Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1998-12-28
2002-08-06
Chin, Wellington (Department: 2664)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S360000
Reexamination Certificate
active
06430156
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a traffic control method for providing a predictive/guaranteed service which can be widely employed for an exchanger of various communication systems, such as ATM, PSTN and IMT-2000, and in particular to a traffic control method for efficiently controlling a predictive/guaranteed service which can guarantee a quality of service QOS by controlling a transmission route according to properties of various traffic data with a policing function using a moving ceiling MC function and a packet scheduling function using a first in first out FIFO or weighted fair queueing WFQ method.
2. Description of the Background Art
In general, multimedia traffics transmitted/received in a communication system include traffics requiring a real-time property and an existence property at the same time, such as a control signal and a signalling data, and multimedia traffics such as a video traffic and an audio traffic, in addition to simple data.
The above-mentioned traffics are all mingled and transmitted through a single physical transmission route, and thus it is necessary to develop a method for dividing and transmitting the traffics pursuant to their properties.
That is to say, different qualities of service QOS are required in relation to the multimedia traffics. Therefore, in order to effectively support the multimedia traffics, the transmission route should be properly controlled according to their properties, and then the traffics should be transmitted therethrough.
The multimedia traffics are divided into a guaranteed service, a predictive service and a best-effort service by a degree of the consumers' satisfaction.
Here, in the case of the guaranteed service, the quality of service QOS should be satisfactory by 100%. A control-related data which should not lose a data falls under the guaranteed service. In the case of the predictive service, when a data is partially lost or a time is delayed, it can be restored. The audio traffic and video traffic are classified into the predictive service. The best-effort service implies a case that the quality of service QOS is not guaranteed and a data transmission is through a residual bandwidth.
The guaranteed service is required to completely satisfy the quality of service QOS. Thus, in order to guarantee it, an worst-case analysis should be carried out in relation to the performance of supported functions, and resources should be sufficiently assigned according to a result of the analysis.
Here, the worst-case analysis is performed by presuming that the traffics are driven at the same time, namely that each traffic is concentrated on a peak rate.
In the case of the predictive service, it should be considered to guarantee the quality of service QOS and to efficiently use the resources. That is, a necessary quality of service should be guaranteed by efficiently using a small volume of resources. It is not preferable to completely guarantee the quality of service QOS by consuming a large volume of resources.
On the other hand, in order to support the predictive/guaranteed service, intermediate nodes on a network should perform various functions, such as routing, resource reservation, call admission control, packet scheduling and policing. The routing, resource reservation and call admission control functions are necessary before calls are set, and the packet scheduling and policing functions are employed while a packet data is transmitted after the calls are set.
The packet scheduling function serves to determine on which input route a packet to be-transmitted next is positioned by operating in packet units, and to intercept the other input routes. The packet scheduling function supports a packet-level isolation.
Here, the policing function serves to observe each route whether packets are transmitted according to properties described in a traffic describer, and to control the route which does not transmit the packets pursuant to the properties to abandon the packets.
A maximum transmission rate (interval between the packets) and an average transmission rate (a number of the packets averagely transmitted for a predetermined period) are mainly observed by the policing function. When observing the average transmission rate, the policing function determines after observation for a predetermined time, and supports a call-level isolation.
Here, the call-level isolation implies a case that, although one route transmission rate is temporarily increased, an average transmission rate of the other routes is not reduced. That is, the quality of service QOS is influenced not by a volume or pattern of packets transmitted through the other routes but by a volume or pattern of packets transmitted through its own route.
According to the conventional art, as illustrated in
FIG. 1
, a cell traffic control circuit and a method thereof (Patent Publication Gazette Heisei 8-79251) which was applied for registration on Aug. 30, 1994, includes: a cell detecting unit
12
for detecting an input of a cell on an input line, a kind of the inputted cell and a frame discriminator displayed on a corresponding cell; a traffic observing unit
16
computing a number of frames (n) which are being transmitted through an output line and a number of frames (m) which are being transmitted in a circuit by each band managing unit (w); a frame buffer unit
14
having a frame buffer with a plurality of sides for accumulating cells composing a corresponding frame in frame units when the frames are inputted over a predetermined maximum frame number; an empty frame buffer managing unit
15
for managing an empty frame buffer in the frame buffer unit
14
; and a frame transmission control unit
13
for determining to accumulate the inputted cell in the frame buffer unit
14
or to transmit the cell through the output line. The frame transmission control unit
13
has a frame accumulation and registration table
13
a
with the frames which are being accumulated and a value of the band managing unit (w). When the band managing unit in which the inputted cell detected by the cell detecting unit
12
is included is registered on the frame accumulation and registration table
13
a
, the corresponding cell is accumulated in the frame buffer unit
14
. When the cell is not registered thereon, if the corresponding inputted cell is an intermediate cell or final cell composing an information frame, the cell is transmitted to the output line. In the case that the cell is a first cell or single cell, it is determined by a predetermined determination rule whether the cell is transmitted to the output line or accumulated in the frame buffer unit
14
.
According to the method for controlling the cell traffic, a number of the traffics which can be transmitted through the line is set to be a maximum frame number (N) which can be simultaneously transmitted. There are provided a unit for computing a number of the frames (n) which are being transmitted through the line and a buffer for accumulating the cells composing a corresponding frame when the frames are inputted over the maximum frame number. When the cell is a valid cell and a first cell or single cell composing the information frame, in case ‘n’ is smaller than ‘N’ (n<N) at the time of the cell arrival, a series of cells included in an identical frame to the corresponding cell are transmitted through the output line, and in case ‘n’ is equal to ‘N’ (n=N), a series of cells included in an identical frame to the corresponding cell are accumulated in the buffer discriminating the frame. In relation to the frame accumulated in the buffer, the cell traffic on the output line is controlled within a predetermined range by reading the cell from the buffer unit and transmitting it through the line within the range of ‘n≦N’ in the case that the input cell is not an invalid cell such as an empty cell, or the input cell is accumulated in the buffer and not transmitted through the output line.
The above-described conventional method relates to the policing function i
Hwang Woon-Hee
Kwak Jin-Kyu
Oh Se-Jong
Park Jae-Hong
Yang Shin-Hyun
Chin Wellington
Hyundai Electronics Inds Co Ltd.
Lackenbach Siegel
Nissen J. Harold
Pham Brenda
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