JP3439378B2 - Communication method and communication system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication method and a communication system thereof for improving the processing capability of mutual conversion between transfer data of LAN or the like and AAL type 3/4/5 ATM cells by a distributed configuration.

[0002]

2. Description of the Related Art Conventionally, when LANs such as Ethernet (registered trademark) are connected to each other via an ATM transmission system such as an ATM switching network, the LAN handles variable length packets peculiar to the LANs. , 53 in ATM transmission system
Since ATM cells with fixed byte length are handled, LAN and A
CLAD (Cell Assembly and Dis) that converts ATM cells received from the ATM transmission system into packets and conversely converts packets received from the LAN into cells at the connection portion with the TM transmission system.
assembly) processing is required. For this CLAD processing,
An address table is provided for holding the source information contained in the ATM cell received from the ATM transmission system, address information such as VPI, VCI, and the like, when a packet with a destination address specified is received from the LAN, the destination The address information that matches the address is searched from the address table, and the VP in the address information obtained by the search
The packet is made into cells using I and VCI.

Here, in such CLAD processing, since the error correction signal (CRC) is not added to the address table conversion processing of the source address and the destination address, the CRC check takes a long time and a heavy load. Therefore, AT by CLAD function and address table
Separation of the CLSF processing function for routing M cells is disclosed in Japanese Patent Laid-Open No. 8-65311 (Patent 2682).
459).

That is, a CLSF processor provided with an ATM communication line and provided with a VPI / VCI converter for converting destination information of an ATM cell received from the ATM communication line into destination information compatible with LAN, and this CLSF processor. And a CLAD processing device provided for each LAN line, and the CLAD processing device includes an A for an ATM communication line.
A generation unit for generating a TM cell, a generation unit for generating a packet adapted to a LAN for a cell received from an ATM communication line are provided, and the CLSF processing device has a transmission buffer for temporarily accumulating the ATM cell received from the CLAD processing device, ATM
BOM (beginning of message) cells or SS from cell to cell
A primary table for registering the source address (SA), VPI, and VCI information contained in the M (single segment message) cell in chronological order, an address table control unit for searching the destination address using the destination address as a key, and a destination A communication controller with a secondary table for recording addresses is described.

A conventional method will be described with reference to FIG. The ATM cell switch interface device 2 includes an agent data arbitration unit 3, a sub address SBDA allocation control unit 4, an ATM cell division / assembly CL.
It is composed of the AD unit 5, has an interface with the ATM switch device 1, and is connected to the agent data arbitration unit 3 and each of the subordinate agent devices (6 to 7) by a bus.

The agent data arbitration unit 3 arbitrates the transmission order of data (10, 11) transmitted from a plurality of agent devices 6 to 7 accommodated under the agent data, and performs CLA.
It is sent to the D section 5.

The CLAD unit 5 divides the data from each agent into ATM cells (12, 13), attaches an ATM cell header according to the VPI and VCI regulations of the ATM cell switching device 1, and sends the ATM cell switch 1 to the ATM cell switch 1.
The ATM cell (12, 13) passes through the ATM cell switching device 1 and the ATM in which the destination agent is accommodated.
It is sent to the switch interface device 14.

In the CLAD section 5 of the ATM switch interface device 14, the ATM cell is set to the sub address SBDA.
Assemble each. The SBDA distribution control unit 4 transfers the transfer data (10, 10) to each destination agent device (8, 9).
11) is sent.

[0009]

However, in general,
The ATM cell assembling time of the CLAD unit 5 is longer than the delay time transmitted through the ATM cell switching device 1.
As shown in FIG. 5, the CLAD unit 5 also exists in the ATM cell switch interface device 14 of the ATM cell switching device 1, and the delays are concentrated by the upstream and downstream CLAD units 5 of the ATM cell switching device 1. As a result, the processing capacity of the entire system does not increase.

The present invention reduces the processing time of transmission data by the ATM cell switch interface device of the ATM cell switching device, transfers the ATM cell assembling time to the agent device, and distributes the ATM cell assembling / disassembling process. Is an issue.

[0011]

SUMMARY OF THE INVENTION The present invention provides a communication system comprising an agent device for inputting / outputting transfer data, an ATM switch interface device having a buffer function, and an ATM switch device for exchanging ATM cells. The agent device receives the transfer data and A
TM cell AAL type 3/4 (hereinafter referred to as ATM cell) format is mutually converted, and the sub-destination address (which is assigned to the payload of the message start (BOM) cell in the ATM cell by the ATM switch interface device ( SBDA) is retrieved and transmitted, and the AT
The agent device of the destination of the ATM cell header from the M switch device is searched and sent.

The present invention also provides an agent device for inputting / outputting transfer data, and an ATM having a buffer-like function.
In a communication method of a communication system comprising a switch interface device and an ATM switch device for exchanging ATM cells, in the agent device, a cell assembling / disassembling (CLAD) unit is used to assemble and / or assemble data between the transfer data and an ATM cell format. Alternatively, the AT is decomposed.
The M switch interface device holds the last ATM cell from the start ATM cell from the agent device and sends it to the ATM switch device, searches the destination address from the ATM cell from the ATM switch device with a search table, and It is characterized in that it is sent to the agent device.

In the system according to the invention, ATM cell A
Be of AL type 3/4 (hereinafter ATM cell) format
ginning Of Message (hereinafter, BOM) Sub-destination address (hereinafter, SBD) assigned to the payload of the cell
By converting the A: SuB Destination ADdress) together with the ATM cell header into a header by the ATM switch interface device, an ATM cell dividing / assembling unit (hereinafter, CLAD: Cell Assembly an) having a large processing delay is generated.
d Disassembly) is not placed on the ATM switch interface device, but on each subordinate agent device.

The present invention eliminates the CLAD function having a large processing delay from the ATM switch interface device in which the load is concentrated at the time of overload by the above-mentioned device configuration,
By arranging the D function in each agent device, it is possible to distribute the load in the system and improve the processing capacity of the entire system.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to the drawings.

(1) Description of Configuration FIG. 1 is a configuration diagram of a LAN / ATM conversion system according to this embodiment. In FIG. 1, reference numeral 1 is an ATM switch device. Further, reference numerals 2 and 13 denote ATM switch interface devices which have an interface with the ATM switch device 1 and accommodate the agent devices 6 to 9 under their control. Reference numeral 3 denotes each agent data arbitration unit, which arbitrates the transmission order of cells transmitted from the plurality of agent devices 6 to 9 accommodated under the agent data and transmits the arbitrated data to the ATM switch device. Reference numeral 4 denotes a header search unit, which is an ATM switch device 1
From the ATM cell header from the message start BOM,
Using the sub-destination address SBDA in the payload inside the single segment message SSM, the lookup table of 5 is referenced, the ATM header is converted, and the ATM cell is sent to each of the agent devices 6-9.

Here, the ATM switch device 1 delivers the data to the destination according to the destination information in the header portion of the ATM cell. Also, ATM switch interface devices 2, 1
3 updates the header part according to the information of the header part of each ATM cell and sends it to the ATM switch device 1, and the ATM switch device 1 selects and sends the agent device to the destination according to the ATM cell. The agent devices 6 to 9 are devices that understand the user's intention and execute processing based on autonomous judgment. In the ATM system, nodes and routers that execute network routing processing and the like from the header of an ATM cell. , It may have a function as a bridge.

Further, 10 is an ATM cell communicated between the agent devices 6 and 9, and 11 is an agent device 7 or 8.
It is an ATM cell communicated between them. Reference numeral 12 is a cell division / assembly unit CLAD of each agent device 6-9.
In addition, after each agent device 6 to 9 has transmitted one piece of data from the CLAD 12 unit, if there is no reply data from the agent device 6 to 9 of the transmission partner,
Do not transfer the next data. That is, the data communication in the present invention is outstanding.

The AAL (AT
M Adaptation Layer: Has the role of decomposing user information into ATM cells and restoring the original user information from the cells) 3 /
4 is used in connectionless service (SMDS) of the public network, and is particularly used in ATM-LAN. As an AAL layer, SAR (Segmenta) is provided on the ATM layer of the physical layer.
tion And Reassembly) layer, CPCS (Common Part)
Convergence Sublayer) layer, SSCS (Service S)
pecific Convergence Sublayer) and the upper layer above it, and the SAR layer is the CPCS-
A PDU is divided into ATM cells, and a sequence number and CRC are added as necessary.

In this AAL3 / 4, CPCS-PDU
For SAR-PDU and SAR-PDU, a 4-byte header and trailer are added to the user data, and the main functions are frame length display / buffer size reservation / error check function by frame number and 4-byte integer. It is a function to double. 2 bytes each for the head / trailer is attached to the SAR, and the first cell BOM of the SAR type,
The middle cell COM, the final cell EOM, and the single cell message SOM are identified. Also, it has a function to detect cell loss by cell sequence number and error detection for each cell by CRC, and can simultaneously multiplex multiple packets on one VC with 10 bits of MID (ID message) in the SAR type. Also has a function that can be identified on the receiving side.

Regarding this AAL3 / 4, in the present embodiment, the CLAD 12 of the agent devices 6 to 9 decomposes the transfer data of the packet cells of fixed length or variable length into ATM cells, and assembles the ATM cells into the original transfer data. Therefore, the agent data arbitration unit 3 of the ATM cell switch interface device 2 determines which of the BOM, SSM, COM, and EOM is in the ATM cell, and when the BOM or SSM pattern is detected, the BOM is detected. ,
The ATM switch device 1 judges the destination address from the SBDA in the payload of the SSM and performs buffering.
In the ATM cell switch interface device 2 in the destination direction from the ATM switch device, the header search unit 4 first monitors the SAR-PDU header, and the BOM or S
The SM pattern is detected and the VPI of the ATM cell header is detected.
Based on the VCI and the SBDA contained in the payload, the BOM or SSM is sent from the lookup table 5 to each agent device, including the ATM cell header.

(2) Description of Operation The operation of this embodiment will be described with reference to FIGS. In the ATM cell used in this embodiment, when the data transmitted from each agent device 6 to 9 is converted into an ATM cell and transmitted, the ATM switch interface devices 2 and 13 have a long data length and a single ATM. If the cell cannot communicate, it is divided into multiple cells for transmission. At this time, as shown in FIG. 2, the first cell is the message start BOM (Beginning Of Message), the last cell is the message end EOM (End Of Message), and the middle cell is the message continuation COM (Continuation Of Message).
If the data length is short and a single ATM cell can be used for communication, the ATM cell is called a single segment message SSM.
(Single Segment Message). Each Messag mentioned above
The identifier of e is the segment reassembly protocol data unit SA
R-PDU (Segmentation and Reassembly-Protocol)
Data Unit) present in the header. The SAR-PDU footer has an ATM cell effective length and a cyclic redundancy check CRC.

ATM cells (10 and 11 in FIG. 1) are AT
It is sent to the ATM switch interface device (13 in FIG. 1) in which the destination agent device is accommodated via the M switch device (1 in FIG. 1). VPI (Virtual Path Identifie) of ATM cell header in ATM switch device
In r) and VCI (Virtual Channel Identifier), VPI is a destination address and VCI is a source address. When communicating with the system shown in FIG.
ATM of TM switch interface device (2 in FIG. 1)
The connection port number of the switch is the source address (VCI)
The ATM switch interface device (1 in FIG. 1)
The connection port number of the ATM switch of 3) becomes the destination address (VPI).

The ATM cell switch interface device (2, 13 in FIG. 1) is directed from each agent device (6, 7 in FIG. 1) to the ATM switch device (1 in FIG. 1), A
It has a bidirectional function from the TM switch device (1 in FIG. 1) to each agent device (8, 9 in FIG. 1), but as an explanation, an ATM cell switch interface device is provided for each direction. It will be described in the state of being provided separately.

(1) Each agent device (6 in FIG. 1)
7) from the ATM switch device (1 in FIG. 1) to the ATM cells (10 and 11 in FIG. 1) sent from the agent devices 6 and 7 to the ATM switch interface device (2 in FIG. 1), In the agent data arbitration unit 3, the ATM cell is BOM, SSM, CO
If the BOM or SSM pattern is detected by determining which of M and EOM, S in the payload of BOM and SSM is detected.
Buffering is performed by judging from BDA (21 in FIG. 2). After that, as soon as the EOM from each agent is detected, each agent data arbitration unit (3 in FIG. 1) sends A
Send TM cells. In each agent data arbitration unit 3, there is a buffer for each SBDA, and when ATM cells are sent from one buffer, ATM cells are not sent from other buffers (see FIG. 3).

(2) From the ATM switch device (1 in FIG. 1) to the agent device (8, 9 in FIG. 1) direction ATM switch interface device (13 in FIG. 1), in the header search unit (4 in FIG. 1), SA in the ATM cell (10.11 in FIG. 1) input from the ATM switch device 1
Monitor the R-PDU header (23 in FIG. 2) and check BOM or S
When the SM pattern is detected, the VP of the ATM cell header is detected.
Based on I, VCI (32 in FIG. 4) and SBDA (34 in FIG. 4) included in the payload 25, the ATM cell header output from the lookup table (36 in FIG. 4) is derived.

After that, BOM or SSM is sent to each agent 8, 9. Functions of each agent data arbitration unit (3 in FIG. 1), ATM switch device VPI, V
According to the CI regulation and the communication protocol of the present invention, the number of data transmitted from each of a plurality of agent devices to one agent device is one.
For the header conversion of, it is only necessary to search the outgoing ATM cell header from the incoming ATM cell header. COM,
It is not necessary to put SBDA in EOM.

In the above-described embodiment, the variable-length packet is decomposed into ATM cells, and the ATM cells are assembled into variable-length packets by the CLAD 12 in each agent. The amount of data can be drastically reduced, data transmission can be prevented from being delayed due to the conventional cell assembly / disassembly, and the data disposal can be greatly reduced. From the above, the present invention is used for connection-oriented data packets of AAL type 3 used for burst transfer, and connectionless data such as SMDS (high-speed data exchange service on the order of mega bits / second) of AAL type 4. By using it for a packet, it can be adaptively applied due to the difference in load between the interface device and the agent device for ATM cells / variable length packets.

In the above embodiment, the AAL type 3 is used.
/ 4 was mainly explained, but AAL type 3 /
In addition to basic functions such as cell division and assembling, AAL type 5 connection-type data communication and signaling services that have advanced 4 are equipped with error detection and retransmission control functions in the cell information section. Therefore, the present invention can be applied to cell disassembly and assembly.

[0030]

As described above, according to the present invention, the following effects can be obtained.

By allocating the sub-destination address SBDA to the message start BOM and the single section message SSM, each agent can be provided with the function of the cell assembling / disassembling unit CLAD. By providing the search function without the function of the disassembling unit CLAD, it is possible to reduce the influence of processing delay in the ATM switch interface device, distribute the load in the system, and improve the processing capacity of the entire system. .

Also, an AT that can use only a limited path
Even in the M cell switch device, a large number of agent devices can be connected, and the agent devices can be configured to communicate by ATM cells.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of each unit of a communication system of the present invention.

FIG. 2 is an explanatory diagram of assembly / disassembly of a CLAD unit in the agent device of the present invention.

FIG. 3 is an explanatory diagram of an agent data arbitration unit of the ATM cell switch interface device of the present invention.

FIG. 4 is an explanatory diagram of a header search unit of the ATM cell switch interface device of the present invention.

FIG. 5 is a diagram showing a device configuration example of a conventional communication system.

[Explanation of symbols]

1 ATM cell switch device 2, 13 ATM cell switch interface device 3 Agent data arbitration unit 4 Header search unit 5 Search table 6, 7, 8, 9 Agent device 10, 11 ATM cell 12 CLAD (cell assembly / disassembly unit) 21 Sub Destination address (SBDA) 22 ATM cell header (VPI, VCI) 23 Header of segment reassembly protocol data unit (SAR-PDU header) 24 Footer of segment reassembly protocol data unit (SAR-PDU footer) 25 Payload (data) 26 Padding (Fit) 31 Outgoing ATM cell header 32 Incoming ATM cell header 33 Sub-destination address (SBDA) 34 SAR-PDU header 35 SAR-PDU footer 36 Search table

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Sakiyama No. 1 Kaigai, Ichinoseki, Iwate Prefecture, Tohoku Nippon Electric Co., Ltd. (72) Yoichi Yaegashi No. 1 Kagokai, Ichinoseki, Iwate Prefecture, Tohoku NEC Corporation (56) References JP-A 5-260077 (JP, A) JP-A 7-143180 (JP, A) JP-A 7-321794 (JP, A) JP-A 8-65311 (JP, A) Kaihei 8-102743 (JP, A) JP 8-102745 (JP, A) JP 10-215254 (JP, A) JP 10-224371 (JP, A) JP 10-336184 ( JP, A) JP 11-4224 (JP, A) JP 11-32058 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/28

Claims (2)

(57) [Claims] 1. A sub-destination even if the sub-destination address changes.
Make sure the VPI / VCI corresponding to the address does not change
The rolling sub destination address having a relationship that always a plurality of sub-destination address exists for the same VPI / VCI
In addition to transmission data, a plurality of transmitting-side agent device said the transfer data sub destination address is added to accommodate the payload of one or more ATM cells and outputs the ATM cell, transmitting the plurality A transmission side AT that inputs an ATM cell from the agent on the side, buffers the input ATM cell in a unit of transfer data, and outputs the buffered ATM cell to the ATM cell switching device
The M cell switch interface device and the ATM cell switch device input the ATM cell, and the sub-destination address is added to the receiving-side agent device corresponding to the sub-destination address of the ATM cell having the sub-destination address in the payload. An ATM cell switch interface device on the receiving side for outputting one or more ATM cells having the transferred data transferred in the payload; and an ATM cell input from the ATM cell switch interface device on the receiving side, which is in the payload of the input ATM cell. A communication system comprising: a plurality of receiving-side agent devices that combine transfer data and restore original transfer data. 2. A sub-address to each sending agent
V corresponding to the sub-destination address even if the destination address changes
The same VPI / VC so that the PI / VCI does not change
A sub-destination address having a relationship in which a plurality of sub-destination addresses always exist for I is added to the transfer data, and the transfer data to which the sub-destination address is added is accommodated in the payload of one or more ATM cells. Let the AT
Outputting M cells, and transmitting ATM cell switch interface device, receiving ATM cells from a plurality of transmitting agents, buffering the input ATM cells in transfer data units, and outputting to the ATM cell switching device In the ATM cell switch interface device on the receiving side, the ATM cell is input from the ATM cell switch device, and the AT having the sub-destination address in the payload
Outputting to the receiving agent device corresponding to the sub-destination address of the M cell one or more ATM cells having transfer data to which the sub-destination address is added in the payload; and in each receiving agent device, ATM on the receiving side
A method of inputting an ATM cell from a cell switch interface device, combining transfer data in a payload of the input ATM cell to restore original transfer data, and a communication method.