JP2862709B2 - Bandwidth control device and bandwidth control method in ATM network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band control device and a band control method in an ATM network, and more particularly to a policing mechanism for monitoring whether a band of a cell transmitted on a communication path of the ATM network is maintained as declared. A bandwidth control device comprising:
It relates to a band control method .

In ATM (Asynchronous Transfer Mode) communication, since information such as variable-speed images and burst data is handled in addition to voice and data at a constant speed, it is very difficult for the network side to grasp the communication band. It is. Therefore,
Traffic that is larger than the instantaneously declared bandwidth may be input. As a result, the network may be overloaded and the service quality may be degraded (eg, cell discard).

In order to cope with such a problem, it is necessary to monitor the amount of traffic at the input section of the network and perform band control for performing some kind of regulation processing.

[0004]

2. Description of the Related Art FIG. In FIG. 8, reference numeral 80 denotes V included in the header of each cell of the input communication path.
CI (virtual channel number assigned to each call: Vi
VCI identification means for identifying a virtual channel identifier (RFC), reference numeral 81 denotes a cell passage counting means provided corresponding to each VCI number # 1 to #n, and reference numeral 82 denotes a band previously declared for a call corresponding to each VCI (for example, , A peak value), a report count holding means for holding the value of the number of cells (the number of cells in a given time), 83 a comparing means, 84 a logical sum means, 8
Reference numeral 5 denotes a disposal unit.

In operation, when cells of a plurality of calls are multiplexed and input on an input communication path, the VCI identification means 8
0, the VCI of each cell is identified and the identified VC
The outputs (VCI # 1 to #n) corresponding to I are generated. As a result, the cell passage counting means 81 counts for each VCI number to which the output is supplied. The comparing means 83 compares the count value (referred to as A) of the cell passage counting means 81 corresponding to each VCI within a predetermined time with the number of reports (referred to as B) set in the declared count holding means 82. And the value of A is B
Is exceeded, an output indicating the VCI is generated.
An instruction is provided to discard the cell with I. As a result, the discarding unit discards the cell having the corresponding VCI and does not transmit the cell to the output communication path.

Next, the configuration of the conventional example 2 shown in FIG. 9 will be described. In FIG. 9, 90 is a band monitoring means, 91 is a mark adding means, and 92 is an ATM network. This prior art 2 is called a marked cell method, and the bandwidth monitoring means 90
Converts the cells on the input communication path to the VCI
The number of arrivals within a certain period of time is counted every time, and when the number of arriving cells exceeds the declared value as compared with the declared value (input from the control unit) for each VCI, a mark adding means 91 that the corresponding VCI has been violated. To instruct. Thereby, the mark adding means 9
1 attaches a mark (for example, "1" is set to a predetermined specific bit in the header) to the cell having the corresponding VCI, and sends the cell to the ATM network 92. In the ATM network 92,
When congestion occurs in the network, a process for preferentially discarding the marked cells is performed.

[0007]

In the system of the prior art 1 described above, the number of cells arriving within a certain period of time is monitored, so that it can cope only with average traffic fluctuations, and the traffic increases instantaneously. In that case, there was a problem that control was impossible.

In the method of the second conventional example, in the case of a cell whose burstiness is instantaneously increased due to some influence despite the fact that the band is protected on average, the traffic characteristics of the cell output from the policing control unit are ATM because it does not change at all
There is a problem that cells are discarded in the network and service quality deteriorates.

The present invention provides a band control device and a band control method in an ATM network capable of controlling a cell whose traffic has increased instantaneously so as to reduce cell discard and not to exceed a declared band. The purpose is to:

[0010]

FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is a block diagram showing a first principle of read control means, and FIG. 3 is a block diagram showing a second principle of read control means.

In FIG. 1, 1 is a cell separating means for separating cells according to VCI, 2 is a cell storing means provided corresponding to each VCI, and 3 is the number of cells which can be stored in the cell storing means 2. The maximum cell storage amount setting means, 4 is a cell multiplexing means, and 5 is a read control means for reading cells from the cell storage means according to the declared band.

In FIGS. 2 and 3, reference numeral 20 denotes a selection number storage means, reference numeral 21 denotes a period counter, and reference numeral 22 denotes a random counter. According to the present invention, the cells of each VCI are stored in the cell storage means provided for each VCI. At this time, cells larger than the cell amount set in the maximum cell storage amount setting means are discarded, while each cell storage is discarded. The cells stored in the means are read out at a cycle corresponding to the declared bandwidth of each VCI.

[0013]

In FIG. 1, cells from an input communication path are input to a cell separating means 1 and separated according to a VCI number set in a cell header, and are stored in each cell storing means 2 corresponding to each VCI. You. Each cell storage means 2 is provided with a FIFO (Firs
t In First Out) type memory having a fixed capacity and storing the data, when the head cell of one cell storage means 2 selected by the cell multiplexing means 4 is read out, the other cell is read at the next timing. The cell storage means 2 is selected, and the first cell in the cell storage means 2 is read and multiplexed on the output communication path and output.

Reading is performed by reading control means 5,
Data corresponding to the declared bandwidth value declared in advance for each VCI (call) is set in the read control means 5 from a control unit (not shown). When a signal for selecting the storage means 2 is generated, a cell is read from the corresponding cell storage means 2.

As described above, by reading each cell storage means 2 at a period corresponding to each declared band according to each VCI, the cells of each VCI are placed on the output communication path at the speed within the declared band and at the same time. Burst-like cells can be smoothed and output.

In FIG. 1, a maximum cell storage amount setting means 3 is provided corresponding to each cell storage means 2. The maximum cell accumulation amount setting means 3 controls the cell accumulation amount by setting the number of cells (maximum value) which can be accumulated and stored in the cell accumulation means 2 according to the bandwidth declaration value declared for each VCI from the control unit. Used to make it possible. When the maximum value is supplied from the maximum cell storage amount setting means 3 to the cell storage means 2, the cell storage means 2
When the number of stored cells reaches the maximum value, no storage is performed even if more cells are input (cell discarding). For this reason, even if a large number of cells arrive instantaneously in a burst, it can be suppressed at this stage.

The first principle configuration of the read control means (5 in FIG. 1) shown in FIG. 2 will be described. The control unit writes the data of the VCI number (or the number of the cell storage unit 2) to each address of the selection number storage unit 20. This data is stored at addresses evenly spaced by the number proportional to the declared bandwidth of each VCI stored in each cell storage means 2. The selection number storage means 20 reads the count value of the cycle counter 21 as a read address, and supplies the read data to the cell multiplexing means 4. In this example,
Each address of the selection number storage means 20 is stored in the cycle counter 21.
Are read in the order of addresses.

Next, a second principle configuration of the read control means shown in FIG. 3 will be described. The selection number accumulating means 20 of FIG. 3 writes the data of the VCI number (or the number of the cell accumulating means 2) at each address from the control unit as in the first principle configuration of FIG. Optional (need not be evenly spaced). The address from which this data is read is generated from the random counter 22. Therefore, reading from the cell storage means 2 is performed in an order irrespective of the position of the write address of the selection number storage means 20.

[0019]

4 is a block diagram of the first embodiment, FIG. 5 is a block diagram of the second embodiment, FIG. 6 is a configuration example of a FIFO, and FIG. 7 is a diagram showing a portion of an ATM network to which the present invention is applied. .

In the configuration of the first embodiment shown in FIG.
It has a bandwidth of Mbps (megabit per second), and the VCI is the first on the input communication path (indicated by # 1)
Cell (declared bandwidth is 4 Mbps) and VCI is 4th (#
It is assumed that the cell of 4) (report bandwidth is 1 Mbps) is currently input.

In FIG. 4, reference numeral 40 denotes a VCI extraction unit;
Is a decoder, 42 is a FIFO (two-port memory for simultaneously performing writing and reading) which is provided for each VCI and is a buffer for cell storage, and 43 is a threshold of the cell storage amount (cell storage amount) corresponding to each FIFO. , A threshold setting unit for setting the maximum value of the cell, a selector 44 for multiplexing cells,
45 is a decoder, 46 is a RAM (Random Access Memory) storing data for controlling the selection operation in the selector.
ry) and 47 are 8-period counters. The RAM is 8
It has a data storage capacity corresponding to each address.

The operation of the embodiment shown in FIG.
VCI # 1 with a declared bandwidth of 4 Mbps on the ps input communication path
Of cells and a cell of VCI # 4 having a declared bandwidth of 1 Mbps are statistically multiplexed and sent to the input communication path. However, these cells do not always arrive in the same band as the declared value.

The VCI extracting section 40 extracts the VCI from the header of the cell on the input channel and identifies it in the decoder 41. According to the identification result of the decoder 41, the corresponding numbered FIFO 42 is written and driven, and the arriving cell is written into the corresponding FIFO 42, ie, FIFO # 1 and FIFO # 4.

For the FIFO 42 corresponding to each VCI,
When controlling the storage amount by setting the maximum storage cell amount, a threshold value is set in advance by a control unit (not shown) to the threshold setting unit 4.
Set to 3. This output is supplied to the corresponding FIFO 42, and each FIFO 42 performs an accumulation operation of the input cell within a range not exceeding its threshold value.

FIG. 6 shows a configuration example of the FIFO. To explain this operation, the cell input to the FIFO is written into the cell buffer when a write signal is supplied, the cell number counter 61 counts up (+1), the read signal is input, and one cell is input. When read, the cell number counter 61 counts down (-1). Accordingly, the count of the cell counter 61 indicates the number of cells stored in the cell buffer 60.

The count value of the cell number counter 61 is compared with a threshold value output from a threshold value setting unit (43 in FIG. 4) in a comparison circuit 62. When the counter value exceeds the threshold value, "0" is set. Is generated, otherwise "1" is generated. Therefore, the write signal of the cell buffer 60 is
The AND circuit 63 is supplied to the cell buffer when "1" is supplied from the comparison circuit 62, is not supplied to the cell buffer when it is "0", and the input cell is not written (discarded) at this time. .

The communication quality such as cell discard for input traffic characteristics is adjusted according to the threshold value set in the threshold value setting / setting section 43. For example, if the threshold is set higher, the cell discard rate for an instantaneous burst can be reduced.

Although one FIFO buffer is provided corresponding to one VCI in FIG. 6, actually one buffer is logically separated for each VCI and a plurality of buffers are provided. It is possible to adopt a configuration in which cells of VCIs are accumulated.

Returning to the description of FIG. 4, according to the declared bandwidths of 4 Mbps and 1 Mbps of VCI # 1 and VCI # 4, the address interval is made as uniform as possible as shown in FIG. A VCI number is assigned (written). That is, since the bandwidth of the cell of VCI # 1 is 4 Mbps, the bandwidth of the communication path is 8 Mbps, which is 1/1/4.
2 and 4 out of 8 addresses (A
DDR1, 3, 5, 7) are used, and the assignment is made every other address. Similarly, since the band of the cell of VCI # 4 is 1 Mbps, the band of the communication path is 8 Mbps, which is 1 / Mbps.
8, that is, one address (ADDR2) is allocated.

The RAM 46 is sequentially read using the counter value output from the eight-period counter 47 as an address, the VCI number read from the RAM 46 is identified by the decoder 45, and a read signal is output to the FIFO 42 corresponding to the number. On the other hand, the read VCI number is also supplied to the selector 44. The selector 44 selects the FIFO 42 from which the reading has been performed, and sends the read cell to the output communication path.

In this way, even if the arriving cells have bursty traffic characteristics and the number of cells arriving instantaneously increases, the declared bandwidth can be protected after reading from the FIFO, and the traffic can be further improved. Characteristics are smoothed.

The configuration of the second embodiment shown in FIG.
5 are the same circuits or devices as 40 to 46 in FIG. 4, respectively, and the description is omitted. Reference numeral 57 denotes an 8-cycle pseudo random number generation counter.

In the case of the second embodiment, the addresses of the RAM 56 are allocated to the RAM 56 in accordance with the instruction from the control unit at the ratio of the declared bandwidth of each VCI in the bandwidth of the communication path. At this time, unlike the case of the first embodiment, the way of allocating each VCI can be freely set to an empty address of the RAM 56.

The RAM 56 reads out the output of the 8-period pseudo random number generation counter 57 as an address, takes out the cell from the FIFO 52 of the outputted VCI number, and sends it to the output communication path. As a result, even if the arriving cell has bursty traffic characteristics, the declared bandwidth can be protected after reading from the FIFO 52, and the traffic characteristics are also smoothed.

Next, a portion of the ATM network to which the present invention is applied will be described with reference to FIG. FIG. Is a layout diagram of the central exchange, and a mechanism (for example, a policing mechanism) based on the bandwidth control system of the present invention can be provided at a position where an input communication path from a plurality of remote concentrators enters the exchange. In addition, FIG. The case (1) is a case where a mechanism is provided by a band control method of the present invention in a portion where each subscriber line is input in each remote line concentrator. Similarly, other VCs
The present invention can be applied to a portion for transmitting an I cell.

[0036]

According to the present invention, even if a cell whose traffic increases instantaneously occurs, the traffic characteristics after being output from the cell storage means are smoothed within the declared band (Traffic shap).
ing), control can be performed even when traffic increases instantaneously, and service quality such as cell discarding can be improved.

Further, when a network is set as a result of smoothing the traffic characteristics, the buffer amount can be reduced, which is economical. Further, by adding a maximum cell storage amount setting means for freely setting the queue length of the cell storage means provided for each VCI, even if a burst occurs in the input traffic characteristics, the amount of cell discard from the cell storage means is reduced. Can be adjusted.

[Brief description of the drawings]

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

FIG. 2 is a first principle configuration diagram of a reading control unit.

FIG. 3 is a second principle configuration diagram of a read control unit;

FIG. 4 is a configuration diagram of a first embodiment.

FIG. 5 is a configuration diagram of a second embodiment.

FIG. 6 is a configuration example of a FIFO.

FIG. 7 is a diagram showing a portion of an ATM network to which the present invention is applied.

FIG. 8 is a configuration diagram of Conventional Example 1.

FIG. 9 is a configuration diagram of a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cell separation means 2 Cell accumulation means 3 Maximum cell accumulation amount setting means 4 Cell multiplexing means 5 Read control means

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryuichi Takechi 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Co., Ltd. 56) References JP-A-2-170645 (JP, A) JP-A-4-336831 (JP, A) JP-A-6-6373 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) H04L 12/28 H04L 12/56

Claims (4)

(57) [Claims] 1. A method for identifying a call identification number of a received cell.
Identification means, cell storage means for reading received cells for each call identification number and storing them in a controllable manner, and reading of cells stored in the cell storage means for each call identification number
On the basis of the bandwidth information previously declared corresponding to the
A band control device in an ATM network, comprising : read control means for reading data from a cell storage means . 2. The system according to claim 1, wherein said cell storage means has a maximum storage amount setting means for setting a queue length that can be stored for each call identification number , and the input traffic is set based on a setting value of said maximum storage amount setting means. A bandwidth control device in an ATM network, wherein a cell discard amount in a cell storage unit when a burst occurs in characteristics is adjusted. 3. The method according to claim 1, wherein said cell storage means includes a plurality of files corresponding to call identification numbers.
A bandwidth control device in an ATM network, comprising a last-in first-out memory . The 4. A call identification number of the cell received from the channel
Identify and read the cell for each call identification number so that it can be controlled.
And stores the bandwidth identification information declared in advance corresponding to each call identification number.
Reading the cell from the memory on the basis of
Bandwidth control method in ATM network.