JP2730488B2 - ATM cell transfer method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for transferring isochronous data in ATM (Asynchronous Transfer Mode). The present invention relates to an isochronous data ATM cell transfer method capable of eliminating cell conversion and decell processing for each terminal, reducing the number of cell conversion buffer memories, and reducing delay time due to cell conversion.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a configuration of a conventional example.
FIG. 4 is a diagram showing a format of an ATM cell and isochronous data in a conventional example.

In the conventional system configured as described above, when isochronous data is converted into fixed-length ATM cells and asynchronous transfer is performed, when the transmitting side is the terminal 1, the terminal 1 corresponds to the terminal 1. The arranged first CLAD unit (cell assembling / disassembling circuit) 14 receives the isochronous data transmitted via the interface 2 and converts it into an ATM cell as shown in FIG.
This is time-division multiplexed by the first temporary multiplexing / demultiplexing bus 13,
ATM communication network 1 via first ATM interface 15
6 had been sent.

[0004] The ATM communication network 16 transmits the transmitted A
ATM cells are exchanged by VPI (virtual path identifier) and VCI (virtual channel identifier) in the header of the TM cell, and the second C
To the LAD unit 18 and the second CLAD unit 18
The M cell is received, decellulated, and transmitted as isochronous data to the terminal 11 on the receiving side via the interface 10. When multiplexing and transferring isochronous data from a plurality of terminals 1 on the transmission side, isochronous data from each terminal 1 is converted into an ATM cell, and then multiplexed / separated on a cell basis to perform isochronous data. The data was transferred as ATM cells.

A method for assembling and transferring a plurality of pieces of information as one cell to an asynchronous transfer network is disclosed in Japanese Patent Laid-Open Publication No. 2-58945. And does not use a multi-frame format to allocate in a matrix in the X and Y directions.

[0006]

As described above, according to the conventional method, when a plurality of isochronous data are transferred, the isochronous data from each terminal is converted into an ATM cell.
CLAD (= Cell Assembly De) for each terminal interface
assembly: a cell assembling / disassembling circuit) and a buffer memory for cell conversion had to be provided for each terminal interface. In addition, in the case of low-speed data, there is a disadvantage that the delay time becomes large when the cell is formed.

The present invention solves such a problem, and reduces the number of CLAD units and buffer memories for cell conversion, and suppresses an increase in delay time due to cellization of low-speed data. It is an object of the present invention to provide an ATM cell transfer method.

[0008]

SUMMARY OF THE INVENTION The present invention eliminates cellization and decellulation processing for each terminal in isochronous data transfer in which isochronous data is converted into fixed-length ATM cells and asynchronously transferred. In order to reduce the number of cell conversion buffer memories and reduce the delay time, an isochronous digital signal arriving from a plurality of transmitting terminals is composed of P (P is a natural number) time slots. Means (4) for time-division multiplexing one multi-frame into multi-frame information composed of Q frames, and setting, in an information field, multiplex information obtained by dividing the multi-frame information into fixed lengths, The position information of the first time slot of the information in the multi-frame is converted into an ATM cell set in a VCI (virtual channel identifier) in an ATM cell header. Characterized in that a means (5) to be transmitted to the ATM communication network Te. That is, the feature is that the position information of the first time slot of the multiplex information in the multi-frame is not set in the VPI (virtual path identifier) in the ATM cell header but is set in the VCI (virtual channel identifier).

The time-division multiplexing means (4) is provided once for each of the plurality of transmitting terminals, and further receives an ATM cell of a multi-frame coming from the ATM communication network (6) and converts its information field. Means (7) for extracting the position information of the first time slot of the multiplex information in the multiframe from the VCI set in the header and restoring the information of the multiframe (8)
And means (9, 10) for decomposing the restored multi-frame information and transmitting the decomposed multi-frame information to a plurality of receiving terminals. It is preferable that the multiplex information obtained by dividing the multi-frame information into fixed lengths include means for prohibiting the transmission of the multiplex information to the ATM communication network when there is no significant data. .

[0010]

The first temporary division multiplexing / demultiplexing bus includes isochronous data from a plurality of transmitting terminals. One frame is composed of P ( P is a natural number ) time slots, and one multiframe is Q ( Q
Is a natural number ) frames, time-division multiplexed,
The multiplexed information obtained by dividing the multiplexed multi-frame information in the first CLAD section into fixed lengths is used as an information field of the ATM cell, and the position information of the first time slot of the multiplexed information in the multi-frame is set as VCI in the header. The data is converted into ATM cells and transmitted to the ATM communication network sequentially. A
The TM communication network uses VPI / VC in the header of this ATM cell.
The ATM cell is exchanged by I, and the second CLAD unit
Receiving the ATM cell from the TM communication network, and restoring the multi-frame information from the multiplex information of the information field of the ATM cell and the position information in the multi-frame of the first time slot of the multiplex information indicated by the VCI in the header; A two-time division multiplexing / demultiplexing bus separates the information multiplexed in the multiframe and sends out isochronous data to the receiving terminal.

[0011] After isochronous data from a plurality of transmitting terminals is time-division multiplexed and the multiplexed multi-frame information is converted into ATM cells, even if the number of terminals increases, the CLAD unit and An increase in the number of cell conversion buffers can be suppressed, and an increase in delay time that occurs when low-speed data is converted into cells can be prevented.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention, and FIG. 2 shows a configuration of an ATM cell format and a configuration of a multi-frame format in the first embodiment of the present invention. FIG.

In the first embodiment of the present invention, the interface 2 and the first temporary division multiplex
The isochronous digital signal arriving via the separation bus 3 is
A first CLAD unit (cell assembling / disassembling circuit) 4 in which a frame is composed of P time slots (P is a natural number) and one multi-frame is time-division multiplexed into information of a multi-frame composed of Q frames; Multiplex information obtained by dividing the frame information into fixed lengths is set in the information field, and the position information of the first time slot of the multiple information in the multiframe is represented by V in the ATM cell header.
A first ATM interface 5 for converting ATM cells set to VCI (virtual channel identifier) instead of PI (virtual channel identifier) and transmitting the ATM cells to the ATM communication network; One transmission terminal 1 is provided.

Further, a second ATM interface 7 for receiving a multi-frame ATM cell arriving from the ATM communication network 6 and taking out its information field, and a VCI set in the header of the second ATM interface 7, A second CLAD unit 8 for identifying position information in a multi-frame and restoring the multi-frame information;
A second time-division multiplexing / demultiplexing bus and an interface for decomposing the restored multi-frame information and transmitting it to a plurality of receiving terminals are provided. One second CLAD unit 8 for restoring the multi-frame information is provided for each of the plurality of receiving terminals 11, and if there is no significant data in the multiplex information obtained by dividing the multi-frame information into fixed lengths, Means for inhibiting transmission of multiplexed information to the ATM communication network 6 is included.

As shown in FIG. 2, the multi-frame format is configured by arranging Q (P is a natural number) frames composed of P (P is a natural number) time slots. An ATM cell is composed of a header and an information field, and the header includes VPI / VCI.
The information field is <br/> includes multiple position information and multiplexing information. The multiplex position information is information indicating positions F (Y) and TS (X) where the multiplex information is stored in the multi-frame format. Is information indicating the number of the item.

Here, the operation of the first embodiment of the present invention configured as described above will be described.

The isochronous data from the terminal 1 of a plurality of transmitting side is sent to the first time-division multiplexing and demultiplexing bus 3 via the respective interface 2, as shown in FIG. 2, one frame P (P Is a natural number ) time slots and time-division multiplexed such that one multiframe is composed of Q ( Q is a natural number ) frames.

The multiplexed multi-frame information is the first C
The multiplexed information divided into fixed lengths by the LAD unit 4 is used as the information field of the ATM cell, and the position information ΔF of the first time slot of the multiplexed information in the multiframe is used.
(Y), TS (X)} as VCI in the header, VP
It is converted into an ATM cell to which a header including I / VCI is added. The sequentially converted ATM cells are transmitted to the ATM communication network 6 via the first ATM interface 5.

The ATM cell communication network 6 exchanges ATM cells according to VPI / VCI in the header of the ATM cells. A
ATM cells transmitted from the TM communication network 6 are input to the second CLAD unit 8 via the second ATM interface 7. The second CLAD unit 8 restores the multi-frame information from the multiplex information in the information field of the ATM cell and the position information in the multi-frame of the first time slot of the multiplex information indicated by the VCI in the header, and Output to the time division multiplexing / demultiplexing bus 9. Each interface unit 10 connected to the second time-division multiplexing / demultiplexing bus 9 separates information multiplexed into multi-frames on the second time-division multiplexing / demultiplexing bus 9 and outputs isochronous data on the receiving side. Send it to terminal 11.

Since the position information {F (Y), TS (X)} is directly used as VCI (not VPI), no problem occurs in the ATM communication network 6 in terms of switching connection. ATM cell to send and AT to receive
For the M cell, the assembly and disassembly of the cell can be executed with reference to the VCI table.

(Second Embodiment) A second embodiment of the present invention is shown in FIG.
The first CLAD unit 4 is configured similarly to the first embodiment shown in FIG.
When the multiplexed information has no significant data and the multiplexed information area is not used, the ATM of the corresponding ATM cell is used.
Means for prohibiting transmission to the communication network 6 and transmitting a corresponding ATM cell to the ATM communication network 6 when the multiplexed information contains significant data and a multiplexed information area is used.

In the second embodiment of the present invention thus constituted, isochronous data from a plurality of transmitting terminals 1 is transmitted to a first multiplexing / demultiplexing bus 3 via respective interfaces 2, Here, one frame is P ( P is a natural number )
Consists of time slots and one multiframe is Q
It is time-division multiplexed into a multiframe composed of ( Q is a natural number ) frames.

The multiplexed multi-frame information is the first C
The LAD unit 4 divides the multiplexed information into fixed lengths and uses the multiplexed information as an information field of an ATM cell. As the VCI within
It is converted into an ATM cell to which a header including VPI / VCI is added.

When the multiplexed information obtained by dividing the multiplexed multi-frame information into fixed lengths has no significant data, that is, when the multiplexed information area is not used, the first CLAD unit 4 When the corresponding ATM cell is not converted (not generated) and significant data is included in the multiplexed information obtained by dividing the multiplexed multiframe information into fixed lengths, that is, when the multiplexed information area is used. The ATM cell corresponding to the multiplexed information is converted and generated, and the sequentially converted and generated ATM cell is transmitted to the ATM communication network 6 via the first ATM interface 5.

The ATM communication network 6 exchanges ATM cells according to VPI / VCI in the header of the ATM cells,
The ATM cells transmitted from the communication network 6 are input to the second CLAD unit 8 via the second ATM interface 7. The second CLAD unit 8 restores the multi-frame information from the multiplex information of the information field of the ATM cell and the position information of the head time slot of the multiplex information in the multi-frame, and divides the multi-frame information into the second time-division multiplexing / demultiplexing. Output to the bus 9.

Each of the interfaces 10 connected to the second time division multiplexing / demultiplexing bus 9 separates information multiplexed into multi-frames on the second time division multiplexing / demultiplexing bus 9 and transmits isochronous data to the receiving side. To the terminal 11.

In the second embodiment, even if there is an ATM cell which is prohibited from being transmitted because it does not include significance data, the portion becomes blank in the multi-frame information restored on the receiving side. Further, by prohibiting the transmission, the traffic of the ATM communication network can be made economical.

[0029]

As described above, according to the present invention, the multiplexed multi-frame information is converted to ATM cells after time-division multiplexing of isochronous data from a plurality of transmitting terminals. In addition, even if the number of terminals increases, an increase in the number of CLAD units and cell conversion buffer memories can be suppressed, and further, an increase in delay time that occurs when low-speed data is converted into cells can be suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment and a second embodiment of the present invention.

FIG. 2 shows A in the first embodiment and the second embodiment of the present invention.
The figure which shows the format of a TM cell, and the format of a multi-frame.

FIG. 3 is a block diagram showing a configuration of a conventional example.

FIG. 4 is a diagram showing a format of an ATM cell and isochronous data in a conventional example.

[Explanation of symbols]

 1,11 Terminal 2,10 Interface 3,13 First Temporary Division Multiplexing / Demultiplexing Bus 4,14 First CLAD Unit 5,15 First ATM Interface 6,16 ATM Communication Network 7,17 Second ATM Interface 8,18 Two CLAD units 9, 19 Second time division multiplexing / demultiplexing bus

Claims (4)

(57) [Claims] 1. A transmitting side includes : a frame for isochronous data signals arriving from a plurality of transmitting terminals , wherein each frame is composed of P (P is a natural number) time slots;
Means for time-division multiplexed in the frame multiframe information consists of one multiframe Q pieces (Q is a natural number), the solid obtained by separating the multi-frame information in fixed length
The fixed length data is loaded in the information field of the ATM cell ,
The position information (F (Y), TS (X)) of the first time slot of the fixed-length data of the
Means for converting the ATM cell into an ATM cell mounted in a VCI (virtual channel identification signal) area of the M cell header and transmitting the ATM cell to the ATM communication network . The receiving side receives the multi-frame information coming from the ATM communication network.
The received ATM cell is received and its information field is
From the VCI set in the ATM cell header.
In the multiframe of the first time slot of
The time-division multiplexing on the transmitting side by identifying location information
Means for restoring multi-frame information . 2. A restored ATM cell transfer method of decomposing multiframe information according to claim 1, further comprising means for transmitting to a plurality of receiving terminals. 3. The ATM cell transfer system according to claim 2 , wherein one means for restoring the multi-frame information is provided for a plurality of receiving terminals. 4. A system according to claim 1, further comprising means for prohibiting transmission of said fixed-length data to an ATM communication network when said fixed-length data obtained by dividing said multi-frame information into fixed lengths has no significant data. ATM according to any one of 3.
Cell transfer method.