JPH09252311A - Atm communication equipment and method for controlling congestion of communication network by using the equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly execute congestion control by generating promptly an RM cell added with congestion information in a communication equipment in which congestion occurs, and transmitting it to a communication terminal or the communication equipment transmitting a cell to be the factor of cell buffer congestion. SOLUTION: When the quantity of inter-device cells accumulated in cell buffers 2a, 2b exceeds a threshold, the congestion is judged to have occurred, and a cell buffer detecting part 3 detects the identifier of the cell buffer in which the congestion occurred, and reports it to line dealing with parts 100a, 100b. Cell buffer identifier-to- received cell header information retrieving parts 5a, 5b generate newly a congestion reporting RM cell having the same VPI and VCI as the VPI snf VCI of the detected identifier in the header. Selector parts 7a, 7b receive the control of the information retrieving parts 5a, 5b, and insert the congestion reporting RM cell into the transmission cell, and output it to interfaces 300a, 300b, and transmit it directly to a cell transmitting origin making the congestion. Thus, response time till the communication terminal or the communication equipment transmitting the congestion factor cell slows down transmission cell speed is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM communication device in an ATM communication network, and more particularly to an ATM communication device suitable for congestion control of the communication network and a communication network control method using the same.

[0002]

2. Description of the Related Art As a conventional congestion control processing method in an ATM communication network, a document number issued by the ATM Forum (ATM Forum / 94-0438R2) is used.
"Closed-Loop Rate-Based T
EP described in "raffic Management"
RCA (Enhanced Proportional)
The Rate Control Algorithm is known.

This method uses an RM cell (Resource).
The communication is notified of the congestion detected in the network by using the management cell (Management Cell), and the traffic control (for example, lowering the cell transmission rate) is performed so that the communication device avoids the congestion. Specifically, if the source communication device of the cell sends the RM cell at appropriate intervals in addition to the sending of the user cell for transmitting / receiving information between normal users, a device in the network through which the user cell passes. If congestion occurs in the RM cell, the user cell and the RM cell also pass through this device and are once transmitted to the termination point (the reception side device of the user cell), and then the congestion information is added to the RM cell at the termination point and the transmission source By sending back to the device, it performs traffic control such as lowering the cell transmission rate to avoid congestion in the communication network by notifying the communication terminal or communication device that is transmitting the user cell that is the cause of congestion and avoiding congestion in the communication network. By controlling the cell transmission rate of the user cell transmission source, it is possible to effectively use the transmission band while avoiding deterioration of communication quality due to network congestion.

Another congestion control method is disclosed in Japanese Patent Laid-Open No. Hei 7
When a communication device monitors a buffer provided on the input line side and detects congestion as shown in Japanese Patent Laid-Open No. 183886, the generation of congestion is directly notified to the communication device that has transmitted the cell in the previous stage, and the cell transmission rate is lowered. There are ways to start and stop. According to this method, the congestion notification is speeded up and the amount of cells input to the device is immediately controlled, so that congestion can be avoided even if the amount of the input buffer in the device is small.

[0005]

Among the above ATM congestion control methods, in the former, the cell transmission rate at the user cell source is reduced in order to avoid congestion after a device in the network falls into the congestion state. During this period, the RM cells inserted in the user cell stream are transmitted once to the receiving terminal or the communication device that is the RM cell termination point, and congestion information is added to this RM cell to add the congestion information to the RM cell originating terminal. Alternatively, since the operation of returning to the communication device and detecting the congestion information of the RM cell is performed, the congestion state continues during that time. That is, during the period until the transmission source communication device starts the traffic control, there is a risk that the cell will overflow and be lost (occurrence of cell discard) in a cell buffer or the like for exchanging cells. In order to avoid such a phenomenon, even if the response time until the user cell transmission speed in the RM cell originating terminal or the communication device is lowered is long, the cell buffer is discarded in the cell buffer in the communication device in the network. It was necessary to prepare a large amount of cell buffer so that it would not exist. The need for this buffer increase means that the network becomes large in scale, the communication devices are connected in multiple stages, the propagation delay increases (the response time increases), the number of lines to process increases and the number of cells input to the communication device increases. As the amount increases, it becomes more and more remarkable.

On the other hand, the latter method of speeding up the congestion control solves the former problem of reducing the amount of buffer, but when congestion occurs as a result of cells being input from a large number of sources, Since it is not configured to check the transmission source and notify the transmission source of congestion, similar to the case where communication devices are connected in multiple stages in a communication network, when congestion occurs in the output buffer of the exchange, depending on the occurrence state of congestion. In some cases, the essential congestion avoidance of controlling the sender when congestion occurs cannot occur.

An object of the present invention is to provide a congestion control method which is an improvement of the above-described congestion control method for a communication network, and an ATM communication device having a configuration suitable for congestion control. Specifically, it is possible to quickly notify the communication device of the congestion that has occurred in the communication network. Moreover, this notification can be surely notified to the cell source communication device that is the cause of congestion, congestion control method of the communication network capable of performing high-speed traffic control of the source when congestion occurs, it It is to provide an ATM communication device for realizing the above.

Another object of the present invention is to, in an ATM communication network, when congestion occurs in any communication device in the network, when this communication device detects the congestion, the cell causing the congestion is identified. Providing a congestion control method and an ATM communication device capable of notifying the sending communication terminal or communication device of this and shortening the response time until the transmission cell speed is lowered, and further effectively using the transmission band To do.
That is, a communication terminal or a communication device that is transmitting a user cell that is the cause of congestion is notified of congestion at high speed and reliably, and traffic control such as lowering the cell transmission speed to avoid congestion in the communication network is performed. It is therefore an object of the present invention to provide a congestion control method and an ATM communication device for effectively utilizing a transmission band while avoiding deterioration of communication quality due to network congestion by controlling a cell transmission rate of a user cell transmission source.

Another object of the present invention is a structure suitable for a communication network for controlling congestion, in which a cell loss or the like due to congestion can be avoided even if the amount of cell buffer prepared in each communication device is small. To provide an ATM communication device.

Further, another object of the present invention is to provide an A configuration in which when congestion is detected, the origin of the congestion is detected and notified at high speed.
It is to provide a TM communication device.

[0011]

In order to solve the above-mentioned problems, according to the present invention, a detection unit for detecting a congestion of a buffer in a communication device, and a transmission for analyzing a transmission source which inputs a cell into a buffer in which the congestion occurs An original analysis unit, a notification cell generation unit that notifies congestion, and a transmission unit that transmits the notification cell to the cell transmission source according to the analysis result. Then, when it is detected that the congestion state in any communication device of the communication network,
This communication device identifies the communication device of the transmission source that inputs the cell causing the congestion and directly notifies the cell transmission source device of the occurrence of the congestion. In the cell source device that received this notification, by performing traffic control such as immediately reducing the cell transmission speed to perform congestion control of the communication network, buffer overflow and cell loss in the communication device that detected congestion The congestion control method is used to prevent this.

More specifically, an ATM communication device used in a communication network, an interface for inputting / outputting ATM cells, a cell buffer for accumulating cells for exchange, etc.,
In an ATM communication device consisting of a control unit for controlling the setting of an interface and a cell buffer, a congestion cell buffer detection unit for detecting a congestion state for each cell buffer, and the congestion cell buffer detection unit for detecting the congestion state based on the identifier of the cell buffer A source search unit that searches for a cell source that has input a cell in a cell buffer, and an RM cell generation unit that creates an RM cell that notifies congestion occurrence and sends an RM cell to the searched cell source .

The cell source search unit is a path identifier (VPI) or a connection identifier (VCI) in the header of the received cell, which is a path identifier added at the time of receiving the cell input to the cell buffer in the congested state. ) From the cell buffer identifier, the cell buffer identifier-to-received cell header information searching unit. Then, the RM cell generation unit adds the retrieved VPI or VCI to the header of the RM cell, and transmits this RM cell to the transmission source that has transmitted the cell causing the congestion to the device, An RM cell is provided to a congestion notification RM cell generation unit that generates an RM cell to which congestion information is added based on the retrieved reception cell header information, and a communication terminal or communication device that is transmitting the cell causing the congestion. It is composed of an output unit for sending. In addition, the output of the congestion cell buffer detection unit is used in a device such as a maintenance cell so that a cell source can be searched and an RM cell can be transmitted even in a communication device having a structure in which a cell buffer, an interface, and a control unit are separated. A congestion cell buffer identifier notifying unit for notifying the search unit or the RM cell generating unit using a signal of a predetermined format may be provided inside the device.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An ATM communication apparatus according to the present invention and a congestion control method for a communication network using this apparatus will be described below in detail with reference to the drawings. FIG.
FIG. 2 is a network configuration diagram showing a schematic configuration and a congestion control operation of an ATM communication network, and FIG. 2 is a cell configuration diagram showing a configuration of ATM cells (user cells, RM cells, etc.) transmitted and received in the ATM communication network. First, the congestion control operation using the RM cell in the ATM communication network will be described.

As shown in FIG. 1, the ATM communication network includes six communication terminals 501 to 506 and three ATM communication devices 60.
1 to 603, these devices are connected by a cell connection (hereinafter referred to as a connection) such as C1 to C4 to perform cell transmission / reception and exchange between communication terminals, and communication terminals 501 and 504. Communicate via connections C1 and C4 via communication devices 601 and 602, communication terminals 502 and 505 communicate via connections C2 and C5 via communication devices 601 and 602, and communication terminal 503
And 506 communicate with the connections C3 and C6 via the communication devices 601 and 603.

In a communication network that performs congestion control using RM cells, each communication terminal has a communication terminal (eg, communication terminal 5
From 01 to 504 (route R1), the RM cell 15 for adjusting the transmission rate of the user cell 14 of its own is generated, periodically inserted between the user cells 14 and transmitted. Communication terminals 501 to 503 to communication terminals 504 to 50
If there is no congestion in the buffer such as the cell buffer 700 during the process of transferring the user cell 14 to the opposite communication terminal 6 to 6, the RM cell 15 sent by each of the transmission side communication terminals 501 to 503 remains as it is. It is returned and returned by each of the receiving side communication terminals 504 to 506 which are communication terminals. Then, the transmitting side communication terminals 501 to 503 again receive the RM cells 15 returned and returned, and when it is confirmed that the congestion information is not included, increase the transmission rate of their own user cells.

Here, the communication device 602 of the communication device 601
When congestion occurs in the cell buffer 700 at the transmission end to the communication terminal 601, when the communication device 601 passes the user cell 14 through the congestion cell buffer 700 in the process of transferring the user cell 14 to the opposite communication terminal. While the congestion state continues, a mark indicating that the congestion cell buffer 700 has been passed is added to the headers of all the user cells 14 transferred according to the connections C1 and C2 that pass through the congestion cell buffer 700. It should be noted that this mark is added to the PT field 100-4 in the cell header 100) described later. In the communication terminals 504 and 505, the received R
When it is confirmed that the mark is added in the header of the user cell 14 received immediately before the M cell 15, the reception RM
The congestion information is added to the header of the cell, and the information is returned to the communication terminals 501 and 502 which are the return sources. The communication terminals 501 and 502 receive the RM cell 15 with congestion information and reduce the transmission rate of their own user cells. By controlling the cell transmission rate of the transmission source communication terminal of the user cell 14 by the above procedure, the transmission band is effectively used while avoiding network congestion.

According to the congestion control method of the present invention, in addition to the RM cell generated by the cell source communication device for controlling the cell transmission rate and returned and returned by the receiving communication device, the nuclear communication device in the network is used as the communication device. If congestion occurs in the device, a new RM cell is generated in this device, and the RM cell is transmitted to the communication terminal or communication device that is transmitting the user cell causing the congestion. Faster than the processing of
The configuration is configured to reliably notify the communication terminal or the communication device of the congestion, and the congestion control of the communication network is executed.

FIG. 3 is a network configuration diagram showing a schematic configuration and a congestion control operation of the ATM communication network of the present invention. Hereinafter, the ATM congestion control method of the present invention will be described with reference to FIG. A
The TM communication network is composed of six communication terminals 501 to 506 and three ATM communication devices 1001 to 1003 according to the present invention (detailed configuration and operation will be described later), and these devices are connected as C1 to C4. Cell connection (hereinafter referred to as a connection) to perform cell transmission / reception and exchange between communication terminals.
The communication terminals 502 and 505 communicate with each other via the communication devices 100 and 01 via the connections C1 and C4.
1 and 1002 to communicate with each other through the connections C2 and C5, and the communication terminals 503 and 506 communicate with each other by the communication device 1001.
This is an example in which the communication is performed by the connections C3 and C6 via the and 1003, and the communication network has a configuration similar to that of FIG. Further, each of the communication terminals 501 to 503 on the transmitting side generates an RM cell 15 for adjusting the transmission rate of the user cell 14, periodically inserts it between the user cells, and sends it out. ˜506, operation of returning the RM cell 15 back, RM cell 1 when congestion is detected
The processing procedure of 5 is the same as the congestion control operation of the communication network shown in FIG.

In the ATM communication apparatus of the present invention and the communication network using the ATM communication apparatus, for example, when congestion occurs in the cell buffer 700 at the transmission end from the communication apparatus 1001 to the communication apparatus 1002, the communication apparatus 1001 detects this congestion. All the cells 14 transferred according to the connections C1 and C2 passing through the cell buffer 700 in which the congestion is generated as in the conventional process while the congestion state continues as in the communication device shown in FIG. Of the VPI 100-2 and VCI 100- at the time of cell reception, which is added to the header 100 of the user cell 14 input to the cell buffer 700, while adding a mark indicating that congestion has occurred to the header of
3 is searched to identify the communication terminals 501 and 502 of the transmission source. Then, the RM cell 16 for notifying the congestion is newly added to the communication device 1001 separately from the RM cell 15 described above.
VPI100-2 and VCI100- that are created by the above and correspond to the respective transmission source communication terminals 501 and 502.
3 is added to the header 100 and each communication terminal 501 and 502
(Route R1). Incidentally, when the congestion cell buffer 700 does not exist in the cell transfer process as in the communication from the communication terminals 503 to 506, 506 to 503, 504 to 501, and 505 to 502, it is the same as the conventional processing described above. is there.

By the above processing, congestion control is surely notified to the communication device of the transmission source, and moreover, congestion control with a quicker response than the conventional control method is realized. Therefore, it is possible to implement and apply a communication device in which cell discard does not occur even when the amount of buffer provided in each communication device is reduced, and an economical, high-speed and high-performance congestion control communication network is provided.

A configuration example of the ATM communication device having the congestion control function according to the present invention will be described below in detail.
FIG. 4 is a block diagram of an ATM communication device having a congestion control function according to the present invention. FIG. 5 is a cell configuration diagram showing the configuration of the internal cell 17 used inside the ATM communication device.

The ATM communication device 1000 includes a plurality of line corresponding units 100 (100a to 100b in this embodiment) for inputting and outputting ATM cells on the line 300, a switch unit 200 for exchanging ATM cells, and the line corresponding unit. 100 and a connection setting unit 8 which is a control unit for controlling the switch unit 200. The line conversion unit 100 includes a header conversion unit 1 (1a and 1b) and a congestion state detected in the device to cause the congestion. A cell buffer identifier pair reception cell header information retrieval unit 5 (5a and 5b), which is a cell transmission source retrieval unit that retrieves and searches a transmission source communication device of a cell that becomes a cell, and a congestion notification RM cell 16 that is sent to the cell transmission source. Congestion notification RM cell generation unit 6 (6a, 6b), and selector unit 7 (7 that inserts the congestion notification RM cell 16 into the line 300 and transmits to the cell source. And 7b) and with a. Further, the switch unit 200 includes a cell buffer unit 2 (2a and 2b) corresponding to a cell destination line that stores and exchanges the input user cell 14, a cell buffer detection unit 3 that detects a congested cell buffer, and a detection result. The call path 400 to the line interface
(400a and 400b), and the congestion cell buffer identifier notification unit 4 is provided.

The operation of the ATM communication device 1000 will be described below. The header conversion units 1a and 1b are connected to the line 300a1.
, And VPI 100-2 and VCI 100-2 added to the header 100 of the received cell input from the switch unit 200 after the cells are exchanged by the switch unit 200.
100-2 and VCI 100-3, as well as routing information (cell buffer identifier) 17-which cell buffer 2 (2a or 2b) is to be input with the input concealable for cell exchange in the switch unit. 1 is added to the header 100 of the in-apparatus cell 17. Since the ATM communication device 1000 shown in the present embodiment does not use the congestion information display area 17-2 added to the in-device cell of FIG. 5, the in-device cell 17 not added is used here (this congestion An example using the information display area 17-2 is
It will be separately described later. ).

The cell buffer unit 2 transfers the in-device cell 17 to the cell buffers 2a, 2 according to the routing information 17-1.
By allocating and accumulating in b, each line corresponding unit 100
Replace with a and 100b.

The congestion cell buffer detection unit 3 determines that congestion has occurred in the cell buffers 2a and 2b when the amount of the in-device cells 17 accumulated in each cell buffer exceeds a preset threshold value. The identifier of a cell buffer in which congestion has occurred (congestion cell buffer identifier) is detected. In this embodiment, the routing information 17-1 added to the accumulated cell is used as it is as the congestion cell buffer identifier.

The congestion cell buffer identifier notifying unit 4 sends the cell buffer identifier (routing information 17-1) of the congestion cell buffer detected by the congestion cell buffer detecting unit 3 via the communication paths 400a and 400b to the line corresponding unit 100a,
Tell 100b.

A cell buffer identifier-received cell header information retrieval unit 5 for retrieving a cell source from the detected congestion state
a and 5b are for receiving the user cell 14 input to the congestion cell buffer using the congestion cell buffer identifier (17-1) received from the congestion cell buffer identifier notifying unit 4 via the communication paths 400a and 400b. The reception VPI and VCI (header conversion unit 1a) added to the header 100
And VPI and VCI before header conversion in 1b). The configuration and operation of the present cell buffer identifier pair received cell header information retrieval unit 5 will be described later in detail with reference to the drawings.

The congestion notification RM cell generators 6a and 6b are
A congestion notification RM cell 16 having a VPI and VCI similar to the received VPI and VCI corresponding to the cell source searched by the cell buffer identifier / received cell header information searching units 5a and 5b is generated. In addition, congestion notification RM
The cell 16 is an RM cell that is newly created by this device in order to notify the source of the cell input to the congestion cell buffer of the congestion.

The selector units 7a and 7b are controlled by the cell buffer identifier / received cell header information retrieval units 5a and 5b, and the in-device cells output from the cell buffer unit 2 when the congestion notification RM cell 16 does not occur. The header (routing information 17-1) of 17 is deleted and is output to the interfaces 300a2 and 300b2 as a transmission cell (the user cell 14 and the RM cell 15 returned from the receiving side device), and the congestion notification RM cell is output. 16 occurs, the congestion notification RM cell 16 is inserted into the transmission cell and the interfaces 300a2 and 300b are inserted.
Output to 2.

The connection setting unit 8 stores a table for storing header conversion information in the header conversion units 1a and 1b via the communication paths 800a and 800b in accordance with an instruction from a user or a maintenance person (see FIG. (Not shown) and stores the information for searching the reception VPI and VCI from the cell buffer identifier 17-1 provided in the cell buffer identifier / reception cell header information searching units 5a and 5b described below. Set the bull.

FIG. 6 shows a cell buffer identifier / received cell header information retrieval unit 5 which serves as a cell transmission source retrieval unit according to the present invention.
It is a block block diagram which showed the structure of (5a and 5b). Cell buffer identifier vs. received cell header information retrieval unit 5
Is a CAM (Contented Addressab)
le Memory 2001 and RAM (Random)
It is composed of two tables using Access Memory 3001. With these tables, the congestion cell buffer identifier (17-1) was used as a key to hold the cells to be input to the cell buffer in which congestion occurred before header conversion by the header conversion units 1a and 1b. The cell source can be searched by searching the VPI and VCI of the reception header. That is, in the table, the cell buffer identifier (routing information 17-1 in this embodiment) and the VPI and VCI of the received cell are stored and set, and the retrieval is performed. In order for the setting unit 8 to establish a connection and convert a header according to an instruction from a user or a maintenance person, the VPI and VCI of the reception cell and the header are stored in another table (not shown) provided in the header conversion units 1a and 1b. The communication path 800 includes routing information 17-1 that specifies the correspondence between the converted transmission cell and the VPI and VCI, and which cell buffer to input the reception cell for cell exchange.
The same configuration is adopted when setting via a and 800b.

As shown in FIG. 6, the table is CAM20.
01 and the RAM 3001 are combined, and the VPI 100-2 and the VCI 100-3, which are assigned when the cell buffer identifier (routing information 17-1) and the cell input to the cell buffer from the connection setting unit 8 are received.
Is provided as data for the table. CAM200
A cell buffer identifier is stored as the data for comparison and collation in the data storage area for comparison and collation 1, and a pointer number assigned to each cell buffer identifier is stored in the data storage area for output. Also, R with the pointer number as the address
The storage area of the AM 3001 stores the VPI and VCI assigned when the cell input to the cell buffer indicated by the cell buffer identifier is received.

When the cell buffer identifier / received cell header information retrieval units 5a and 5b for which the table is set as described above receive the congestion cell buffer identifier from the congestion cell buffer identifier notifying unit 4, the comparison and collation data of the CAM 2001 is received.
Data for comparison and collation equal to the congestion cell buffer identifier is retrieved from the data storage area, the pointer value of the output data where the collation is obtained is read, and stored in the storage area of the RAM 3001 which uses this pointer value as an address. Value, that is, the VPI and VCI assigned at the time of reception of the cell input to the cell buffer in which the congestion indicated by the congestion cell buffer identifier is received, as a result of identifying the communication device of the cell source, for congestion notification The RM cell generation unit 6 is notified.

As shown in the specific example of FIG. 6, the connection is such that the user or maintenance person converts the header of the received cell whose VPI is A and whose VCI is a, distributes it to the cell buffer whose cell buffer identifier is n, and outputs it. , When the connection setting unit 8 is instructed to establish the cell buffer identifier-reception cell header information retrieval unit 5a,
Information of reception VPI = A, VCI = a, and cell buffer identifier = n is given to 5b via the communication paths 800a and 800b, and n is received as the comparison and collation data of the CAM 2001 in the storage area of the RAM 3001. A,
VCI = a is R as output data of CAM2001
The address P of the storage area of the AM 3001 is stored. Here, when congestion occurs in the cell buffer whose cell buffer identifier is n, the congestion cell buffer identifier notifying unit 4 notifies the congestion cell buffer identifier = n, and the cell buffer identifier-received cell header information searching unit 5a, 5b. Then, the value of n is found in the comparison and collation data storage area, the output data P is read, and the data A and a stored in the storage area of the RAM 3001 at the address P is stored in the cell buffer in which the congestion has occurred. Congestion notification RM as VPI and VCI assigned when the input cell is received
Notify the cell generation unit 6. As described above, the search of the VPI and VCI of the reception cell input to the congestion cell buffer in the cell buffer identifier / reception cell header information search units 5a and 5b is completed.

Next, the congestion notification RM cell generator 6 generates a congestion notification RM cell having VPI and VCI as headers. When the congestion notification RM cell is generated,
As shown in FIG. 4, the cell buffer identifier pair reception cell header information retrieval units 5a and 5b control the selectors 7a and 7b to switch the output to the congestion notification RM cell generation unit 6 side,
Transmission of cells from the cell buffer unit 2 is stopped, and the line 30
The congestion notification RM cell is transmitted via 0a2 and 300b2 to the source communication device of the cell that has caused the congestion.
When there is no congestion cell buffer, the above-mentioned operation of generating and transmitting the congestion notification RM cell is not performed, so that the selectors 7a and 7b are controlled by the cell buffer identifier / reception cell header information retrieval units 5a and 5b. The buffer unit 2 side is selected and the cells output from the cell buffer unit 2 are output to the interfaces 300a2 and 300b2 as transmission cells.

As described above, by using the ATM communication device of the present invention in the communication network, the cell causing the congestion can be transmitted faster and more reliably than the congestion control processing of the conventional communication network. Congestion can be notified to the existing communication terminal or communication device, and the amount of buffer provided in the communication device can be reduced.

FIG. 7 is a block diagram showing another structure of the ATM communication device having the congestion control function according to the present invention. The communication device 1010 is the communication device 100 described above.
In the configuration of 0, the congestion information display area 17-2 is also added as an in-apparatus cell shown in FIG. 5, the source of the cell in which congestion has occurred is identified by using this, and the RM cell is set as the source communication apparatus. And the congestion cell buffer identifier adding units 9a and 9b for adding the congestion information display area 17-2 to the in-device cell 17, and the congestion cell buffer for extracting the congestion cell buffer identifier from the congestion information display area 17-2. The identifier extraction units 10a and 10b are added.

The ATM communication device 1010, when performing header conversion by the header conversion units 1a and 1b, includes congestion of all cell buffers provided in the device, in addition to the header 100 of the in-device cell 17 and the routing information 17-1. Information display area 17-2
It is intended to process an in-apparatus cell provided with. When a certain cell buffer exceeds a preset threshold value of the number of accumulated cells in the buffer and becomes a congestion state, the congestion cell buffer detection unit 3 detects the congestion cell buffer, and the identifier of the cell buffer is the congestion cell buffer identifier notification unit 4 To all the congestion cell buffer identifier adding units 9a and 9b. The congestion cell buffer identifier adding units 9a and 9b store the congestion cell buffer identifiers in the congestion information display areas 17-2 of all in-device cells 17 output from the cell buffer unit 2. Specifically, as shown in FIG. 5, the congestion information display area 17-2 is provided in the in-apparatus cell header in a bit map type with a 1-bit area per cell buffer corresponding to the cell buffer identifiers of all the cell buffers. With the configuration, 0 is written in the bit position corresponding to the non-congested cell buffer and 1 is written in the bit position corresponding to the congested cell buffer in the congestion cell buffer identifier adding units 9a and 9b. For example, in a case similar to that described in the previous embodiment, since congestion occurs in the cell buffer n, 1 which means congestion occurrence is written in the bit position of n, and congestion occurs in other cell buffers. Since it has not occurred,
In the other bit positions corresponding to these buffers, 0 is written, which means that congestion has not occurred.

Congestion cell buffer identifier extraction unit 10a, 1
At 0b, the congestion cell buffer identifier is extracted from the input congestion information display area 17-2 of the in-device cell 17 and the cell buffer identifier / received cell header information retrieval units 5a and 5b are extracted.
To enter. Specifically, in the congestion cell buffer identifier extraction units 10a and 10b, the contents of the congestion information display area 17-2 of the in-device cell 17 are read, and it is determined whether each cell buffer is in the non-congestion state or the congestion state. The identifier of the cell buffer corresponding to the bit position where was written is output as the congestion cell buffer identifier. Cell buffer identifier vs. received cell header information search unit 5a, 5
In b, similar to the previous embodiment, the VPI and VCI assigned at the time of receiving the cell input to the congestion cell buffer are retrieved from the cell buffer identifier. The operation after the congestion cell buffer identifier is input to the cell buffer identifier / received cell header information search units 5a and 5b and the received VPI and VCI are searched is the same as in the previous embodiment.

FIG. 8 is a block diagram showing another structure of the ATM communication device having the congestion control function according to the present invention. The communication device 1020 is the communication device 101 described above.
The configuration of 0 uses the in-device cell 17 to which the congestion information display area 17-2 is added as a means for notifying the congestion cell buffer identifier to the cell buffer identifier pair reception cell header information retrieval units 5a and 5b, An in-device maintenance cell 18 for storing control information in the device is defined, and the identifier of the cell buffer in which congestion has occurred is utilized in the cell buffer identifier / received cell header information retrieval units 5a and 5b by utilizing the payload of this cell. It is a notification. FIG. 9 is a cell configuration diagram showing the configuration of the in-apparatus maintenance cell 18. The maintenance cell 18 includes a payload section 1 for storing maintenance information.
8-1 and a header 18-2 indicating a maintenance cell.

The ATM communication device 1020 has a maintenance cell 1
8 is used to notify the cell buffer identifier-reception cell header information search units 5a and 5b of the congestion cell buffer identifier to identify the source of the cell in which the congestion has occurred and send the RM cell to the source communication device. And the congestion cell buffer identifier adding unit 9 in the ATM communication device 1010.
In place of a and 9b, when the congestion of the cell buffer occurs, the congestion cell buffer identifier is stored in the payload section 18-1 of the maintenance cell 18 in the apparatus, and the maintenance cell inserting section 1 in the apparatus is stored.
Congestion cell buffer identifier extraction unit 1 including 1a and 11b
Instead of 0a and 10b, the congestion cell buffer identifier is read from the payload section 18-1 of the maintenance cell 18 and the cell buffer identifier / received cell header information retrieval sections 5a and 5 are read.
In-apparatus maintenance cell extraction units 12a and 12b to be input to b are added.

In this embodiment, the data structure for notifying the congestion cell buffer identifier in the payload 18-1 of the maintenance cell 18 has the same structure as the congestion information display area 17-2 described in the previous embodiment. In the in-device maintenance cell insertion units 11a and 11b, 0 is written in the bit position corresponding to the non-congested cell buffer in the payload 18-1 and 1 is written in the bit position corresponding to the congested cell buffer. In addition, in-apparatus maintenance cell extraction units 12a, 12
In b, the payload 18- of the input maintenance cell 18
The congestion cell buffer identifier is extracted from 1 and input to the cell buffer identifier-to-received cell header information retrieval units 5a and 5b. Specifically, the content of the payload 18-1 is read, it is determined whether each cell buffer is in the non-congested state or the congested state, and the identifier of the cell buffer corresponding to the bit position in which 1 is written is the congestion cell buffer identifier. Is output as. The cell buffer identifier-to-received cell header information retrieval units 5a and 5b retrieve the VPI and VCI assigned at the time of receiving the cell input to the congestion cell buffer from the cell buffer identifier, as in the previous embodiment. Cell buffer identifier vs. received cell header information retrieval unit 5
Congestion cell buffer identifier is input to a and 5b and received V
The operation after the PI and VCI are searched is the same as in the previous embodiment.

Hereinafter, another configuration of the cell buffer identifier / received cell header information retrieval units 5a and 5b, which is the retrieval unit of the cell transmission source communication device used in the ATM communication device of the present invention, will be described. Regardless of the configuration, the above A
It is applicable to the TM communication devices 1000, 1010, 1020.

FIG. 10 is a block diagram showing another configuration of the cell transmission source search unit (cell buffer identifier vs. received cell header information search unit 5) used in the ATM communication apparatus of the present invention. In the above embodiment, the table provided in the search unit is C
In contrast to the configuration of the AM 2001 and the RAM 3001, in the present embodiment, the table is configured only of the RAM 3002, and the cells input to the cell buffer in which congestion has occurred based on the cell buffer identifier, as in the previous embodiment. The VCI and VPI added at the time of reception are searched. As for the setting of the table, the connection setting unit 8 sets a table (not shown) of the header conversion units 1a and 1b according to an instruction from the user or a maintainer to establish the connection, as in the previous embodiment. At this time, the cell buffer identifier (routing information 17-1 in this embodiment) and the VPI and VCI of the reception cell are input to implement the configuration.

The storage area of the RAM 3002 is divided into an enable bit storage area and a reception cell header information storage area. Then, the address of the RAM 3002 is divided into blocks corresponding to the number of cell buffers, and the size of one divided block is the number C of combinations of VPI and VCI of the reception cells that can be input to one cell buffer. Configured to. Specifically, when the cell buffer identifier and the reception VPI and VCI data of the cell input to the cell buffer indicated by the cell buffer identifier are given to the RAM 3002, the value of the cell buffer identifier is multiplied by C. The VPI and VCI values of the reception cell are stored in the reception cell header information storage area whose value is an address, and the VPI and VCI of the reception cell stored in the reception cell header storage area are valid in the address enable bit storage area. In this configuration, the value 1 representing

When the cell buffer identifier / received cell header information searching unit 5 having the table configured as described above receives the congestion cell buffer identifier from the congestion cell buffer identifier notifying unit 4, the cell buffer identifier / received cell header information searching unit In 5, the value of the congestion cell buffer identifier is C
From the enable bit storage area whose address is the value obtained by multiplying to the enable bit storage area whose address is the value obtained by adding (C-1) to the address value, search the enable bit storage area by 1 within the search range. To the congestion notification RM cell generation unit 6 as the VPI and VCI of the reception cell input to the congestion cell buffer indicated by the congestion cell buffer identifier, the value stored in the reception cell header information storage area of the address Notice.

In a concrete example, for example, a user or a maintenance person performs header conversion on a received cell whose VPI is A and VCI is a, distributes and exchanges the received cell to a cell buffer whose cell buffer identifier is n, and outputs the cell to the line. When the connection setting unit 8 is instructed to establish such a connection, the connection VPI = A, VCI = from the connection setting unit 8 to the cell buffer identifier / reception cell header information searching units 5a and 5b.
a, cell buffer identifier = n is the communication path 800
a, 800b, and VPI = A, VCI = a in the received cell header information storage area at address nC.
, And 1 is stored in the enable bit storage area.
Here, when congestion occurs in the cell buffer whose cell buffer identifier is n, the congestion cell buffer identifier notifying unit 4 notifies the congestion cell buffer identifier = n, and the cell buffer identifier / received cell header information retrieving unit 5a, 5b The enable bit storage area from the address nC to the address nC + (C-1) is searched, and the data A and a stored in the received cell header information storage area of the address nC where the value 1 is stored is congested. The congestion notification RM cell generation unit 6 is notified of the VPI and VCI of the received cell input to the cell buffer. A such as RM cell generation and transmission after the search of the VPI and VCI of the reception cell input to the congestion cell buffer in the cell buffer identifier / reception cell header information retrieval units 5a and 5b according to the present embodiment is completed
The operation of the TM communication device is performed as in the above-described embodiment.

FIG. 11 is a block diagram showing another configuration of the cell transmission source search unit (cell buffer identifier / received cell header information search unit 5) used in the ATM communication apparatus of the present invention. In this embodiment, the table is configured only by the CAM 2003, and the VCI and VPI added at the time of reception of the cell input to the cell buffer in which congestion has occurred based on the cell buffer identifier as in the previous embodiment. It is a search. The table settings are the same as in the previous embodiment.
The connection setting unit 8 is a table (not shown) of the header conversion units 1a and 1b according to an instruction from a user or a maintenance person.
Cell buffer identifier (routing information 17-1 in this embodiment) when setting a connection and establishing a connection.
And the VPI and VCI of the receiving cell are input.

The storage area of the CAM 2003 is divided into a comparison and collation data storage area and an output data storage area.
A cell buffer identifier is stored as comparison and collation data in the comparison and collation data storage area, and VPI and VCI of the reception cell input to the cell buffer indicated by the cell buffer identifier are stored in the output data storage area.

The cell buffer identifier-to-received cell header information retrieval units 5a and 5b, which form the table as described above,
When the congestion cell buffer identifier is received from the congestion cell buffer identifier notifying unit 4, the comparison and collation data equal to the congestion cell buffer identifier is searched, and the value of the output data at the collation is indicated by the congestion cell buffer identifier. Of the received cell input to the cell buffer
It is read as I and VCI, and is notified to the congestion notification RM cell generation unit 6.

In a concrete example, for example, a user or a maintenance person performs header conversion on a received cell whose VPI is A and VCI is a, distributes and exchanges the received cell to a cell buffer whose cell buffer identifier is n, and outputs the cell to the line. When the connection setting unit 8 is instructed to establish such a connection, the connection VPI = A, VCI = a, from the connection setting unit 8 to the cell buffer identifier pair reception cell header information retrieval units 5a and 5b.
Information that the cell buffer identifier = n is the communication path 800a,
N via the CAM 2003 for comparison and collation, and VPI = A as the output data.
VCI = a is stored. Here, when congestion occurs in the cell buffer whose cell buffer identifier is n, the congestion cell buffer identifier notifying unit 4 notifies the congestion cell buffer identifier = n, and the cell buffer identifier-received cell header information retrieving unit 5a, 5b. The value n is searched for in the data storage area for comparison and collation. When the comparison and collation data n is detected, the data A and a stored in the output data storage area are used as the VPI and VCI of the received cell input to the congestion cell buffer, and the congestion notification RM cell generation unit 6 Will be notified.

Further, when a received cell having VPI of B and VCI of b is also header-converted and input to the cell buffer represented by the cell buffer identifier n, that is, VPI = A, VCI in one cell buffer. = A and VPI =
When a plurality of types of receiving cells of B and VCI = b are input, as shown in FIG. 11, first, when setting the table,
At the end of the output data storage area for storing VPI = A and VCI = a, where n is the data for comparison and collation, VPI = B, V
Q, which is comparison and comparison data in the output data storage area in which CI = b is stored, is stored. And VPI = B,
At the end of the output data storage area in which VCI = b is stored, data END indicating the search end position is stored.

Here, when congestion occurs in the cell buffer whose cell buffer identifier is n, the comparison and collation data n is detected in the same manner as in the above-described operation procedure, and A stored in the output data storage area, The data a and the data Q that indicates the next search position are first read.

When the comparison and collation data Q is subsequently detected in the comparison and collation data storage area, B and b stored in the output data storage area and E as the next retrieval position.
Since the ND is read and the next search position is END, the cell buffer identifier-received cell header information search unit 5
The search in a and 5b ends. After that, VPI =
A, VCI = a, VPI = B, and VCI = b are notified to the congestion notification RM cell generation unit 6 as the VPI and VCI of the received cell input to the congestion cell buffer. As described above, the cell buffer identifier pair reception cell header information retrieval unit 5a,
The search for the VPI and VCI of the received cell input to the congestion cell buffer in 5b is completed, and the following RM cell transmission operation is performed as described in the previous embodiment.

[0056]

According to the present invention, firstly, when the cell buffer is congested, the RM cell to which the congestion information is added is immediately notified to the communication terminal or the communication device which is sending out the cell which causes the congestion. It can be generated and transmitted in the communication device in which it occurs. Therefore, the communication terminal or the communication device can quickly know that the cell buffer is in a congestion state in the network.

Secondly, since it becomes possible for the communication terminal or the communication device to quickly know that the cell buffer is in the congestion state, from the occurrence of the congestion in the cell buffer until the communication terminal or the communication device lowers the cell transmission rate. Can be shortened, and the response of congestion control can be made faster.

Thirdly, since the response of the congestion control can be speeded up, the buffer amount prepared in the cell buffer can be reduced.

As described above, according to the present invention, the communication terminal or the communication device which is sending out the cell which causes the congestion in the congestion state of the cell buffer shortens the response time until the transmission cell speed is reduced. It is possible to provide an available service and an ATM communication device for realizing the service.

[Brief description of drawings]

FIG. 1 is a network configuration diagram showing a schematic configuration of an ATM communication network and a congestion control operation.

FIG. 2 is a cell configuration diagram showing the configuration of an ATM cell.

FIG. 3 is a network configuration diagram showing a schematic configuration and a congestion control operation of an ATM communication network of the present invention.

FIG. 4 is a block configuration diagram showing a configuration of an ATM communication device according to the present invention.

FIG. 5 is a cell configuration diagram showing a configuration of a cell used inside the ATM communication device.

FIG. 6 is a block diagram showing a configuration of a cell transmission source search unit according to the present invention.

FIG. 7 is a block diagram showing another configuration of the ATM communication device according to the present invention.

FIG. 8 is a block diagram showing another configuration of the ATM communication device according to the present invention.

FIG. 9 is a cell configuration diagram showing a configuration of a maintenance cell used inside an ATM communication apparatus according to the present invention.

FIG. 10 is a block diagram showing another configuration of the cell source search unit according to the present invention.

FIG. 11 is a block diagram showing another configuration of the cell transmission source search unit according to the present invention.

[Explanation of symbols]

1000, 1010, 1020: ATM communication device, 20
01, 2003: CAM, 3001, 300
2: RAM, 100a, 100b: line interface
200: switch unit, 300a1, 300b1: input interface, 300a2, 300b2: output interface, 400a, 400b: communication path, 501, 50
2, 503, 504, 505, 506: communication terminal, 70
0: Cell buffer, 800a, 800
b: communication path, 1a, 1b: header conversion unit,
2: cell buffer unit, 3: congestion cell buffer detection unit,
4: Congestion cell buffer identifier notifying unit, 5a, 5
b: cell buffer identifier-received cell header information retrieval unit,
6a, 6b: Congestion notification cell generation unit, 7a, 7b:
Selector, 8: Connection setting unit, 9a, 9b: Congested cell buffer identifier addition unit, 10a, 10b: Congested cell buffer identifier extraction unit, 11a, 11b: In-device maintenance cell insertion unit, 12a, 12b: In-device maintenance Cell extraction unit.

Claims (11)

[Claims] 1. Asynchronous transfer mode (Asyncrono)
(US Transfer Mode: hereinafter referred to as ATM) in an ATM communication device forming a communication network, in a cell buffer unit that temporarily stores cells, a congestion detection unit that detects a congestion state of the cell buffer, and a cell buffer unit. A source search unit that searches for a communication device that has input a cell, a congestion notification cell generation unit that generates a congestion notification cell that notifies the communication device that inputs a cell to the ATM communication device of the congestion of the cell buffer, and the cell An AT comprising: an output unit for transmitting the congestion notification cell to the communication device searched by the transmission source search unit when the buffer is congested.
M communication device. 2. An ATM communication device constituting an ATM communication network, comprising: a switch section having a cell buffer section for temporarily storing cells, a congestion detection section for detecting a congestion state of the cell buffer, and the cell buffer section. A source search unit that searches for a communication device that has input a cell, a congestion notification cell generation unit that generates a congestion notification cell that notifies the communication device that inputs a cell to the ATM communication device of the congestion of the cell buffer, and the cell An ATM communication device, comprising: a line interface unit having an output unit for transmitting the congestion notification cell to the communication device searched by the transmission source search unit when the buffer is congested. 3. An ATM communication device connected to an ATM communication network through an interface, comprising: a plurality of cell buffers for temporarily storing cells; a congestion detection unit for detecting a congestion state of the cell buffer; and a congestion detection unit A congestion cell buffer identifier notifying unit for notifying an identifier of a cell buffer in which congestion is detected, and a path identifier (VP) at the time of reception of a cell input from the identifier of the cell buffer into the cell buffer in which congestion is detected.
I) and the channel identifier (VCI), the cell source search unit, and the VP searched by the cell source search unit.
And a congestion notification cell generation unit that generates a congestion notification cell having I and VCI as headers, and an output unit that transmits the congestion notification cell to a communication device that has input a cell to the cell buffer in which the congestion is detected. Characteristic ATM communication device. 4. The cell transmission source search unit stores the VPI and VCI at the time of reception of a cell input to the cell buffer in a storage area whose head address is an identifier of each cell buffer of the plurality of cell buffers. When the congestion of the cell buffer occurs, the VPI and VCI at the time of reception of the cell input to the cell buffer in the congestion state are searched from the identifier of the cell buffer, and the searched VPI and VCI are the cells causing the congestion. The ATM communication device according to claim 3, wherein the VPI and VCI of the header of the congestion notification cell to be transmitted to the communication device transmitting 5. The cell transmission source search section stores data for comparing and collating cell buffer identifiers in the first memory and output data for outputting a pointer number assigned to each cell buffer identifier. A table comprising the first and second memories, which stores the VPI and VCI at the time of reception of the cell input to the cell buffer indicated by the cell buffer identifier with the pointer number as the address, When the congestion of the cell buffer occurs, the identifier of the cell buffer in which the congestion occurs is input to the table, the VPI and VCI at the time of reception of the cell input in the cell buffer in which the congestion occurs are searched, and the searched VPI and 4. The API according to claim 3, wherein the VCI is set to the VPI and VCI of the header of the congestion notification cell that is transmitted to the transmission source of the cell causing the congestion. TM communication device. 6. The congestion cell buffer identifier notifying unit provides a congestion information display area for all cell buffers in the headers of all cells processed in the ATM communication device, and outputs from the cell buffer when the cell buffer is congested. 4. The A according to claim 3, wherein a congestion cell buffer identifier is stored in the congestion information display area of a cell to be stored, and the cell source search unit is notified of the identifier of the cell buffer in which congestion has occurred.
TM communication device. 7. A maintenance cell for transmitting / receiving the internal state of the ATM communication device between functional blocks in the device is provided, and the congestion cell buffer identifier notifying unit is provided in the maintenance cell at the time of congestion of the cell buffer. 4. The ATM communication device according to claim 3, wherein a congestion cell buffer identifier is stored in the congestion information display area and the cell source search unit is notified of the identifier of the cell buffer in which congestion has occurred. 8. A congestion notification method for an ATM communication device constituting an ATM communication network, comprising: a first step of detecting a congestion state of a cell buffer that temporarily stores cells; and a cell in the cell buffer when congestion occurs. A second step of searching the input communication device; a third step of generating a congestion notification cell for notifying the communication device of the congestion of the cell buffer; and the communication device searched in the second step, A fourth step of transmitting a congestion notification cell, the congestion notification method for an ATM communication device. 9. A congestion notification method for an ATM communication device connected to an ATM communication network through an interface, comprising: detecting a congestion state of each of a plurality of cell buffers.
And a second step of notifying the device of an identifier of a cell buffer in a congestion state, a path identifier (VPI) and a channel identifier at the time of reception of a cell input to the cell buffer in which the congestion is detected from the identifier. A third step of retrieving (VCI), a fourth step of generating a congestion notification cell having the VPI and VCI in the header, and the congestion to a communication device that has input a cell to the cell buffer in which the congestion is detected. A fifth step of transmitting a notification cell, the congestion notification method for an ATM communication device. 10. An ATM communication network comprising a plurality of ATM communication devices and having a congestion control function, wherein each of the ATM communication devices detects a cell buffer section for temporarily storing cells and a congestion state of the cell buffer. A congestion detection unit, a transmission source search unit that searches for a communication device that has input cells to the cell buffer unit, and a congestion notification cell that notifies the communication device that inputs cells to the ATM communication device of the congestion of the cell buffer. A congestion notification cell generation unit for generating, an output unit for transmitting the congestion notification cell to the communication device searched by the transmission source search unit at the time of congestion of the cell buffer, and a cell transmission rate control unit, the communication network When detecting congestion in the cell buffer of any of the communication device, the communication device searches for other communication devices that input cells into the cell buffer where the congestion occurs, Transmits a congestion notification cell generated by the serial communication device to said another communication device, the other communication device receives the congestion notice cell,
An ATM communication network characterized by reducing a cell transmission speed to avoid a congestion state. 11. A congestion control method for an ATM communication network comprising a plurality of ATM communication devices, wherein each of the ATM communication devices comprises a first step of detecting a congestion state of a cell buffer for temporarily storing cells. A second step of searching for a communication device that has input a cell to the cell buffer when congestion occurs, a third step of generating a congestion notification cell for notifying the communication device of the congestion of the cell buffer, and the second step The fourth step of transmitting the congestion notification cell to the communication device found in step 5 and the fifth step of receiving the congestion notification cell to control the cell s When congestion is detected in the cell buffer, another communication device that has input cells to the cell buffer in which congestion has occurred is searched and a congestion notification cell is transmitted to the other communication device. Receiving device receives the congestion notification cell,
A congestion control method for an ATM communication network, characterized in that a cell transmission speed is reduced to avoid a congestion state.