JP2868416B2 - 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 and demultiplexed 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, multiplex information obtained by dividing the multi-frame information into fixed lengths, and a start time of the multiplex information. Means (5) for converting the position information of the slot in the multi-frame into an ATM cell set in an information field and transmitting the ATM cell to an ATM communication network. And butterflies.

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 for extracting (7), means for identifying the position information in the multiframe of the first time slot of the multiplex information from the information set in the information field, and means for restoring the information of the multiframe (8); It is desirable to provide means (9, 10) for decomposing the multi-frame information and transmitting the multi-frame information to a plurality of receiving terminals. Provided,
If there is no significant data in the multiplexed information obtained by dividing the multi-frame information into fixed lengths,
It is desirable to include means for inhibiting transmission to the TM communication network.

[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 first CLAD unit converts the multiplexed information obtained by dividing the multiplexed multi-frame information into fixed lengths, and the position information of the first time slot of the multiplexed information in the multi-frame into an ATM cell as an ATM cell information field. Then, the data is sequentially transmitted to the ATM communication network. The ATM communication network uses this A
The ATM cell is exchanged by VPI / VCI in the header of the TM cell, and the second CLAD unit transmits the A from the ATM communication network.
Upon receiving the TM cell, the multi-frame information is restored from the multiplex information of the information field of the ATM cell and the position information of the first time slot of the multiplex information in the multi-frame. The multiplexed information is separated and isochronous data is sent 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; First, multiplexed information obtained by dividing frame information into fixed lengths and position information of the first time slot of the multiplexed information in the multiframe are converted into ATM cells set in information fields and transmitted to an ATM communication network. The first CLAD unit 4 including an ATM interface 5 and performing time division multiplexing is provided for each of the plurality of transmission terminals 1. Further, a second ATM interface 7 for receiving an ATM cell of a multi-frame coming from the ATM communication network 6 and taking out its information field, and, based on the information set in the information field, a second ATM interface 7 in the first time slot of the multiplexed information A second CLAD unit 8 for identifying position information and restoring the information of the multi-frame, a second time-division multiplexing / demultiplexing bus 9 for decomposing the restored multi-frame information and transmitting it to a plurality of receiving terminals 11; 10 is 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 ( Q 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 includes multiplex position information and multiplex 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 and the position information {F (Y), TS (X)} in the multiframe of the first time slot of the multiplexed information are used as ATM cell information fields, and the VPI It is converted to an ATM cell to which a header including / VCI is added. The sequentially converted ATM cells are sent to the AT via the first ATM interface 5.
It is sent to the M communication network 6.

The ATM communication network 6 exchanges ATM cells according to VPI / VCI in the header of the ATM cells. ATM
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 first time slot of the multiplex information in the multi-frame, and converts the multi-frame information into the second time-division multiplex / demultiplex bus 9. Output to 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.

(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 a fixed length, and uses the divided multiplexed information and the position information {F (Y), TS (X)} in the multiframe of the first time slot of the multiplexed information as an information field of the ATM cell. It is converted to an ATM cell to which a header including / 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 interface 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.

[0027]

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 (1)

(57) [Claims] The transmitting side transmits an isochronous digital signal coming from a plurality of transmitting terminals to one transmitting terminal.
One time-division multiplexing means for performing time-division multiplexing on information of a multiframe composed of P (P is a natural number) time slots and one multiframe composed of Q (Q is a natural number) frames; one for transmitting and converting the information of the frame into ATM cells set the position information to the information field in the multi-frame multiplex information obtained by separating the fixed length and the head time slot of the multiplex information in the ATM communication network
One of the means and the multiframe information into multiple information obtained by separating the fixed length, when there is no significant data in the multiple information A
Means for prohibiting transmission to the TM communication network; means for receiving, on the receiving side, a multi-frame ATM cell arriving from the ATM communication network and extracting its information field; and information set in the information field. And a restoring means for recognizing position information in a multiframe of a leading time slot of the multiplexed information and restoring the information of the multiframe and transmitting the information to a plurality of receiving terminals. .