JP3027940B2 - Cell transmission / reception rate control method and cell assembly / disassembly module - Google Patents

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 for connecting to a network, and more particularly to a rate control method in cell assembly / disassembly and a cell assembly / disassembly module.

[0002]

2. Description of the Related Art A cell assembly / disassembly (hereinafter, CLAD) for transmitting / receiving data between an ATM network and a terminal by assembling / disassembling a cell.
It is called a module. )), When congestion occurs in the ATM network or the cell demultiplexing unit, the following congestion avoidance method is adopted. A method of avoiding congestion by temporarily stopping data transmission of a terminal, and a method of assembling cells transmitted from a transmitting terminal after performing cell assembly.
Cells are accumulated in a cell transmission buffer provided for each C (Virtual Circuit), and congestion control such as leaky bucket and shaping is performed by adjusting a reading interval from the cell transmission buffer, thereby delaying transmission timing and congestion. This is a way to avoid.

[0003]

The method of stopping data transmission from the terminal imposes a load on the buffer on the terminal side, and starts cell assembly of data at the time of resuming transmission, thereby reducing the efficiency of data transmission. In the method of accumulating the data in the cell transmission buffer after cell assembly and adjusting the read timing, the assembled cells need to be stored in the cell transmission buffer in VC units, so that data is continuously transmitted. It is necessary to prepare a cell transmission buffer having a sufficient capacity in anticipation of such a situation. Since the cell transmission buffer is provided for each VC, the buffer capacity becomes extremely large as a whole, and as a result, it is difficult to reduce the size and cost of the CLAD.

It is an object of the present invention to provide a cell transmission / reception rate control method and module which can effectively avoid congestion using a cell transmission buffer having a relatively small capacity.

[0005]

The present invention solves the above-mentioned problems by controlling the data transfer rate between a CLAD module and a terminal.

That is, the CLAD module according to the present invention converts transmission data from a transmission / reception terminal into cells and performs AT conversion.
In an ATM communication device that transmits data to the M network, converts received cells from the ATM network into received data, and transmits the data to the transmission / reception terminal, monitors whether congestion occurs in the ATM communication device or the ATM network; If congestion does not occur, set the transfer rate of transmission data to the sending and receiving terminal to a predetermined normal value, and if congestion occurs, set the transfer rate of transmission data to the sending and receiving terminal. It is set to a value lower than the normal value.

More specifically, when congestion does not occur, the transfer rate of transmission data is relatively high.
When congestion has occurred, the period of the transmission timing signal output to the transmitting and receiving terminal is controlled so that the transmission rate of the transmitting data is relatively low, and the transmission of the received data to the transmitting and receiving terminal is a predetermined transfer. The period of the reception timing signal output to the transmission / reception terminal is controlled so as to be the rate.

When congestion occurs from a state where congestion does not occur, transmission of transmission data is prohibited to a transmitting / receiving terminal in order to avoid data transmission during an unstable period of a clock, and a predetermined period is set. It is desirable to allow the transfer of the transmission data after the clock has stabilized after elapse.

[0009]

FIG. 1 is a schematic block diagram of an ATM communication apparatus using an embodiment of a CLAD module according to the present invention. The plurality of terminals 101 have a physical layer connected to the ATM communication device 102 via one of V35, RS449, and RS232C interfaces,
It is connected to the ATM network 103 via the ATM communication device 102. The ATM communication device 102 includes a plurality of terminals 101
And a plurality of CLAD modules 104 and a cell demultiplexing unit 105 respectively corresponding to Transmission data SD transmitted from a certain terminal 101 is converted into a cell by a corresponding CLAD module 104, and the cell demultiplexing unit 1
05 and multiplexed with cells from other CLAD modules and transmitted to the ATM network 103. Conversely, cells received from the ATM network 103 are separated for each channel by the cell demultiplexing unit 105, and the CL of the corresponding channel is
After being converted into the reception data RD by the AD module 104, it is transmitted to the corresponding terminal 101.

Each CLAD module 104 includes a CLAD unit 201 for disassembling and assembling cells, and an ATM communication device 1.
02, a congestion detection unit 202 for detecting congestion in the ATM network 103, a signal rate control unit 203 for adjusting transmission timing in accordance with a detection output of the congestion detection unit 202, and a control unit for outputting a control signal to the terminal 101 204. Further, the CLAD unit 201 includes a cell assembling unit 301 and a cell transmission buffer 302, and a cell reception buffer 303 and a cell decomposition unit 304.

The cell assembling section 301 includes the signal speed control section 20
3 according to the transmission timing signal ST2 from the terminal 101
The transmission data SD transmitted by the is input to assemble the cell. The formed cells are stored in the cell transmission buffer 302 and then read out to the cell demultiplexing unit 105 in accordance with a control signal from the control unit 204, where they are multiplexed and ATM multiplexed.
The data is transmitted to the network 103. The cell stream received from the ATM network 103 is separated for each VC by the cell demultiplexing unit 105 and stored in the cell reception buffer 303. The received cell is read out to cell decomposition section 304 according to the control signal from control signal control section 204,
Reference numeral 04 decomposes the received cell, converts it into a received data signal RD, and sends it to the terminal 101 according to the reception timing signal RT. The transmission timing signal ST2 and the reception timing signal RT generated by the signal rate control unit 203 are also output to the CLAD unit 201, and control the operation timing of the cell assembling unit 301 and the cell disassembling unit 304. Also,
The control signal control unit 204 outputs a control signal to the CLAD unit 201, outputs a transmission enable signal CS and a carrier detection signal CD to the terminal 101, and outputs a transmission request signal RS to the terminal 1
Input from 01.

As described above, the signal speed control unit 203 adjusts the transmission timing according to the detection output of the congestion detection unit 202. More specifically, in a normal state in which congestion is not detected, transmission is performed at a normal transmission timing, and in a state in which congestion is detected, the period of the transmission timing is lengthened, thereby lowering the cell transmission rate and reducing the congestion state. Maintain a low transmission rate until finished. Hereinafter, FIG.
An example of the transmission rate control method according to the present invention will be specifically described with reference to FIG.

FIG. 2 is a timing chart showing an example of the clock timing of the transmission timing signal ST2 and the reception timing signal RT, the transmission / reception data signal, and the control signal supplied by the signal speed control unit of the CLAD module. The terminal 101 and the CLAD module 104 are connected by any one of the V35, RS449, and RS232C interfaces, and the transmission timing signal S
The transmission and reception of the transmission data signal SD and the reception data signal RD are performed in synchronization with T2 and the reception timing signal RT, respectively.

In the normal state, the congestion detecting unit 202 does not detect congestion, so that the signal speed control unit 203 generates normal transmission timing signals ST2 and reception timing signals RT. In the normal state, when the terminal 101 performs data transmission, the terminal 101 first outputs a transmission request signal RS to the control signal control unit 204 of the CLAD module 104, and transmits a transmission enable signal CS from the control signal control unit 204. After the reception, the transmission data signal SD is output to the cell assembly section 301 of the CLAD section 201 in synchronization with the normal transmission timing signal ST2 received from the signal rate control section 203.

When detecting congestion in the ATM network 103 or the ATM communication device 102, the congestion detection unit 202 outputs a congestion detection signal to the signal rate control unit 203. When receiving the congestion detection signal, signal speed control section 203 lowers the clock frequency of transmission timing signal ST2. Terminal 1
1 outputs the transmission data signal SD in synchronization with the timing of the transmission timing ST2, so that when the congestion state is detected, the cell assembling rate of the cell assembling section 301 decreases,
The number of cells stored in the cell transmission buffer 302 per time decreases. In other words, the cell transmission buffer 30
2, the cycle of writing the transmission data cell and the cycle of transmitting the cell to the cell demultiplexing unit become longer in synchronization with the transmission timing ST2.

The transmission enable signal CS output from the CLAD module 104 in response to the transmission request signal RS output from the terminal 11 is, as shown in FIG.
03 is unstable while changing the transmission timing ST2.
Set to FF and turn on when the timing is stable.
This makes it possible to stably control the output timing of the transmission data signal SD.

On the other hand, when the terminal 101 performs data reception, the control signal control unit 204 of the CLAD module 104
Until the cell is received from the cell demultiplexing unit.
1 to turn off the carrier detection signal CD, and
When D section 201 receives a cell from the cell demultiplexing section, it turns on carrier detection signal CD for terminal 101 at the timing of outputting received data signal RD to terminal 101. Cell decomposition section 304 outputs received data signal RD to terminal 101 in synchronization with reception timing RT. By making the clock timing on the receiving side and the clock timing on the transmitting side independent, data can be received at a speed independent of the data transmission speed on the transmitting side. The delay caused by the data transfer rate control during cell transmission and the ATM network 10
The fluctuation of cell arrival due to the delay occurring in 3 is absorbed, and the cell disassembling section 304 can output the received data signal RD to the terminal 101 at a certain timing.

[0018]

As described above, the cell assembling / disassembling control method according to the present invention reduces the data transfer rate to the terminal when congestion is detected, thereby reducing the cell transmission buffer writing speed when performing cell assembly. Can be reduced. For this reason, it is possible to suppress congestion without increasing the transmission buffer capacity prepared for each VC unit.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an ATM communication device using one embodiment of a CLAD module according to the present invention.

FIG. 2 shows a transmission timing signal ST2 and a reception timing signal R supplied by a signal speed controller of the CLAD module.
5 is a timing chart illustrating an example of a clock timing of T, a transmission / reception data signal, and a control signal.

[Explanation of symbols]

 Reference Signs List 101 terminal 102 ATM communication device 103 ATM network 104 CLAD module 105 cell demultiplexing unit 201 CLAD unit 202 congestion detection unit 203 signal rate control unit 204 control signal control unit 301 cell assembling unit 302 cell transmission buffer 303 cell reception buffer 304 cell decomposition unit SD transmission data RD reception data ST2 transmission timing signal RT reception timing signal RS transmission request signal CS transmission enable signal CD carrier detection signal

Continuation of the front page (56) References JP-A-6-46394 (JP, A) JP-A-57-89356 (JP, A) JP-A-6-343077 (JP, A) JP-A-61-172459 (JP) JP-A-4-130838 (JP, A) JP-A-5-122238 (JP, A) Hiroshi Shimizu et al. "ATM-LAN", Soft Research, p. 123-126 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 11/28

Claims (5)

(57) [Claims] An AT which converts transmission data from a transmission / reception terminal into cells and transmits the cells to an ATM network, converts a reception cell from the ATM network into reception data and transmits the data to the transmission / reception terminals
The M communication device monitors whether or not congestion occurs in the ATM communication device or the ATM network. If the congestion does not occur, the transfer rate of the transmission data is relatively high. In the case where the congestion has occurred, a cycle of a transmission timing signal to be output to the transmitting / receiving terminal is controlled so that a transfer rate of the transmitting data is relatively low, and the receiving data is transmitted to the transmitting / receiving terminal. A method of controlling a cell transmission / reception rate, comprising: controlling a cycle of a reception timing signal output to the transmission / reception terminal so that the transmission is performed at a predetermined transfer rate. 2. When the congestion occurs from a state in which the congestion does not occur, the transmission of the transmission data is prohibited to the transmitting / receiving terminal, and the transmission of the transmission data is permitted after a predetermined period elapses. to the cell reception rate control method 請 Motomeko 1 wherein you characterized in that. 3. An AT for converting transmission data from a transmission / reception terminal into cells and transmitting the cells to an ATM network, and converting a reception cell from the ATM network into reception data and transmitting the data to the transmission / reception terminals.
In the M communication device, congestion detection means for detecting congestion occurring in the ATM communication device or in the ATM network, and when the congestion does not occur, a transfer rate of the transmission data is relatively high. A transmission control unit that controls a cycle of a transmission timing signal output to the transmission / reception terminal so that a transfer rate of the transmission data becomes relatively low when the congestion occurs; A cell assembling / disassembling module, comprising: a reception control means for controlling a period of a reception timing signal output to the transmission / reception terminal so that transmission to the terminal is performed at a predetermined transfer rate. 4. The physical network is connected to a transmitting / receiving terminal by one interface selected from V35, RS449, and RS232C, converts transmission data from the transmitting / receiving terminal into cells, and transmits the cells to an ATM network. An ATM communication device for converting a received cell from a received cell into received data and transmitting the received data to the transmitting / receiving terminal; a congestion detecting means for detecting congestion occurring in the ATM communication device or the ATM network; and an ATM network or an ATM communication device. Cell assembling means for reducing a clock cycle of a data transmission timing signal between the transmitting and receiving terminals when detecting congestion in the cell, thereby suppressing a transfer rate of transmission data from the transmitting and receiving terminals and adjusting a cell assembling speed. At the timing of cell reception, the transmitting / receiving terminal recognizes data reception, Cell disassembly means for outputting received data obtained by disassembling a received cell to a transmitting / receiving terminal in synchronization with a cell. 5. When the congestion occurs from a state in which the congestion does not occur, the transmission of the transmission data is prohibited to the transmitting / receiving terminal, and the transmission of the transmission data is permitted after a lapse of a predetermined period. The cell assembly / disassembly module according to claim 3 or 4, wherein