JPH05268256A - Adding information transmission system in atm - Google Patents

Abstract

PURPOSE:To improve multiplexing efficiency by storing communication control information controlling ATM communication to be communicated between ATM exchanges in a surplus area and transmitting it in the case when a generated ATM cell has the surplus area. CONSTITUTION:When a cell control means 1 receives data from LAN or a computer, a communication control information detection part 5 detects control information or communication from the pertinent data. A cell generating part 6 generates the ATM cell by dividing the pertinent data into data of fixed-length and adding an ATM header to each of them. A control part 4 discriminates whether the ATM cell has the surplus area or not and when it has, communication control information detected by the detection part 5 is stored in the surplus area and transferred to the ATM exchange 2. A cell resolving part 7 removes the ATM header from the ATM cell and combines fixed-length data from which the ATM header is removed so as to restore the pertinent LAN data or computer data. Thus, the congestion of the exchange 2 can be surpressed to minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention converts information such as LAN data and computer data into fixed-length packets called cells, which are accommodated in an asynchronous communication (ATM) network to provide a plurality of LANs.
The present invention relates to a method for exchanging information by using an excess area in a cell in an ATM network that interconnects computers and computers.

[0002]

2. Description of the Related Art Recently, research and development of a broadband ISDN has been promoted as a next-generation communication network that integrates all communication services such as voice, data and moving images.

Among them, in order to speed up the digital transmission system, the STM (Synchronou
ATM (Asynchronous Transfer Mode) has been discussed in CCITT as an alternative to s Transfer Mode.

ATM is a method of transferring information in cells which are fixed length packets, and the cells are 48
It is a 53-byte packet consisting of an octet information field and a 5-octet header part. 53
Bytes are currently defined by international standards.

Here, the above-mentioned ATM header is No. 5
The first 4 bits of the byte are the generic flow control GFC used for flow control between links,
The next 8 bits are the virtual path control identifier VPI, the next 16 bits are the virtual channel identifier VCI, the next 2 bits are the payload type PT indicating the cell type, the next 1 bit is reserved, and the next 1 bit is the time of congestion. Cell priority PR used to control cell discard, last 8 bits are A
It is composed of a header error control HEC for 1-bit error correction and 2-bit error detection in the TM header.

On the other hand, in the information field, LAN (LOCA
Stores data that is sent and received in L AREA NETWORK) communication, large computer communication, etc., with a header and trailer added.

Here, in the case of converting LAN data or large-scale computer data into ATM cells, variable-length LAN data or large-scale computer data is divided into information field lengths of ATM cells and stored in a plurality of ATM cells. Will be done. Further, as described above, since the information field is composed of divided data, a header to be added to it, and a trailer, the divided data storage area is a 44-byte area excluding the 4 bytes of the header and 4 bytes of the trailer. Will be assigned. That is, variable-length data is divided into 44-byte units, a header and a trailer are added to each, and this is stored in the information field of the ATM cell and transferred.

The header is a segment type ST2 bit indicating the position of the cell when the data is divided,
It is cyclically added to cells in units of level 3 protocol data units, and consists of a sequence number SN4 bits for detecting discarding in units of cells and a reserved 10 bits.

On the other hand, the trailer is composed of a payload length of 6 bits indicating the effective length of the data, and a CRC of 10 bits for cyclic redundancy check code for error correction and detection. In the above-mentioned segment type ST2 bit, when dividing the data, whether the divided data is located at the beginning or in the middle of the data before the division,
A that stores an identifier that identifies whether it was located at the end
A TM cell conversion system is known.

[0010]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the M-cell system, the data length of the LAN or large-scale computer is variable, so the data length of the data is ATM.
It is rare for it to be an integer multiple of 44 bytes, which is the most precious cell information storage, and the ATM cell whose segment type represents the last cell may store data with a data length of less than 44 bytes. Many.

Therefore, there is a free area of 44 (bytes)-(data length) in the information field of the last cell. Conventionally, this empty area is treated as undefined data by the ATM exchange on the transmitting side, and skipped by the ATM exchange on the receiving side. Therefore, there is a problem that the empty area becomes a useless area and the data multiplexing efficiency is reduced.

Therefore, the present invention has been made in view of the above problems, and a plurality of ATMs are provided in the empty area of the final cell.
It is a technical object to provide an ATM cell system that stores information for controlling ATM communication performed between exchanges and improves the multiplexing efficiency of the ATM exchange network.

[0013]

In order to solve the above problems, the present invention is as follows. This will be described based on the principle diagram of FIG.

Asynchronous transfer communication (ATM) in which data transferred between LANs and computers is divided into cell units and transferred.
AT from network data or computer data in the network
Cell control means 1 for generating M cells and restoring LAN data or computer data from ATM cells, and a plurality of ATMs for exchanging ATM cells through a transfer path 3.
It is composed of an exchange 2.

The cell control means 1 includes a cell generation section 6, a cell disassembly section 7, a communication control information detection section 5, and a control section 4.
The cell generation unit 6 divides LAN data or computer data and adds an ATM header to each divided data to generate an ATM cell.

The cell disassembly unit 7 deletes the ATM header from the ATM cell sent from the ATM switch to extract the divided data, and combines the divided data belonging to the same group among these divided data to LAN data or computer data. Is to restore.

The communication control information detecting section 5 detects communication control information from LAN data or computer data and also detects communication control information from ATM cells. The control unit 4 controls the respective units, determines whether or not there is a surplus area in the cell generated by the cell generation unit 6, and if there is a surplus area, the communication is performed in the surplus area. The communication control information detected by the control information detector 5 is stored.

Here, the communication control information is LA
It is possible to use congestion information indicating the congestion states of each of N, computer, and ATM network. Further, it is preferable to store the communication control information when the surplus area of the ATM cell to be transmitted is 3 bytes or more.

Further, when the ATM cell has a surplus area, the error detection code can be stored in the surplus area together with the communication control information. At this time, the AT
In the cell control means 1 on the receiving side that has received the M cells, the control unit 4 performs error detection of the surplus area based on the error detection code stored in the surplus area. If no error is detected, the surplus area is detected. Make sure that the area stores information.

Preferably, the error code is a cyclic redundancy check code (CRC).
Should be used.

[0021]

Therefore, according to the present invention, the cell control means is the LA
When data is received from N or a computer, in the cell control means, the communication control information detection unit detects communication control information from the data and notifies the cell disassembly unit of this.

Upon receipt of the notification, the cell disassembling unit A destined for the LAN or computer that is the source of the data
When the TM cells are disassembled and transferred, it is possible to control the transfer of data restored by disassembling the ATM cells according to this communication control information. As a result, communication that should be performed between the ATM exchange and the LAN or between the ATM exchange and the computer can be efficiently performed.

On the other hand, the cell generation unit divides the data received from the LAN or the computer into fixed-length data, and adds an ATM header to each of them to generate an ATM cell.
Then, the control unit controls the AT generated by the cell generation unit.
It is determined whether or not the M cell has a surplus area, and when the surplus area exists, the state of the ATM switch of the transmitting side, A,
Communication control information indicating the state of the transfer path of the TM switching network is stored and transferred to the ATM switching network.

On the contrary, the cell control means operates from the ATM switching network to the A
When the TM cell is received, the control unit determines whether the ATM cell has a surplus area, and when the ATM cell has a surplus area, whether the communication control information is stored in the surplus area. ..

If the communication control information is stored in the surplus area, the communication control information detecting section detects the communication control information. The detected communication control information is notified to the cell generation unit.

Upon receipt of the notification, the cell generation unit can recognize the state of the ATM switch as the transmission source and the state of the transfer path. That is, after that, the ATM switch is used for AT
It is possible to control the transfer of the ATM cell based on this communication control information when transferring the M cell and when transferring the ATM cell to the ATM switching network. As a result, it is possible to improve the multiplexing efficiency in the ATM switching network.

On the other hand, the cell disassembling unit removes the ATM header from the ATM cell, restores the LAN data or the computer data by combining the fixed length data from which the ATM header has been removed, and restores this at the destination of the data. Transfer to a LAN or computer.

If congestion information is stored in the surplus area of an ATM cell as the communication control information, for example, ATM
Congestion information of exchange, congestion information of ATM switching network, AT
Congestion information of the communication path connecting the M switch and the LAN, LA
In the case of N congestion information, congestion information of a communication path connecting an ATM switch and a computer, etc., first, when it is congestion information of the ATM switch network, when transmitting ATM cells to the ATM switch network. , The AT of the ATM cell based on the congestion information detected from the ATM cell previously received from the ATM switching network.
Controls transmission to the M-switch network. That is, when the ATM switching network is congested, the transmission of ATM cells is delayed,
When the ATM switching network is not congested, it is possible to perform ATM cell generation and transmission to the ATM switching network.

Second, in the case of congestion information of a communication path connecting the ATM exchange and the LAN, congestion information of a communication path connecting the ATM exchange and the computer, or congestion information of the LAN, the LAN or the computer is On the other hand, when the ATM cell is disassembled and the restored data is transferred, the transfer of the restored data can be controlled based on the congestion information detected from the data previously received from the LAN or the computer.
That is, if the communication path with the LAN or the communication path with the computer is congested, the transfer of data is delayed, and if the communication path is not congested, this restoration is performed together with the restoration of the data. Data can be transferred to a LAN or computer.

[0030]

EXAMPLES Specific examples of the present invention will be described below. FIG. 2 is an overall configuration block diagram of a communication system using the ATM cell assembling system of the present invention.

The present system includes a calling side LAN data cell converter 8a, a called side LAN data cell converter 8b, and a calling side ATM switch 9 which are connected to a calling side LAN via a communication path.
a, a destination ATM switch 9b, and a transfer path connecting the originating ATM switch 9a and the destination ATM switch 9b in the ATM network.

The originating LAN data cell conversion device 8a converts the data sent from the originating terminal 10a of the originating LAN into A
This is a device for dividing and converting the ATM cells and transferring the converted ATM cells to the ATM switching network 12. This specific description will be described later.

The originating side ATM exchange 9a and the destination side ATM exchange 9b mutually exchange cells through the transfer path 11. Destination LAN data cell conversion device 8b
Is a device that restores and converts the ATM cells sent from the destination ATM switch 9b into LAN data and transfers the restored data to the destination terminal 10b of the destination LAN.

FIG. 3 is a block diagram of the internal configuration of the LAN data cell conversion device 8 in this embodiment. The LAN data cell conversion device 8 according to this embodiment includes a cell generation unit 1
3, cell disassembly unit 14, information detection unit 15, cell buffer 1
6, a LAN data storage unit 17, a control device 18, and a CRC checker 19.

The cell generation unit 13 in this embodiment is
The LAN data sent from N is divided, and an ATM header is added to each of the divided data to convert it into ATM cells.

The cell disassembling unit 14 deletes the ATM header sent from the ATM switch 9 by synchronizing the ATM header with the ATM header and deletes the ATM header.
The LAN data is restored by combining the divided data belonging to the same group among the divided data stored in the cell.

The information detecting section 15 detects LAN congestion information from the LAN data sent from the LAN, and detects A congestion information from the ATM cell sent from the ATM switch 9.
The congestion information of the TM network or the congestion information of the transfer path 11 is detected.

The cell buffer 16 is for temporarily storing the ATM cell generated by the cell generation unit 13.
The LAN data storage unit 17 is for temporarily storing the LAN data restored by the cell disassembling unit 14.

The CRC checker 19 is an ATM switching network 1
Cyclic redundancy check code (hereinafter CRC; CY) for error correction and detection stored in ATM cells sent from
CLICREDUNDANCY CHECK) is performed, and it is determined whether or not the result of the calculation matches that stored in the ATM cell.

The control device 18 controls each of the above-mentioned parts, and at the same time, the A of the ATM cell generated by the cell generation part 13 is controlled.
The transfer to the TM switching network 12 is controlled based on the congestion information of the ATM switching network 12. Further, the transfer of the LAN data restored by the cell disassembling unit 14 to the LAN is controlled based on the congestion information of the LAN.

Next, FIG. 4 shows the format of the ATM cell in this embodiment. In the figure, ATM
The cell has a fixed length of 53 bytes, and the first 5 bytes are A
TM header, the remaining 48 bytes are the information field (INFO
RMATION) is used.

The information field is, in this embodiment, a header 2 bytes for storing a segment type (ST), a sequence number (SN), etc., a LAN data storage area to be divided, that is, a payload 44 bytes, and effective information in the divided data. When the length is shorter than 44 bytes, it is composed of 2 bytes of a trailer in which a payload length indicating the length is stored.

FIG. 5 shows the contents of the ATM header field in the cell format shown in FIG. AT
Of the 5 bytes of the M header, the first 4 bits are a generic flow control GFC used for flow control between links.

The next 8 bits are the virtual path identifier VPI. The next 16 bits are the virtual channel identifier VCI. The next 2 bits are a payload type PT indicating the type of cell.

The next 1 bit is a cell loss priority SLP used for controlling cell discard at the time of congestion. Last 8 bits are 1 bit error correction in ATM header, 2
It is a header controller HEC for bit error detection.

FIG. 6 shows the contents in the information field in the cell format of FIG. Of the 48 bytes of the information field, the contents of each field except the divided LAN data storage area, that is, 44 bytes of the payload will be described below.

The first 2 bits of the header 2 bytes are LA
It is a segment type indicating the position of a cell, for example, when a level 3 protocol data unit (L3-PDU) as N data is divided into a plurality of cells.

For example, the head cell is an identifier BOM indicating the head, the middle cell is COM, and the last cell is EO.
The identifier M is stored in each. Next, the next 4 bits of the segment type 2 bits are a sequence number SN that is cyclically added to cells in L3-PDU units and for detecting discard in cell units.

The remaining 10 bits are reserved (not shown). The first 6 bits of the trailer 2 bytes are PLI (PAYLOAD LENG) that indicates the effective length of the divided LAN data.
TH INDICATION).

The next 10 bits are a cyclic redundancy check code CRC for error correction and detection. FIG. 7 shows the information field 48 of the SSM cell / EOM cell in this embodiment.
It is a figure which shows the content of a byte.

In this embodiment, when the level 3 protocol data unit is 48 bytes or less among the 48 bytes of the information field of the SSM cell / EOM cell, that is, 3
When there is a surplus area of more than bytes, congestion information as communication control information according to the present invention is stored in the surplus area.

In this case, the surplus area is composed of congestion information, 6 bits which is the second payload length information (second PLI), and 10 bits which is the second CRC 10, as shown in FIG.

Here, the congestion information is the congestion information of the originating ATM switch 9a of the ATM cell. The second payload length information is information indicating the effective payload length in the surplus area, that is, information indicating the length of the area in which the congestion information is stored in the surplus area.

The second CRC 10 has a calculation result for the entire surplus area, 1-bit error correction capability, and 2-bit error detection capability, and when the LAN data cell conversion device 8 on the receiving side performs the second CRC calculation, If the calculation result matches the calculation result stored in this area, it is possible to recognize that the data is stored in the surplus area.

The operation process of the ATM cell assembling system in this embodiment will be described below. When the LAN data cell conversion device 8a receives LAN data from the calling terminal 10a of the calling LAN, the control device 18 of the LAN data cell conversion device 8a causes the information detection unit 15 to detect the LAN.
While detecting congestion information of the originating LAN from the data,
This LAN data is transferred to the cell generation unit 13.

Here, the information detection unit 1 which has detected the congestion information
Reference numeral 5 designates this congestion information as the LAN data cell conversion device 8 concerned.
The cell disassembling unit 14 of a is notified. On the other hand, the cell generation unit 13
First, the LAN data is divided into 44-byte divided data, and a header consisting of a segment type, a sequence number, and a reserve, a payload length information, and a trailer consisting of CRC10 are added to each of these divided data, and level 2 is given. Create a protocol data unit for.

Further, the cell generation unit 13 adds GFC, VPI, VC to each of these level 2 protocol data.
AT composed of I, PT, RES, CLP, and HEC
An ATM cell is created by adding an M header.

At this time, the controller 18 controls the cell generator 13
The PLI (payload length information) of the ATM cell created by, particularly the ATM cell to which the identifier SSM / EOM is added as the segment type is monitored to determine whether or not the ATM cell has a surplus area of 3 bytes or more. To do.
Here, when there is a surplus area of 3 bytes or more, the congestion information of the originating ATM switch 9a is stored in the surplus area, and the second PLI and the second CRC 10 indicating the length of the congestion information are stored. To be stored.

Here, the control device 18 determines the ATM cell according to the congestion state of the destination ATM switch 9b of the ATM cell.
Control cell transfer. By the way, this congestion information is the congestion information previously stored in the ATM cell received from the destination ATM exchange 9b.

The controller 18 determines the AT by the congestion information.
When the destination ATM switch 9b, which is the destination of the M cell, is in the congestion state, the ATM cell is temporarily stored in the cell buffer 16 and transferred after a lapse of a fixed time.

On the other hand, the L on the receiving side that received the ATM cell
In the AN data cell conversion device 8b, the control device 18 is CR
The C checker 19 performs a CRC operation on the ATM cell to determine whether cell discard has occurred.

Further, the CRC checker 19 is level 3
Second CRC1 in the protocol data unit storage area of
When 0 is stored, the CRC operation of the second CRC 10 is performed, and the operation result is collated with the operation result stored in the second CRC 10.

When the two match, it is recognized that the congestion information is stored in the surplus area, and the information detector 15 detects the congestion information. The detected congestion information is notified to the cell generation unit 13. Thus, when transmitting an ATM cell to the originating side ATM switch 9a, the transfer of the ATM cell can be controlled based on the congestion information.

Further, the control device 18 transfers the ATM cell to the cell disassembling unit 14. The cell disassembling unit 14 synchronizes the ATM header of the ATM cell with
Remove TM header. Further, the header and trailer are deleted from the level 2 protocol data unit, and the divided data of the same genre are combined according to the segment type and sequence number assigned to the header to restore the LAN data.

Here, the control device 18 controls the transfer of the LAN data based on the congestion information of the LAN which is the destination of the LAN data. By the way, this congestion information is the congestion information detected from the LAN data previously received from the LAN which is the destination of the LAN data.

When the controller 18 recognizes from the congestion information that the LAN is in a congestion state, the controller 18 temporarily stores the LAN data in the LAN data storage unit 17 and transfers it after a predetermined time has elapsed.

Therefore, according to this embodiment, congestion in the ATM switching network 12 and the LAN can be suppressed to the minimum, and the multiplexing efficiency by ATM can be improved.

[0068]

According to the present invention,

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a schematic configuration block diagram of an ATM cell assembling system according to the present embodiment.

FIG. 3 is a block diagram of an internal configuration of a LAN data cell conversion device according to this embodiment.

FIG. 4 is a diagram showing a cell format in this embodiment.

5 is a specific example of the ATM header in FIG.

6 is a specific example of the information field in FIG.

FIG. 7 is a diagram showing a format of an information field in this embodiment.

[Explanation of symbols]

 1a Cell control means 1b Cell control means 2a ATM switch 2b ATM switch 3 Transfer path 4a Control section 4b Control section 5a Communication control information detection section 5b Communication control Information detecting unit 6a ... Cell generating unit 6b ... Cell generating unit 7a ... Cell disassembling unit 7b ... Cell disassembling unit 8a ... Source LAN data cell converting device 8b ... .. Calling side ATM switch 9b .. Calling side ATM switch 10a .. Calling terminal 10b .. Calling terminal 11 .. Transfer path 12 .. ATM network 13 .. Cell generating unit 14. 16: Cell buffer 17: LAN data storage 18: Control device 19: CRC checker

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location 8529-5K H04L 11/20 B (72) Inventor Hiroyuki Hatta 1015 Kamitadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Fujitsu Limited (72) Inventor Reiko Furuya 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Fujitsu Limited

Claims (5)

[Claims] 1. Asynchronous transfer communication (AT) in which data transferred between LANs and computers is divided into cell units and transferred.
M) In the network, a cell control unit (1) including a cell generation unit (6), a cell disassembly unit (7), a communication control information detection unit (5), and a control unit (4), and a transfer path (3) ), A plurality of ATM exchanges (2) for exchanging ATM cells are provided, and when the cell control means (1) receives data from a LAN or a computer, the communication control information detecting section (5) The control information of the communication to be performed with the LAN or the computer is detected from the LAN data or the computer data, and the cell generation unit (6) divides the data into fixed length data, and an ATM header is attached to each of them. The control unit (4) determines whether or not the ATM cell generated by the cell generation unit (6) has a surplus area, and generates an ATM cell. , The communication control information detection Communication control information detected by (5) is stored in the redundant areas transferred to the ATM switch (2), AT said cell control means (1) from the ATM exchange (2)
When receiving the M cell, the control unit (4) determines whether the ATM cell has a surplus area, and if it has a surplus area, whether the communication control information is stored in the surplus area. When it is determined that the communication control information is stored, the communication control information detection unit (5) detects the communication control information, and the cell disassembly unit (7) removes the ATM header from the ATM cell. At the same time, the additional information transmission system in ATM is characterized in that fixed length data from which the ATM header is removed is combined to restore the LAN data or computer data. 2. The communication control information includes a LAN, a computer,
Congestion information indicating the congestion state of each ATM network, wherein the cell control means (1), when converting LAN data or computer data into cells, according to the congestion information detected from the previously received ATM cell, 2. The additional information transmission system in ATM according to claim 1, wherein cell formation and transmission of data or computer data are controlled. 3. The cell control means (1) stores communication control information when the surplus area of an ATM cell to be transmitted is 3 bytes or more.
Additional information transmission method in TM. 4. When the LAN data or computer data is converted into cells, the cell generation unit (6), if the ATM cell has a surplus area, corresponds to the communication control information and the communication control information in the surplus area. In the cell control means (1) on the receiving side that stores the error detection code that has been stored, the control unit (4) detects the error in the surplus area based on the error detection code stored in the surplus area. The additional information transmission system in ATM according to claim 1, characterized in that if no error is detected, it is recognized that information is stored in the surplus area. 5. The additional information transmission system in ATM according to claim 4, wherein a Cyclic Redundancy Check Code (CRC) is used as the error code.