Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
TITLE OF THE INVENTION
TRAFFIC CONTROL UNIT AND TRAFFIC CONTROL METHOD
TECHNICAL FIELD
The present invention relates to a traffic control
unit and a traffic control method in data transmission such
as cell transmission in asynchronous transfer mode (ATM)
l0 network. More particularly, it relates to a traffic
control unit and a traffic control method capable of
preventing shared resources in a network from being wasted
by positively carrying out the traffic control in the right
place in the network. In addition, it relates to a traffic
control unit and a traffic control method capable of
achieving, for data that take place in a burst mode at a
period proper to the data, appropriate control by selecting
a traffic monitoring period with taking account of the
proper period.
2o
BACKGROUND ART
It is said that a major object of the traffic control
in a BISDN (Broadband Integrated Services Digital Network)
is to protect networks and users for achieving
predetermined performance targets of the network, such as
cell delay variations (refer to ITU-T Recommendation I .371,
"Traffic control and congestion control in B-ISDN" ) . The
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traffic control basically refers to a series of processings
carried out by the network for avoiding congestion, and
has functions for optimizing the usage of the resources
in the network (network resources) to optimize the
efficiency of the network. To implement such functions,
a connection admission control (CAC) function and a usage
parameter control (UPC) function are defined as functions
for managing and controlling the traffic of an ATM network.
The connection admission control (CAC) is defined as
a series of processings carried out by the network in the
call setup stage. An ATM transmission system provides
quality assurance of the communication connection, and to
achieve this, traffic condition of the communication
connection is exchanged between the user and the network
at the communication initialization. In this case, it is
necessary for the user and network to conduct negotiations
and establish an accord on the information (such as
declared parameter like traffic parameter) that is
contained in a traffic contract specification. On the
basis of the declared parameter and taking account of the
used state of the network resources, the network side
decides on whether it accepts the user communication or
not. This processing is called connection admission
control (CAC).
The usage parameter control (UPC) is carried out in
a user network interface ( UNI ) , and refers to a series of
processings the network carries out for monitoring and
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controlling the traffic on the ATM connection from the view
point of the traffic volume of cells or the like. When
the network allows the user to start communication, the
communication enters a traffic state. In the traffic
state, the network carries out traffic monitoring
(policing) of user cells in accordance with the declared
parameter. The usage parameter control (UPC) function is
provided as a concrete method for implementing the policing.
The UPC function carries out the following functions when
to the number of input cells exceeds the value defined by the
declared parameter: l.smoothing; 2.ce11 discard; and
3.violation display and the like. On the other hand, to
meet the declared traffic condition (traffic parameter),
the user terminal side carries out traffic shaping (TS)
control that transmits burst traffic exceeding the
declared value by averaging it.
The declared parameter includes peak cell rate ( PCR ) ,
sustainable cell rate ( SCR ) , maximum burst size ( MBS ) and
the like, which are standardized in the ATM forum or ITU
-T , and known worldwide ( see , ITU-T Recommendation I . 371 ,
"Traffic control and congestion control in B-ISDN" ) . When
controlled data are not limited to cells, the term
"traffic" is used in place of "cell" such as a peak traffic
rate (PTR) and sustainable traffic rate ( STR).
The UPC function of the foregoing network, which is
assigned in a conventional fixed network to an input port
of subscriber's lines in a local switch, discards illegal
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traffic taking place when a user transmits over the
declared traffic.
Fig. 11 is a diagram showing a configuration in which
a UPC unit and a TS unit are installed in a conventional
fixed network. As shown in Fig. 11, a user terminal side
from an ATM terminal 900 up to a local (ATM) switch 930
includes a private optical fiber and the like 910 installed
for respective subscribers (users). Even if traffic
beyond the declared parameter takes place, it does not
present any problem to other users when a UPC unit 920 is
installed before an input port of the local ATM switch 930
whose resources are shared with other users to carry out
the traffic control ( UPC control ) . In contrast with this ,
a TS unit 905 is installed on the user terminal side so
that burst mode traffic beyond the declared value is
transmitted after averaging it to meet the declared traffic
condition.
However, the mobile communications, whose
configuration differs from that of the conventional fixed
network as shown in Fig. 11, shares resources such as radio
resources and base station transmission paths with other
users in the section from the user terminals to the local
switch . Therefore , when carrying out the traff is control
such as discarding the illegal traffic in the local switch
as in the foregoing fixed network, the shared resources
such as the radio resources and base station transmission
paths associated with the discarded traffic are wasted.
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This presents a problem of being inefficient. The same
problem arises when applying shared resources such as
multiplex transmission paths (for example, a network
comprising a LAN (Local Area Network) and PBX (Private
Branch Exchange)) tosubscriber access transmission paths.
On the other hand, when carrying out the traffic control
in unshared resources in the network such as user terminals ,
for example, there is apprehension that the traffic control
can become lax because of user' s modifications regardless
of whether malicious or not. Accordingly, it is
preferable that the traffic control be carried out in the
shared resources in the network out of users' reach, before
the shared resources are used for the data transmission.
Fig. 12 is a diagram illustrating an example of the
conventional traffic control. The control as shown in Fig.
12 carries out a processing for deciding the exceeding
cells as non-conforming cells, when the cumulative data
transmission volume in a cell monitoring period (8 [cell
times]) exceeds an allowed transmission volume (3 [cells])
based on the cell rate (3 /8 [celljcell time]). In the
example of Fig. 12, the seventh cell is decided as a
non-conforming cell. The cell which is decided as a
non-conforming cell is discarded, for example. As the
cell rate, a PCR or SCR is available.
However, the conventional traffic control has a
problem of being unable to achieve appropriate control for
such data as taking place in a burst mode at a period proper
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to the data because the conventional traffic control does
not select a traffic monitoring period with considering
the proper period. For example, consider a case in a mobile
radio network, in which a radio base station assembles ATM
cells from radio frames sent from mobile stations, and
carries out the traffic control of the generated ATM cells
(data). When generating the ATM cells from the radio
frames, particularly when generating a plurality of ATM
cells from one radio frame, the ATM cells are generated
to in a burst mode at every radio frame period. In this case,
burst traffic takes place at every radio frame period, and
a lot of data are discarded as data that cannot meet the
traffic condition when the traffic monitoring period is
selected unsuitably ( for example , when it is much smaller
than the radio frame period). This is because the PCR at
the radio base station becomes much larger than the PCR
at the input to the mobile station side, because the PCR
(PTR) decided by the traffic control unit is the reciprocal
of the cell interval. Thus, it is preferable that the
traffic control be carried out by selecting an appropriate
traffic monitoring period with considering the period
proper to the data to be subjected to the control (for
example, the radio frame period).
DISCLOSURE OF THE INVENTION
The present invention :is implemented to solve the
foregoing problems. Therefore, an object of the present
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invention is to prevent the waste of the shared resources
in the network by positively carrying out the traffic
control in an appropriate p:Lace in the network.
Another object of the present invention is to provide
appropriate control for data occurring in a burst mode at
the period proper to the data by selecting traffic
monitoring period with considering the proper period of
the data.
In order to accomplish the objects aforementioned,
according to the invention as claimed in claim 1, a traffic
control unit for carrying out traffic control of data in
a first shared resource of a network including besides the
first shared resource, a second shared resource and a local
switch, which are shared by a plurality of users,
comprises:
receiving means for receiving the data;
traffic control means for carrying out traffic control
of data to be transmitted to the local switch through the
second shared resource from among the data received by the
receiving means; and
transmission means for transmitting the data passing
through the traffic control by the traffic control means.
According to the invention as claimed in claim 2, in
the traffic control unit as claimed in claim 1, the network
comprises:
a radio base station; and
a transmission path between the radio base station and
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local switch for transmitting data between the radio base
station and the local switch, and wherein
the first shared resource consists of the radio base
station, and the second shared resource includes the
transmission path between the radio base station and local
switch.
According to the invention as claimed in claim 3, in
the traffic control unit as claimed in claim 1 or 2, the
data takes place in a burst mode at a period proper to the
l0 data, and wherein the traffic control unit carries out,
for the data received by the receiving means, traffic
control such that a cumulative transmission volume in a
traffic monitoring period defined by taking account of the
proper period does not exceed a volume based on a traffic
rate.
According to the invention as claimed in claim 4, a
traffic control unit for carrying out traffic control of
data taking place in a burst mode at a period proper to
the data, comprises:
receiving means for receiving data;
traffic control means for carrying out traffic control
for the data received by the receiving means such that a
cumulative transmission volume in a traffic monitoring
period defined by taking account of the proper period does
not exceed an allowed transmission volume based on a
traffic rate; and
transmission means for transmitting data controlled
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by the traffic control means.
According to the invention as claimed in claim 5, in
the traffic control unit as claimed in claim 4, the traffic
control means carries out, for the data received by the
receiving means, peak traffic control such that a
cumulative transmission volume i.n a peak traffic
monitoring period defined by taking account of the proper
period does not exceed an allowed transmission volume based
on a peak traffic rate, and sustainable traffic control
l0 such that a cumulative transmission volume in a sustainable
traffic monitoring period defined by taking account of the
proper period does not exceed an allowed transmission
volume based on a sustainable traffic rate.
According to the invention as claimed in claim 6, in
the traffic control unit as claimed in claim 5, the
sustainable traffic control is carried out by sliding the
sustainable traffic monitoring period at every peak
traffic monitoring period.
According to the invention as claimed in claim 7, in
the traffic control unit as claimed in claim 5 or 6, the
peak traffic control period is equal to the proper period,
and the sustainable traffic control period is equal to n
times the proper period, where n is a natural number.
According to the invention as claimed in claim 8, in
the traffic control unit as claimed in any one of claims
4-7, the data consists of ATM cells generated from a radio
frame, and the proper period equals a radio frame period.
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According to the invention as claimed in claim 9, a
traffic control method for carrying out traffic control
of data in a first shared resource of a network including
besides the first shared resource, a second shared resource
and a local switch, which are shared by a plurality of users,
comprises the steps of:
receiving data;
carrying out traffic control of data to be transmitted
to the local switch through the second shared resource from
among the data received; and
transmitting the data passing through the traffic
control.
According to the invention as claimed in claim 10, a
traffic control method for carrying out traffic control
of data taking place in a burst mode at a period proper
to the data, comprises the steps of:
receiving data;
carrying out traffic control of the data received such
that a cumulative transmission volume in a traffic
monitoring period defined by taking account of the proper
period does not exceed an allowed transmission volume based
on a traffic rate; and
transmitting data passing throug h the traffic
control.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram showing a configuration of
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a traffic control unit of a first embodiment in accordance
with the present invention;
Fig. 2 is a block diagram showing a configuration in
which the traffic control unit of the first embodiment in
accordance with the present invention is installed in a
network including a LAN and PBX;
Fig. 3 is a block diagram showing a configuration in
which the traffic control unit of the first embodiment in
accordance with the present invention is installed in a
mobile radio network comprising mobile stations and a radio
base station;
Fig. 4 is a block diagram showing a configuration in
which the traffic control unit of the first embodiment in
accordance with the present invention is installed in a
network comprising another network and a gateway switch;
Fig. 5 is a block diagram showing a configuration of
the traffic control unit of a second embodiment in
accordance with the present invention;
Fig. 6 is a block diagram showing a mobile radio
network in which the traffic control unit of the second
embodiment in accordance with the present invention is
installed;
Fig. 7 is a flowchart illustrating a control
processing by the traffic control unit of the second
embodiment in accordance with the present invention;
Fig. 8 is a diagram illustrating an example to which
the traffic control processing of Fig. 7 is applied to cells
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transmitted;
Fig. 9 is a flowchart illustrating another control
processing by the traffic control unit of the second
embodiment in accordance with the present invention;
Fig. 10 is a diagram illustrating an example to which
the traffic control processing of Fig. 9 is applied to cells
transmitted;
Fig . 11 is a diagram showing a configurat ion in which
a UPC unit and a TS unit are installed in a conventional
fixed network; and
Fig. 12 is a diagram illustrating an example of
conventional traffic control.
BEST MODE FOR CARRYING OUT THE INVENTION
The embodiments in accordance with the present
invention will now be described with reference to the
accompanying drawings.
[FIRST EMBODIMENT]
2U Fig. 1 is a block diagram showing a configuration of
a traffic control unit of a first embodiment in accordance
with the present invention. A traffic control unit 10 of
the present embodiment comprises a receiver 12, a traffic
controller 14 and a transmitter 16. The traffic
controller 14 carries out the traffic control of the data
received by the receiver 12. Although the data
unconformable to the traffic condition (declared
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parameter) of the traffic control is discarded in the
present embodiment, the data transmission can be regulated
to meet the traffic condition by installing a buffer. The
transmitter 16 transmits the data, which undergoes the
traffic control. Although the traffic controller 14 is
implemented in the form of hardware in the present
embodiment, it can be implemented by means of software.
Fig . 2 is a block diagram showing an example in which
the traffic control unit of the present embodiment is
l0 installed in the network including a LAN and PBX. Data
transmitted from an ATM terminal 100, 105 or 110 is
transmitted to a local switch 170 through a LAN 140 and
PBX 160. The LAN 140 and PBX 160 are connected through
a transmission path between LAN and PBX, which enables data
transmission. Besides, the PBX 160 is connected to the
local switch 170 through a transmission path between PBX
and local switch, which enables the data transmission
between them.
In Fig. 2, a traffic control unit 10 is installed on
2.0 the transmission path between the LAN and PBX. This makes
it possible to prevent the PBX 160 and transmission path
between the PBX and local switch, which are the shared
resources, from being wasted. Furthermore, as for the
transmission path between the LAN and PBX, which is another
shared resource, the waste thereof can be prevented from
the traffic control unit 10 up to the PBX 160. In addition,
since the traffic control is carried out in the
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transmission path between the LAN and PBX, which are shared
resources, the possibility that a user loosens the traffic
control is small.
Alternatively, the traffic control unit 10 can be
installed in the LAN 140, PBX 160 or transmission path
between the PBX and local switch, which are the shared
resources.
Fig. 3 is a block diagram showing an example, in which
the traffic control unit of the present embodiment is
applied to a mobile radio network comprising mobile
stations and a radio base station. Data sent from an ATM
terminal 200 or 210 is transmitted to a local switch 270
through a mobile station 240 or 245 and a radio base station
250. The mobile stations 240 and 245 and the radio base
station 250 carry out data transmission by means of radio
communications. In addition, the radio base station 250
and the local switch 270 are connected through a
transmission path between the radio base station and local
switch to perform data transmission.
In Fig. 3, the traffic control unit 10 is installed
in the radio base station 250. This makes it possible to
prevent the transmission path between the radio base
station and local switch, which are shared resources , from
being wasted . Besides , the radio base station 250 , which
is one of the shared resources, can also avoid a waste
processing of the data discarded by the traffic control.
Moreover, since the radio base station 250, which is one
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of the shared resources , carries out the traff is control ,
the possibility that the user loosens the traffic control
is small.
Incidentally, the traffic control unit 10 can also be
installed on the transmissian path between the radio base
station and local switch, which belong to the shared
resources.
Fig. 4 is a block diagram showing a configuration in
which the traffic control unit of the present embodiment
is installed in a network comprising another network and
a gateway switch. Another network 430 (a partial network
seen from the entire network) in a non-ATM section 440 is
a network to which an Internet services provider (ISP)
provides connection , for example . In this case , when the
ISP does not support the traffic control, it will be
possible that burst mode traffic beyond the declared
traffic volume can take place depending on the traffic
condition at the user terminal. Accordingly, the
effective usage of the resources in the network can be
achieved by shaping the traffic within the declared value
defined in advance by the traffic control unit 10 installed
between the another network 430 and gateway switch 410.
The data transmitted from the another network 430 is
transferred to the local switch 470 through the gateway
switch 410. The another network 430 is connected with the
gateway switch 410 through the transmission path between
the another network and gateway switch, which enables the
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data transmission. In addition, the gateway switch 410
and local switch 470 are connected through the transmission
path between the gateway switch and local switch, which
enables the data transmission.
In Fig. 4, the traffic control unit 10 is installed
on the transmission path between the another network and
gateway switch. This can prevent the gateway switch 410
and transmission path between the gateway switch and local
switch, which are the shared resources, from being wasted.
Besides, on transmission path between the another network
and gateway switch, which is one of the shared resources,
the waste of the part from the traffic control unit 10 up
to the gateway switch 410 can be prevented. Moreover,
since the traffic control is carried out between the
another network and the gateway switch, which belong to
the shared resources , the possibility that the user loosens
the traffic control is small.
Incidentally, the traffic control unit 10 can also be
installed in the gateway switch 410 or on the transmission
path between the another network and gateway switch, which
are the shared resources.
Thus carrying out the traffic control positively in
an appropriate position in the network as in the present
embodiment can prevent the shared resources in the network
from being wasted.
[SECOND EMBODIMENT]
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Fig. 5 is a block diagram showing a configuration of
a traffic control unit of a second embodiment in accordance
with the present invention. Like the traffic control unit
of the first embodiment, a traffic control unit 60 of
5 the present embodiment comprises a receiver 62 , a traffic
controller 64 and a transmitter 66. Although the traffic
controller 64 is implemented in the form of hardware in
the present embodiment, it can be implemented by means of
software. The traffic controller 64 carries out peak
10 traffic control and sustainable traffic control as will
be described below.
Fig. 6 is a block diagram showing a mobile radio
network, in which the traffic control unit of the present
embodiment is installed in the radio base station of the
mobile radio network as in Fig. 3 to carry out the traffic
control of ATM cells (data) consisting of radio frames.
Installing the traffic control unit 60 in the radio base
station 650 enables the traffic control to be achieved
positively, and to prevent the shared resources in the
network from being wasted as described in connection with
the first embodiment.
Data transmitted from an ATM terminal 600 or 610 is
transmitted to the radio base station 650 through a mobile
station 640 or 645. The radio base station 650 generates
ATM cells from radio frames, and carries out the traffic
control of the generated ATM cells by the traffic control
unit 60. The ATM cells subjected to the traffic control
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are transmitted to a local switch 670.
Fig. 7 is a flowchart illustrating a control
processing of the traffic control unit of the present
embodiment . In Fig. 7 , TPCR denotes a peak cell ( traffic )
monitoring period, which is equal to the radio frame period
in the present embodiment . This makes it possible to avoid
discarding much of the ATM cells that are generated in a
burst mode . TscR designates a sustainable cell ( traffic )
monitoring period, which is equal to n times the radio frame
period (= TPCR) in the present embodiment, where n is a
natural number. XPCR denotes an allowed transmission
volume based on PCR, that i_s, the number of cells
transmittable in the peak cell monitoring period. XscR
denotes an allowed transmission volume based on SCR, that
is, the number of cells transmittable in the sustainable
cell monitoring period. CPC, and CscR are a counter of the
number of cells, each.
As the traffic control processing, at step 5101, the
counters CPCR and CscR are cleared to zero and the monitoring
periods TPCR and TscR are reset , first . Then, it enters the
idle state at step S102. When a cell input takes place,
a decision is made at step 5103 as to whether the new input
of the cell causes the cumulative cell transmission volume
( the cell number counter ) (:PCR i_n the current peak cell
monitoring period to exceed the allowed transmission
volume XPCR. If exceeding, the new input cell is decided
as a non-conforming cell at step 5104. If not exceeding,
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a decision is made at step S105 as to whether the new input
of the cell causes the cumulative cell transmission volume
CscR in the current sustainable cell monitoring period to
exceed the allowed transmission volume XSCR or not. If
exceeding, the new input cell is decided to be a non-
conforming cell at step 5104. If not exceeding, the new
input cell is decided as a conforming cell at step 5106,
and the CPCR and CSCR are incremented by one at step 5107.
After deciding the conformance/non-conformance of the
new input cell, the processing returns to the idle state
at step 5102, at which a decision is made as to whether
the peak cell monitoring period TPCR is completed or not,
and proceeds to step 5108 when completed. The decision
of the completion is made even if the cell input does not
take place . At step 5108 , a decision is made as to whether
the sustainable cell monitoring period TSCR is completed,
and if completed, the processing returns to step 5101. If
not, the processing proceeds to step 5109, to clear the
CPCR to zero, and reset the T~,cFt, thus returning to step S102.
Fig. 8 is a diagram illustrating an example that
applies the traffic control. processing of Fig. 7 to the
new cell transmitted. In Fig. 8, it is assumed that TPCR
= 4 [ cell time ] , TSCR = 16 [ cell time ] ( n = 4 ) , XPCR = 2 [ cells ] ,
and XSCR = 5 [ cells ] . When applying the control processing
to the cells transmitted, t:he CPCR and CSCR vary as shown
in Fig. 8, and the cells at the seventh and 14th cell times
are decided as a non-conform cell because of XPCR < CPCa +
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1 , and Xsck < CscR + 1 , respectivly.
Fig. 9 is a flowchart illustrating another example of
the control processing by the traffic control unit in the
present embodiment. The control processing carries out
the sustainable traffic control by sliding the sustainable
traffic monitoring period at every peak traffic monitoring
period. The symbols TPCR, TscR and the like are the same as
those of Fig. 7.
As the traffic control processing, at step 5201, the
l0 counters CPCR and NscR are cleared to zero and the monitoring
periods TPCR and TscR are reset , first . Then, the processing
enters the idle state at step S202. When a cell input takes
place, a decision is made at step S203 as to whether the
new input of the cell causes the cumulative cell
transmission volume CF,cR in the current peak cell monitoring
period to exceed the allowed transmission volume XPCR. If
exceeding, the new input cell is decided as a non-
conforming cell at step 5204. If not exceeding, a decision
is made at step 5205 as to whether the addition of the new
input cell causes the cumulative cell transmission volume
NscR in the current sustainable cell monitoring period to
exceed the allowed transmission volume XscR or not. If
exceeding, the new input cell is decided to be a non-
conforming cell at step 5204. If not exceeding, the new
input cell is decided as a conforming cell at step 5206,
and the CPCR and NscR are incremented by one at step 5207.
After deciding the conformance/non-conformance of the
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new input cell, the processing returns to the idle state
at step 5202, at which a decision is made as to whether
the peak cell monitoring period TPCR is completed or not,
and proceeds to step 5208 when completed. The decision
of the completion is made even if the cell input does not
take place. At step S208, the CF>cR is placed to zero, the
TPCR is reset , and the Nsc~ is adjusted. The adjustment of
the NscR is carried out by sliding the sustainable traffic
monitoring period, and by subtracting from the NscR the
to number of cells excluded from the period by the sliding.
Subsequently, the processing returns to step 5202.
Fig. 10 is a diagram illustrating an example that
applies the traffic control processing of Fig. 9 to the
new cell transmitted. In Fig. 10, it is assumed that TPCR
- 4 [ cell times ] , TscR = 16 [ cell times ] ( n = 4 ) , XPCR = 2
[cells], and Xsca = 5 [cells]. When applying the control
processing to the cells transmitted, the CPCR and Nsc,~ vary
as shown in Fig. 10, and the cells at the seventh, 14th
and 18th cell times are decided as a non-conform cell
because Of XPCR < CF>cR + 1 , XscR < NscR + 1 arid XscR < Nsca +1 ,
respectively.
Although the control based on both the PCR and SCR is
carried out in the traffic control of the present
embodiment , the control based on one of them is possible .
Besides , a rate other than t=he PCR and SCR can be used as
the cell (traffic) rate.
Implementing appropriate control is possible by
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selecting, for the data generated in a burst mode at the
period proper to the data, t=he traffic monitoring period
with considering the proper period as in the present
embodiment.
Although the foregoing description of the present
invention is made by way of example of the ATM transmission,
the present invention is also applicable to other
transmission systems.
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