer mode is the CBR transfer mode, VBR transfer mode, ABR transfer mode, or UBR transfer mode? (2) Transfer speed from 64 Kb / s to 6
Information on which speed out of Mb / s
Transfer to 1. The overall control unit 21 calculates the received information according to the following to secure a transfer band.

ΣCBR + ΣVBR + ΣABR + ≦ line cell transfer speed (1)

That is, the sum of the transfer speeds in the CBR transfer mode, the sum of the maximum transfer speeds in the VBR transfer mode,
If the sum of the minimum transfer speeds in the ABR transfer mode is lower than or equal to the line cell transfer speed (maximum transmission capacity), information from the dam terminal 6 is accepted. By this verification, even if all cell transfers occur at the same time, the transfer bandwidth of each transfer mode is guaranteed.

FIG. 8 is a diagram showing an example of the configuration of a transfer management table of the cell conversion control unit 22. FIG. 9 is an operation flowchart of the cell transfer control unit. Terminal device control unit 24-
The VBR data, AVR data, and UBR data 4 (B) from the data bus 27 via the data bus 28
Through the F unit 226, destination-specific buffers 221-1 to 221-2
It is stored in any of 1-128. On the other hand, the CBR data passes through the highway 29, passes through the highway I / F unit 225, and is stored in the destination buffers 221-1 to 221-1.
28. Information on cell transfer is set in the destination information storage unit 224 from the central control unit 21 via the data bus 28 and the data bus I / F 226. Based on the destination-specific information in the destination-specific information storage unit 226, the cell transfer speed is set in the transfer timing generation circuit (1) 227 to the transfer timing generation circuit (10) 228, and the cell transfer control circuit 223 corresponds to the cell transfer speed. A destination address (VPI / VCI) and a transfer mode are set, and an address for a destination buffer is set in the cell generation circuit 222.

FIG. 8 shows the structure of a transfer management table provided in the cell transfer control unit 223. The cell transfer management table stores the presence / absence of a transfer request for the supported transfer speed, transfer mode information, and a destination address for each of the destination buffers 221-1 to 221-128. The transfer management table illustrated in FIG. 8 is an example in the case where the number of destinations is 128 and the supported transfer speeds are 10 types. The transfer timing generation circuits 227 to 228 activate the cell transfer at the transfer speed set from the clock from the ATM / high-speed digital dedicated line I / F control unit 23 and activate the cell transfer control unit 2.
Call 23. The cell transfer control circuit 223 determines the transfer speed based on which of the transfer timing generation circuits 227 to 228 is activated, and activates the cell generation circuit 222 from the speed item of the corresponding transfer management table in accordance with the priority shown in FIG. multiply. The priority of each transfer mode is CBR transfer mode, VBR transfer mode, ABR transfer mode, and UBR transfer mode in order of priority.
In the UBR transfer mode, the presence or absence of a UBR transfer request is checked when there is no request in each transfer mode, and the UBR data cell transfer is activated when there is a UBR transfer request.

For example, a transfer timing generation circuit (1) 2
27, the transfer timing is 64 Kb / s transfer timing, and the cell transfer control unit 223 determines in FIG.
Of the 64 Kb / s item in the transfer management table in the CBR transfer mode, and if there is a request, the destination address and the transfer mode information are stored in the cell generation circuit 22.
Transfer to 2. If there is no transfer request in the CBR transfer mode, the UBR is searched for a transfer request, and if there is a request, the destination address and the transfer mode information are transferred to the cell generation circuit 222. If neither transfer request exists,
“Transfer non-request information” is transferred to the cell generation circuit 222. Since the UBR transfer mode is not limited by the transfer speed, the cell transfer control unit 223 manages to which destination a transfer request has occurred separately from the transfer management table of FIG.
Next, from the 64 Kb / s item of the transfer management table,
It searches for a transfer request in the R transfer mode, and if there is a transfer request in the VBR transfer mode, transfers the destination address and transfer mode information to the cell generation circuit 222. As in the case of the CBR transfer mode, if there is no transfer request in the VBR transfer mode, the UBR is searched for a transfer request, and if there is a request, the destination address and the transfer mode information are transmitted to the cell generation circuit 222. To transfer. Next, the same processing is performed for the ABR transfer mode. Cell generation circuit 222
Transfers the transfer data for one cell from the destination-specific buffer (1) 221-1 to the destination-specific buffer (128) 221-128 based on the transfer start information from the cell transfer control unit 223, and based on the transfer start information, And SAR
Data format 3 (B), 4
(B), and transfer to the ATM / high-speed digital dedicated line I / F control unit 23.

Therefore, a means for registering the transfer mode, transfer speed peak rate, and transfer guarantee speed for each transfer destination is provided, and this information is used to ensure that the bandwidth can be secured even when all information transfer requests occur simultaneously. By calculating and permitting registration, transfer bandwidth is guaranteed.
Using a transfer management table storing transfer request information and transfer mode information corresponding to the transfer peak speed, the cell transmission priority determining means can provide a transfer opportunity even in the UBR transfer mode, which is a transfer mode without bandwidth guarantee.

[0027]

As described above, according to the present invention, a certain amount or more of data is stored in the data buffer by monitoring the amount of data stored in the data buffer 255 of the terminal device control units 24 and 25. Means for sending a data transmission stop command to the communication terminal device by means for restricting the inflow of data from the communication terminal device, and transferring the data stored in the data buffer of the terminal device control unit to the cell conversion control unit. When a certain amount of empty space is created in the data buffer in the terminal device control unit due to the data transfer, means for monitoring the amount of data stored in the data buffer in the terminal device control unit and the restriction of the inflow of data from the communication terminal device Means for allowing the inflow of data from the communication terminal device and accepting the data again. The cell transfer means converts the data transferred to the cell conversion control section into cells, multiplexes the cells, and converts the data into B-ISDN.
The cell is multiplexed by the ATM / high-speed digital leased line interface control unit by means of data transmission to the network or high-speed digital leased line and data is transmitted to the B-ISDN network or high-speed digital leased line. Communication without discarding data can be realized while using almost 100% of the transmission capacity of the line.

Means for setting a transfer mode, a transfer speed peak rate, and a transfer guarantee speed for each transfer destination;
A means for calculating and guaranteeing a transfer band from the number of destinations, a transfer mode, and a line transfer speed setting value, and a cell transmission priority determining means using a transfer table for storing transfer request information and transfer mode information corresponding to a transfer peak speed. One cell transmission circuit can perform cell transfer to a plurality of destinations in different transfer modes and transfer speeds.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a system to which a cell multiplexer according to the present invention is applied.

FIG. 2 is a device configuration diagram of a cell multiplexing device according to the present invention.

FIG. 3 is a frame format of a highway bus in the cell multiplexer according to the present invention.

FIG. 4 is a frame format of a terminal device control unit (X.21 IF unit) in the cell multiplexer according to the present invention.

FIG. 5 is a transmission image diagram of cells output from a cell conversion control unit in the cell multiplexer according to the present invention.

FIG. 6 is a circuit configuration diagram of a terminal device control unit in the cell multiplexer according to the present invention.

FIG. 7 is a circuit configuration diagram of a cell conversion control unit in the cell multiplexer according to the present invention.

FIG. 8 is a transfer management table stored in a destination information storage unit.

FIG. 9 is an operation flowchart of a cell transfer control unit.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 System to which cell multiplexing apparatus according to the present invention is applied 2 Cell multiplexing apparatus 21 Overall control unit 22 Cell conversion control unit 221-1 Destination-specific buffer 1 221-2 Destination-specific buffer 2 221-128 Destination-specific buffer 128 222 cells Generation circuit 223 Cell transfer control circuit 224 Destination information storage unit 225 Highway I / F unit 226 Data bus I / F unit 227 Transfer timing generation circuit 1 228 Transfer timing generation circuit 10 23 ATM / high-speed digital dedicated line I / F control unit 24 Terminal device control unit (V.35 I / F unit) 25 Terminal device control unit (X.21 I / F unit) 251 Control unit 252 Terminal device I / F unit 253 SIO 254 Clock generation circuit 255 Buffer 256 Data bus I / F Unit 26 Terminal device control unit (HSD6MI / F unit) 27 Terminal device control Gobe (HSD1.5M, 128kI /
F section) 28 data bus 29 highway bus 3 B-ISDN 6.3M cell relay network 4 high-speed digital leased line 5 communication terminal device 31 CBR transfer band 32 VBR transfer band 33 ABR transfer band

Claims (1)

[Claims] A means for setting a transfer mode, a transfer speed peak rate, and a transfer guarantee speed for each transfer destination; a means for calculating and guaranteeing a transfer band from the number of destinations, a transfer mode, and a line transfer speed set value; A cell multiplexing device that enables cell transfer to a plurality of destinations in different transfer modes and transfer speeds by using a transfer table storing transfer request information and transfer mode information corresponding to a speed and having a cell transmission priority determining unit.