JPH06268675A - Data transmitting system and terminal server device - Google Patents

Abstract

PURPOSE:To simultaneously and optionally transfer information among the various kinds and a lot of terminal equipments such as telephones, facsimiles or data terminals by using the line exchange connection of an N-ISDN network while using the terminal server device. CONSTITUTION:For example, data from a terminal equipment T2 are stored through a terminal interface 52 in a transmission buffer 62, disassembled into cells by a cell disassembly part 8 within a range suitable for ATM transfer, stored in a cell queue 9, multiplexed by a cell multiplexing part 10 later and transmitted from a transmission part 3 through a line connector 2 to an N-ISDN network N as a first cell multiplex signal. A second cell multiplex signal from the opposite side is received through the line connector 2 by a reception part 4 and stored in a cell reception buffer 11. A cell assembly part 12 discriminates to which terminal equipment the data should by sent by using a routing table 13, and the data are outputted from the correspondent reception buffer through the terminal interface to the terminal equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system and a terminal server device, and more particularly to a telephone connected to an N-ISDN (narrow band digital transmission) network and using a circuit switching connection or a dedicated line. facsimile,
The present invention relates to a data transmission system and a terminal server device that efficiently transmit various types of information such as still images and data.

[0002]

PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION N-
The ISDN network has a feature that, when a single channel is used for circuit switching, a signal from one information source can be transferred among various kinds of information such as telephone, facsimile, still image and data. Information such as data terminals can also be transmitted by packet switching. In this case, it can be applied to transfer a small amount of data via a packet switching network, but it is not economical to transfer a large amount of data. There is a drawback that. Moreover, telephones, facsimiles, and a lot of data are transferred by circuit switching. In this case, once the terminals are connected, even if the signal is not transferred, the other terminals are connected until the line is disconnected. Has the drawback that it cannot interrupt.

Therefore, the main object of the present invention is N
-By using ISDN circuit-switched connections or leased lines, various types of telephones, facsimiles, data terminals, etc.
An object of the present invention is to provide a data transmission method and a terminal server device that enable simultaneous and occasional transfer of information between a large number of terminal devices and can realize information transfer efficiently.

[0004]

The invention according to claim 1 is
It is a data transmission method that uses a narrow band digital transmission network for circuit switching or bidirectionally transmits a signal using a dedicated line.A narrow band digital transmission network or a dedicated line is connected to a plurality of terminal devices, respectively. Connected to each terminal server device, each terminal server device
A transmission signal from each terminal device is decomposed into cells by an asynchronous transfer mode and multiplexed, and transmitted as a first cell multiplexing signal to the terminal server device on the partner side, and a second cell multiplexing is performed from the terminal server device on the partner side. In response to the signal being sent, cells are assembled, data is organized for each terminal device, and the data is supplied to the corresponding terminal device, so that between the terminal devices connected to each terminal server device. Simultaneous data transfer.

The invention according to claim 2 has line connection means for performing line switching connection and disconnection with respect to a narrow band digital transmission network, and is connected with a partner terminal server device connected to a large number of terminal devices. A terminal server device that transmits and receives signals in the state of being circuit-switched and connected by a narrow-band digital transmission network, or that transmits and receives signals in the state of being connected to the terminal server device of the partner side by a dedicated line, A transmission / reception means for transmitting and receiving signals in the terminal device, a transmission buffer provided corresponding to the terminal device and receiving a signal from the corresponding terminal device, and a transmission signal from the corresponding terminal device accommodated in the transmission buffer in the asynchronous transfer mode. Cell disassembling means for disassembling into information units suitable for transfer and disassembling into cells to which headers, which are information parts necessary for information transfer management, are added A cell multiplexing means for time-sequentially multiplexing the cells disassembled by the cell disassembling means and outputting them to the transmitting / receiving means as a first cell multiplexed signal; Cell assembling means for assembling cells of the second cell multiplexed signal according to the identifier included in the second cell multiplexed signal and outputting a received signal corresponding to each terminal device to the corresponding terminal device. To be done.

The invention according to claim 3 provides a terminal interface provided corresponding to each terminal device, for transmitting and receiving a signal to and from the corresponding terminal device, and outputting the signal from the terminal device to a transmission buffer. It is configured to include.

The invention according to claim 4 includes a cell queue for accumulating the cells disassembled by the cell disassembling means.

The invention according to claim 5 includes a receiving buffer for accumulating a signal received by the transmitting / receiving means.

In the invention according to claim 6, the cell assembling means includes a reception buffer for accumulating the assembled cells.

In the invention according to claim 7, the line connecting means monitors the traffic amount from the terminal device and dynamically allocates the channel of the narrow band digital transmission network connected by the circuit switching connection according to the traffic amount. .

[0011]

According to a first aspect of the present invention, each terminal server device connected to a narrow band digital transmission network or a dedicated line multiplexes a transmission signal from each terminal device by cell decomposition in an asynchronous transfer mode and multiplexing. It is transmitted as a cell multiplexing signal to the other terminal server device, and a cell is assembled in response to the second cell multiplexing signal sent from the other terminal server device, and data is prepared for each terminal device. By organizing and supplying to corresponding terminal devices, data transmission between a plurality of terminal devices connected to each terminal server device is performed simultaneously.

In the invention according to claim 2, the signal from the terminal device is accommodated in the transmission buffer, and the accommodated transmission signal is decomposed into information units suitable for transfer in the asynchronous transfer mode,
Disassemble into cells to which a header, which is an information part necessary for information transfer management, is added, and the decomposed cells are time-sequentially multiplexed,
The first cell multiplexed signal is transmitted from the transmitting / receiving means to the narrow band digital transmission network. When the second cell multiplexed signal is sent from the other side via the narrow band digital transmission network, the signal is received by the transmitting / receiving means, cells are assembled according to the identifier included in the signal, and the corresponding terminal is provided. Output to the device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1A is a diagram showing the overall construction of an embodiment of the present invention. The embodiment shown in FIG. 1A is
The N-ISDN network N is used to transfer data between various terminal devices. In FIG. 1A, DSUs are connected to both ends of the N-ISDN network N, and terminal server devices 1a and 1b are connected to each DSU. Each terminal server device 1a, 1b has a terminal device T1a, T2a ... Tna and T, respectively.
1b, T2b ... Tnb are connected. The two terminal server devices 1a and 1b are line-connected by the line switching network N of the N-ISDN network, and in that state, the terminal device T1
a, T2a ... Tna and terminal devices T1b, T2b ... Tnb
Enables data transfer between and including voice.

FIG. 1 (b) is a diagram showing the overall construction of another embodiment of the present invention. This embodiment is the same as the embodiment of FIG. 1A except that the terminal server devices 1a and 1b are connected by a dedicated line S, and the terminal devices T1a, T2a, ... Data transfer is performed between Tna and the terminal devices T1b, T2b, ... Tnb.

FIG. 2 is a specific block diagram of the terminal server device shown in FIG. In FIG. 2, the terminal server device 1 includes terminal interfaces 51, 52 ... 5n to which the terminal devices T1, T2 ... Tn are connected. Furthermore, the terminal server device 1 has a terminal interface 5
Transmission buffers 6 connected to 1, 52, ...
6n and reception buffers 71, 72 ... 7n,
6n connected to the transmission buffers 61, 62 ... 6n, a cell queue 9 connected to the cell decomposition unit 8, a cell multiplexing unit 10 connected to the cell queue 9, and a transmission unit 3
, Line connection device 2, receiving unit 4, cell receiving buffer 11, cell assembling unit 12, and routing table 13
Including and

Next, the operation of the terminal server device 1 will be described. With the line connection device 2, N
-Connected by a circuit switching connection of the ISDN network N, and the transmitting unit 3 and the receiving unit 4 deliver a cell multiplexed signal, which will be described later, to a partner device. That is, the terminal server device 1
The transmission signals from the n terminal devices T1, T2 ... Tn connected to the respective terminal interfaces 51, 52, ...
n is received and stored in the corresponding transmission buffers 61, 62 ... 6n. The cell disassembling unit 8 includes the terminal devices T1, T2 ... T.
6n are accessed at a rate according to the type of data from n, the data rate, etc., and the asynchronous transfer mode (ATM: asynchronous tr) is accessed.
The cell is decomposed into cells having a predetermined cell header corresponding to the (transfer mode), and the cells are temporarily stored in the cell queue 9. The transmission signal is divided into certain units and sequentially enters the information field of the cell.

FIG. 3 is a diagram showing the structure of the cell. As shown in FIG. 3A, the cell structure is composed of a 5-octet cell header 21 and a 48-octet information field 22. Then, as shown in FIG. 3B, the cell header includes the virtual channel identifier VCI, the virtual path identifier VPI, and the like. The cell multiplexing unit 10 uses the cell queue 9
By reading the cells stored in
The signals are multiplexed in time series and output to the transmitter 3 as a first cell multiplexed signal to be transmitted to the other party. The transmitter 3 is the first
Cell multiplexed signal of N-IS via the line connection device 2.
It is transmitted to the DN network N.

On the other hand, the second sent from the device on the other side
The cell-multiplexed signal of is received by the receiving unit 4 via the line connection device 2.
Are received in the cell reception buffer 11 and are temporarily stored in the cell reception buffer 11.
The cell assembling unit 12 sequentially reads cells from the cell reception buffer 11, determines the terminal device to be received from the virtual channel identifier VCI of the cell header, and receives the reception buffers 71,
Send the information field of the cell to the corresponding receiving buffer of 72 ... 7n. For example, in the case of information to the terminal device T2, the information field is sent to the reception buffer 72.

The cell assembling unit 12 can specify the address of the routing table 13 by the virtual channel identifier VCI and easily determine the terminal to receive.

The information fields sequentially accumulated in the reception buffers 71, 72 ... 7n are the terminal interfaces 51, 5
Each of the terminal devices T1, T as a reception signal via 2 ... 5n.
2 ... Sent to Tn.

As described above, the terminal server device 1
a, 1b, and by connecting the lines using one line of the N-ISDN network N, each terminal server device 1a,
Various terminal devices T1a, T2a ... Tan connected to 1b
, And data transfer between T1b, T2b ... Tnb can be realized simultaneously and bidirectionally.

In this case, the terminal server device 1
The case where the connection between a and 1b is made by the circuit switching connection of the N-ISDN network N has been described, but the terminal server device 1
It is also possible to connect between a and 1b with a dedicated line.

Further, the terminal server devices 1a and 1b according to the embodiment of the present invention are circuit-switched NI.
The channels of the SDN network N can be dynamically assigned according to the amount of traffic. That is, the line connection device 2
Is a terminal device T connected to the terminal server device 1.
The required traffic amount is calculated according to the type of 1, T2 ... Tn, and the channel of the N-ISDN network N is connected based on this. For example, the traffic volume is 64 kbp
When s or less, one B channel line is connected, and when the traffic volume is about 100 kbs, two B channel lines are connected. In a typical circuit-switched connection, a B-channel of an N-ISDN network N is directly connected to a device on the other side at the time of circuit switching. On the B-channel, a sender is an X25 DTE and a receiver is an X25 DCE protocol. To execute.

In the above embodiment, the cell structure is B-ISDN (broadband ISDN) compatible with ATM.
Although the standard cell of FIG. 3 (FIGS. 3A and 3B) was used, the ratio of the overhead to the data to be transferred is large and the efficiency becomes poor. Therefore, the cell header has 5 octets like the cell header of the standard cell, and when the amount of information data is large, the information field can be increased to reduce the overhead ratio. For example, in FIG.
As shown in (c), the information field can be n octets (n <2 ^m −5). In this way, the size of the information field can be made variable according to the type of information data, and the transfer efficiency can be improved.

Regarding the cell header, the above-mentioned B-
The virtual channel identifier VC is not limited to the ISDN standard cell.
It goes without saying that any information including information necessary for cell transfer management such as I and virtual identifier VPI may be included.

[0026]

As described above, according to the present invention, it is possible to connect the two terminal server devices, to which a large number of various data terminals are connected, to the circuit-switched connection of the N-ISDN network or to connect to the dedicated line. As a result, data transfer between these data terminal devices can be performed simultaneously, and efficient data transfer can be realized.

[Brief description of drawings]

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

FIG. 2 is a schematic block diagram of a terminal server device according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a cell structure.

[Explanation of symbols]

 1, 1a, 1b Terminal server device 2 Line connection device 3 Transmission unit 4 Reception unit 8 Cell disassembly unit 9 Cell queue 10 Cell multiplexing unit 11 Cell reception buffer 12 Cell assembly unit 13 Routing table 51, 52 ... 5n Terminal interface 61, 62 ... 6n transmission buffer 71, 72 ... 7n reception buffer T1, T2 ... Tn terminal device T1a, T2a ... Tna terminal device T1b, T2b ... Tnb terminal device

Claims (7)

[Claims] 1. A data transmission system for bidirectionally transmitting a signal by using a narrow band digital transmission network by circuit switching or by using a dedicated line, wherein each of the narrow band digital transmission network and the dedicated line is plural. Is connected to the terminal server device to which the terminal device is connected, and each of the terminal server devices performs cell decomposition of the transmission signal from each terminal device in an asynchronous transfer mode to multiplex, and outputs the signal as a first cell multiplexed signal. It is transmitted to the terminal server device of the other party, and the cell is assembled according to the second cell multiplexing signal sent from the terminal server device of the other party, and the data is organized for each terminal device to correspond to it. By supplying the data to the terminal devices, it is possible to simultaneously perform data transmission between a plurality of terminal devices connected to the terminal server devices. And wherein the the data transmission method. 2. A narrow band digital transmission network having line connection means for performing line switching connection and disconnection with respect to the narrow band digital transmission network, and with a partner terminal server device connected to a large number of terminal devices. A terminal server device that sends and receives signals in the state of being circuit-switched and connected or that sends and receives signals in the state of being connected to the partner terminal server device by a dedicated line, and that sends and receives signals to and from the partner device. Transmission / reception means, a transmission buffer provided corresponding to the terminal device and receiving a signal from the corresponding terminal device, information adapted to transfer a transmission signal from the corresponding terminal device accommodated in the transmission buffer in the asynchronous transfer mode Cell disassembling means for disassembling into units and disassembling into cells to which headers, which are information parts necessary for information transfer management, are added, Cell multiplexing means for time-sequentially multiplexing the cells disassembled by the solving means and outputting to the transmitting / receiving means as a first cell multiplexed signal; and the first device sent from the other party's device via the transmitting / receiving means. The cell of the second cell multiplexed signal is assembled according to the identifier included in the second cell multiplexed signal, and the cell assembly means for outputting the received signal corresponding to each terminal device to the corresponding terminal device is provided.
Terminal server device. 3. A terminal interface provided corresponding to each of the terminal devices, for transmitting / receiving a signal to / from a corresponding terminal device, and outputting a signal from the terminal device to the transmission buffer. The terminal server device according to claim 2. 4. The terminal server device according to claim 2, further comprising a cell queue for accumulating the information decomposed by the cell disassembling means. 5. The terminal server device according to claim 2, further comprising a reception buffer for accumulating a signal received by said transmitting / receiving means. 6. The terminal server device according to claim 2, wherein the cell assembling means includes a reception buffer for accumulating the assembled cells. 7. The line connection means monitors the traffic volume from the terminal device and dynamically allocates a channel of a narrow band digital transmission network connected by a circuit switching connection according to the traffic volume. The terminal server device according to claim 2.