JP3444474B2 - ATM virtual path capacity setting method and ATM virtual path capacity setting apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to A in an Asynchronous Transfer Mode (ATM) network.
The present invention relates to a technique for obtaining the capacity of an ATM virtual path set between TM exchanges, and is particularly suitable for efficiently setting the ATM virtual path capacity that satisfies a predetermined cell loss rate target value (CLR). The present invention relates to an ATM virtual path capacity setting method and an ATM virtual path capacity setting device.

[0002]

2. Description of the Related Art A conventional circuit switched communication network such as a telephone service uses a synchronous transfer mode (STM).
ode). In this STM network, a line having a fixed band is set in a path set between two exchanges, and a line having various bands cannot be set. When individually operating communication networks that handle only fixed-bandwidth lines, it is not possible to flexibly support various communication services and new communication services, so efficient operation of network resources is limited. There is.

Packet communication is used in data communication networks such as packet communication services. In this packet communication network, data from an unspecified number of information sources is converted into packets of various lengths and transferred, but the data of the specified information source is converted to all other data flowing through the same transmission medium. Can have an impact. Therefore, the utilization efficiency of the transmission medium cannot be sufficiently increased while suppressing the data loss rate. Even if a communication network in which an unspecified large number is shared without limiting the bandwidth of such a transmission medium is operated, it is not possible to flexibly respond to various data characteristics and fluctuations in communication demand, and thus, like the above-mentioned technology, There are limits to the efficient operation of network resources.

In order to deal with such a problem, a broadband ISDN (Integrated Services Digi) that handles a plurality of communication services such as telephone, data communication and image communication in an integrated manner.
talNetwork), there is a technique using an asynchronous transfer mode (ATM). With this technique using ATM, all the communication information is converted into fixed length cells (ATM cells) and transferred, so that a unified exchange process independent of the type of communication service can be realized.

As a result, it is possible to logically set a usable band between two ATM exchanges as an ATM virtual path in place of the path in the above-mentioned technique. Further, it is also possible to logically set up a virtual circuit in which an unspecified number of information sources share the ATM virtual path under the limitation of the capacity of the ATM virtual path.

Information transfer using ATM cells is a technique similar to so-called time division multiplexing using time slots, but time slots for virtual circuits are not allocated in a time-periodic manner. Therefore, it is possible to dynamically allocate time slots according to a time-varying information transmission request, and various bands can be variably set by changing the number of transmission cells per unit time. .

That is, ATM is a transfer mode that enables unified transmission of all communication services from voice and data to images. A communication network that performs communication based on such ATM is called an ATM network. Regarding the structure of the transmission line network using the ATM virtual path, for example, "Structure method of high-speed burst multiplex transmission system" by Sato, Kaneda and Toisawa (Information and Communication Network Research Society of IEICE, IN87-84, 1987) and the like.

The functional configuration of a conventional ATM switch for setting the capacity of an ATM virtual path will be described below with reference to the drawings. FIG. 6 is a block diagram showing a configuration example of an ATM virtual path capacity setting mechanism in a conventional ATM exchange.

First, the physical functional configuration will be described. A
The cell transmission device 100a of the TM switch is provided with a cell transmission interface (described as "IF" in the figure) 101 for each physical transmission medium 200 of the transmission destination, and cell transmission exceeding the capacity of the transmission medium 200 is performed. Is designed to suppress. Also, when explaining the logical functional configuration,
ATM virtual paths (indicated as “virtual paths” in the figure) 201, 202, ...
・ Shaper (denoted as “S” in the figure) 111, 11 for each
2, ... are respectively connected.

The shapers 111, 112, ... Are ATMs.
It is intended to suppress cell transmission exceeding the logically determined capacity for the virtual paths 201, 202, .... Each cell transmission interface 101 and shaper 111,
Between 112, ..., Cells are transmitted at the timing according to a certain scheduling rule. Shaper and AT
The M virtual paths correspond to each other on a one-to-one basis. For example, the shapers 111 and 112 have ATM virtual paths 201 and 201, respectively.
It corresponds to 02, ...

Here, in order to make the explanation easy to understand, the capacity of each ATM virtual path is determined by the shapers 111 and 11.
It is assumed that the cell transmission rates of 2, ... Are the same. .. are connected to the shaper 111, 112, ..., And the cell output waiting buffers 121, 122 ,.
In (), when a cell exceeding the ATM virtual path capacity flows in, the cell is held up to the size of the cell transmission waiting buffers 121, 122, ... And waits for the next cell transmission timing.

Next, along with the flow of cells, cell transmission waiting buffers 121, 122, ...
The shapers 111, 112, ..., And the cell transmission interface 101 will be described. The cells switched according to the transmission medium 200 in the ATM exchange are routed to the cell transmission device 100. Logically, ATM
The cells are divided for each destination of the virtual paths 201, 202, ... And the cell streams 301, 302, ...
.. is added to the cell transmission device 100a.

For example, in the cell transmission waiting buffer 121 to which the cell stream 301 is added, the number of cells arriving during a preset period T is counted. Then, the cells arriving at the cell transmission waiting buffer 121 are processed in the order of arrival, and if the shaper 111 is in operation, the cells are accumulated in the cell transmission waiting buffer 121 and wait for the processing order to come. The number of cells waiting for transmission is called Q length.

The order of the cell processing in the cell transmission waiting buffer 121 comes in accordance with the scheduling rule defined in the shaper 111. When the processing order comes to the shaper 111, the cells accumulated in the cell transmission waiting buffer 121 pass through the shaper 111, proceed to the cell transmission interface 101, and are transmitted to the transmission medium 200.

Next, the conventional ATM virtual path capacity setting procedure in the above-mentioned ATM switch will be described as first to fourth conventional techniques. "First Conventional Technique" First, as a first conventional technique, a technique for modeling a cell arrival process by a Poisson process will be described.

This technique is characterized in that the ATM virtual path capacity can be easily determined by the only traffic measurement item, that is, the ATM virtual path usage rate. That is, in FIG. 6, the size of the cell transmission waiting buffer 121 is b,
When the cell loss rate target value is CLR, the ATM virtual path capacity C that satisfies the cell loss rate target value CLR for the cell flow 301 having the arrival rate λ to the ATM virtual path 201.
Is calculated by the following equation (Equation 1).

[Equation 1]

In this equation, M is a constant for converting the number of cells per unit time into a capacity, and the usage rate ρ is given by the following equation (Equation 2).

[Equation 2] The above equation (Equation 1) is derived on the basis of a point of concern. That is, it is known that the following equation (Equation 3) is established according to the principle of large deviation when the probability that the Q length distribution S is longer than the Q length k is P [S> k].

[Equation 3]

Further, especially when a cell arrives according to the Poisson process, the following equation (Equation 4) is established.

[Equation 4]

Applying the "Mo1ina formula" here,
The above equation (Equation 4) is expressed as the following approximate equation (Equation 5).

[Equation 5] Incidentally, such a technique is described in detail on pages 351 to 362 of "Communication Traffic Theory" by Fujiki and Karenbe.

In the above equation (Equation 5), the Q length k of the left side
Is equal to the buffer size b, the cell loss rate target value CLR is made to agree with the usage rate ρ at that time, and the following equation (Equation 6) is obtained.

[Equation 6] When this equation (Equation 6) is solved for the usage rate ρ, the above equation (Equation 2) is derived, and the ATM virtual path capacity C that provides the utilization rate ρ is derived by the above equation (Equation 1).

FIG. 7 shows a functional configuration of an ATM switch for realizing the first conventional technique, and the description thereof will be given. FIG. 7 shows an ATM for realizing the first conventional technique.
It is a block diagram showing an example of functional composition of an exchange. In the following description, the components already described in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted.

In the ATM exchange shown in the figure, the soft counters 131, 132, ...
.. are provided in association with 1, 122, ..., When the cells are logically distributed to the ATM virtual paths 201, 202 ,.

The setting device 400a collects the counting results of the software counters 131, 132, ... Input via the communication line 401a for each predetermined period T, and arrives at the arrival rate which is the number of arriving cells per unit time. λ is calculated by the following formula. λ = N / T

However, in such a first conventional technique, there is no guarantee that the modeling of the cell flow by the Poisson process is adequately valid. In other words, the burstiness of traffic is not so small that it can be modeled in the Poisson process. For reports on ATM traffic such as burstiness and large long-term correlation, see, for example, WE Leland, MSTaqq.
`` On the self '' by u, W.Willianger, and DV Wilson
-similer nature of Ethernet traffic (extended versi
on) '' IEEE / ACM Trans.Networking, vol.2, no.1, pp.1-15,
Detailed in 1994. Therefore, it is dangerous to set the capacity of the ATM virtual path of the ATM network in actual operation by the first conventional technique.

[Second Prior Art] Next, as a second prior art, a technique for collecting all the arrival times of cells and restoring the arrival process to obtain an ATM virtual path capacity which is sufficient will be described. FIG. 8 is a block diagram showing a functional configuration example of an ATM switch for realizing the second conventional technique. In this ATM switch, the cell transmission interface 1
01 and the external device 50 provided between the transmission medium 200
0, a flowing cell is copied (captured), or a part of the header is copied, and the copied data is sent to the storage device 510 via the communication line 501.

When the cell arrives, the storage device 510 stores the time stamp of the arrival time and the header of the cell. The header of this cell includes an identifier for identifying the ATM virtual path, and the storage device 510 classifies these time stamps for each ATM virtual path and shows the arrival process of the cell for each ATM virtual path. analyse. Examples of this analysis technique include a technique for creating a probability distribution of arrival processes, and a technique for obtaining the average and variance of arrival intervals and the third moment.

However, the storage device 510 capable of providing such a time stamp is expensive. The main cause is
Due to the technical difficulty of timestamping with sub-microsecond granularity needed to analyze the incoming cells. Further, since continuous capture can be performed (capture for several seconds every few minutes) only while the amount of memory installed in the storage device 510 permits, setting accuracy other than the capture interval cannot be guaranteed.

Depending on the specifications of the external device 500,
Some devices may not be able to capture only the header information added by the telecommunications provider, and the payload carrying the customer's telecommunications information may be sent to the outside, so the handling of the captured data must be done carefully. Furthermore, communication interruption when connecting the external device 500 between the cell transmission interface 101 and the transmission medium 200 is unavoidable. That is, in this technique, the communication of the customer is hindered due to the setting of the ATM virtual path capacity.

Since the cell flow that can be captured is the cell flow that has been arranged by the shapers 111, 112, ..., The burst property will be small, and the cell transmission waiting buffers 121, 122 ,. ･ ･ The cell that lost cell is not captured. This has a small effect in low-load operation, but has a large effect in accuracy reduction in setting the ATM virtual path capacity during high-load operation. Therefore, setting the ATM virtual path capacity of the ATM network in actual operation based on the second conventional technique is prohibitive and infeasible.

[Third Prior Art] Next, the third prior art will be described. Before that, the Q length distribution will be described with reference to FIG. FIG. 9 is an explanatory diagram showing an example of the Q length distribution. This Q-length distribution is created from traffic data measured by the same technique as the second conventional technique.

The Q-length distribution is the cell transmission waiting buffers 121, 122, ... Shown in FIG.
.. is the probability distribution of the number of cells (Q length) accumulated in, and one broken line in FIG. 9 indicates the Q length distribution based on the arrival time data of about 130,000 cell traffics. It was drawn. The horizontal axis is the number of cells in the buffer (Q length) k,
The vertical axis indicates the number of cells equal to or larger than the number of cells and the cell transmission waiting buffer 12
Probability P [S> accumulated in 1,122, ...
k] is expressed in logarithm.

In the range smaller than the reciprocal of the digit number of the measured cell number, the Q length distribution has no meaning. For example, if the traffic data captures 130,000 cells, 1
The probability of 0 ^-4 or less does not have enough meaning. In addition, in the attenuation factor of the Q-length distribution, the tail indicates that the Q-length k is relatively long.

It is generally known that in a stochastic process satisfying stationarity, rarity and independence, the occurrence probability of an event follows an exponential distribution (“Poisson's law of minority”).
This means that in the case of the system configuration of FIG. 7, the tail of the Q length distribution is approximated by a straight line. Here, the Q-length threshold value and the number of times it is exceeded will be described.

It is technically difficult to grasp all the distributions of the Q length, as described in the second prior art. Therefore, in order to partially understand the characteristics of the Q length, a mark (Q length threshold) is placed in the middle of the buffers arranged in a row, and the Q length is set to the Q length threshold each time a cell arrives. There is a technique of determining whether or not the value exceeds, and counting the result (the number of times the Q length threshold is exceeded). A value obtained by normalizing the number of times the Q length threshold is exceeded by the number of arriving cells is the Q length threshold excess frequency.

The third conventional technique is characterized in that two Q length thresholds are used in the above technique, and a Q length distribution is obtained by a straight line determined from two Q length threshold excess frequencies obtained from the Q length thresholds. Approximate the tail of damping. The solid line shown in FIG. 9 indicates that the Q length distribution is approximated by a straight line passing through the Q length thresholds at two points and the corresponding Q length threshold excess frequency.

A case where two Q length threshold values are set in each cell transmission waiting buffer 121, 122, ... Of the cell transmission apparatus 100 will be described below with reference to the functional block diagram of FIG. FIG. 10 is a block diagram showing an example of the functional configuration of an ATM switch when the Q length threshold is set to two points.

The cell transmission waiting buffers 121, 122, ...
Q length threshold 151A and second Q length threshold 151
B, the first Q length threshold value 152A and the second Q length threshold value 152B, ...
When 01 and 302 arrive, it is determined whether or not the Q length exceeds the first and second Q length thresholds. Of the judgment results, the result that the Q length exceeds the first Q length threshold value,
The result of exceeding the second Q length threshold value is counted every period T which is the same as the number of arriving cells. Then, this counting result is the number of times the first and second Q length thresholds are exceeded.

FIG. 11 shows a table in which only the data of the part relating to the ATM virtual path 201 among the counting results in the cell transmitting device 100b is summarized. Figure 11
FIG. 11 is an explanatory diagram showing an example of cell counting results by the cell transmission device in FIG. 10. Cell transmission device 100b of FIG.
The data counted in 1 is transmitted from the cell transmission device 100b to the virtual path capacity setting device 600 via the communication line 601, and is stored in the virtual path capacity setting device 600 as a table 1100 shown in FIG.

In this table 1100, 111
Reference numerals 0, 1120, 1130, and 1140 are records showing the columns of the counting cycle number, the number of arriving cells, the number of times the first Q-length threshold has been exceeded, and the number of times the second Q-length threshold has been exceeded.
11, 1112, ... Are records indicating counting cycle numbers, and 1121, 1122 ,.
The records of the number of arriving cells corresponding to 1, 1112, ...
The records of the first Q length threshold number of times corresponding to 1, 1112, ..., 1141, 1142, ... Are the second Q lengths corresponding to the counting cycle numbers 1111, 1112 ,. This is a record of the number of times the threshold is exceeded.

The virtual path capacity setting device 600 of FIG.
The data in the table 1100 shown in FIG.
The set capacity for the virtual path 201 is calculated. For the calculation, Shioda, Toyoizumi, Yokoi, Tsuchiya, Saito,
“Self-sizing network: a new network concept based o
n autonomous VP bandwidth adjustment, "Proc. of ITC
Using the calculation formula described in 15, pp.997-1006, 1997,
The procedure is as follows.

First, the record sequence 1120 of the number of arriving cells
Using {di}, the ATM in the cycle i is calculated by the following equation.
The virtual path usage rate {ρi} is calculated. ρi = M · di / C (i = 1, ..., N) where M is a constant for converting the number of cells per unit time into capacity, and C is the capacity set in the ATM virtual path 201.

Further, the following record sequence 1130 {q ₁ i} for the number of times the first Q length threshold has been exceeded and the second record sequence 1140 {q ₂ i} for the number of times the Q length threshold has been exceeded By the formula, the first threshold value excess frequency {p ₁ i} and the second threshold value excess frequency {p ₂ i} in the cycle i are calculated. p ₁ i = q ₁ i / di p ₂ i = q ₂ i / di

Further, the Q length distribution attenuation rate {δi} in the cycle i is calculated by the following equation. Where "s ₁ " is the first
Q length threshold 151A and “s ₂ ” is the second Q length threshold 151B. δi = (s ₂ −s ₁ ) / (logp ₁ i−logp ₂ i)

The intercept constant βi in the cycle i is calculated by the following equation. βi = Exp [(s ₂ logp ₁ −s ₁ logp ₂ ) / (s ₂ −s ₁ )] Next, the set capacity Ci in the cycle i is calculated by the following equation. Ci = (di / T) ( 1+ (m 2 i / (m 1 i-b)) logCLR)

"M ₁ i" and "m ₂ i" in this equation are as shown in the following equation, and T is the length of the counting period and b
Is the buffer size, and CLR is the cell loss rate target value. m ₁ i = δi · log βi m ₂ i = (ρi / (1-ρi)) (1 / δi)

Using the above calculation results, the set value Cd of the ATM virtual path capacity to be calculated is calculated by the following equation. Cd = Max {Ci | i = 1, ..., n) Cd = Cd (n), Cd (i + 1) = (1-α) Cd (i) + αCi,
i = 1, ..., N-1) Note that α is a constant of 0 ≦ α ≦ 1.

However, in such a third conventional technique,
It must be a special ATM switch that can set the Q length threshold. Further, the Q length threshold must be set by hardware. Therefore, changing the threshold value is very difficult. Moreover, it is not easy to properly select a plurality of Q length thresholds.

For example, if a relatively large value is set as the Q length threshold value, the Q length may not be extended to that point, and the Q length threshold excess frequency may not be collected. Further, if a relatively small value is set as the Q-length threshold value, the portion of the Q-length distribution that is sharply different from the tail is measured, and there is a possibility that an approximate straight line on the dangerous side is obtained. Further, the closer the two Q length thresholds are, the higher the accuracy of approximation of the straight line becomes, but
Due to the above-mentioned problems, it is difficult to find an appropriate interval.

"Fourth Prior Art" Next, the fourth prior art will be described. In the fourth conventional technique, the threshold (Q) is set for the number of cells (Q length) waiting in the cell transmission waiting buffer.
Long threshold) is used, and the number of times the Q length threshold is exceeded (Q length threshold exceeded) is counted,
Based on the number of cells arriving at the cell transmission waiting buffer and the number of times the Q length threshold is exceeded, the frequency of exceeding the Q length threshold (Q length threshold excess frequency) is calculated, and this Q length threshold is exceeded. This is a technique for estimating the Q length distribution attenuation rate using the frequency and the average and variance of the number of arriving cells, and estimating the ATM virtual path capacity that satisfies the cell loss target rate CLR. The calculation procedure used here is the same as the Japanese Patent Application No. 9-28584 by the inventors of the present application.
No. 5 ("ATM switch and ATM virtual path capacity setting method").

Hereinafter, with reference to the functional block diagram of FIG. 12, each cell transmission buffer 1 of the cell transmission device 100 (counting means)
21, 122, ...
A technique for setting the ATM virtual path capacity in the case where one point is set for each will be described. FIG. 12 is a block diagram showing a functional configuration example of an ATM switch for realizing the fourth conventional technique.

In FIG. 12, the number of arriving cells of each cell transmission waiting buffer 121, 122, ... Is counted by the soft counters 131, 132 ,. Whether or not the threshold value is exceeded,
It is determined by the cell transmission device 100c. Then, of the determination results, the result that the Q length exceeds the Q length threshold value is counted in every cycle T that is the same as the count of the number of arriving cells. It

Cell sending device 1 of such an ATM switch
The counting results of 00c are summarized in the table shown in FIG. FIG. 13 shows the ATM in FIG.
It is explanatory drawing which shows the structural example of the table which put together the counting result by the cell transmission apparatus of an exchange. This example is particularly shown in FIG.
Among the counting results of the cell transmitting device 100c, the data relating only to the ATM virtual path 201 is summarized in a table.

In the ATM exchange shown in FIG. 12, these data are sent to the cell sending device 100c via the communication line 601.
From the virtual path capacity setting device 600a.
The virtual path capacity setting device 6 as the table 1000 shown in FIG.
Stored in 00a.

In this table 1000, 1010
Is a counting cycle number (counting cycle number), 1020 is the number of arriving cells, 1030 is a record string indicating the number of times the Q length threshold is exceeded, 1011, 1012, ... Are records indicating the counting cycle number, 1021 , 1022, ... Are records of the number of arriving cells corresponding to the counting cycle numbers 1011, 1012, ..., 1031, 1032 ,. This is a record of the number of times the threshold is exceeded.

The virtual path setting device 600a of FIG. 12 processes the data of the table 1000 as follows, and
The set capacity for the M virtual path 201 is calculated. For simplicity of explanation, it is assumed that there is no missing data in the following explanation. Assuming that the measurement result in the counting cycle T (for example, 20 seconds) is obtained within the predetermined time (for example, 1 hour), the total number of times of counting n in this case is 180.

Record sequence 1020 {di} of the number of arriving cells
Using, the average arrival rate λ during the measurement period is calculated by the following equation. In this equation, n is the data size and T is the counting cycle. λ = Σdi / (nT), (i = 1, ..., n)

Further, the dispersion ratio V of the number of arriving cells during the measurement period is calculated based on the following equation. V = Σ (di−λ) ² / (nT), (i = 1, ..., N) Furthermore, the record 1030 of the number of times the Q length threshold is exceeded.
Based on {qi}, the Q length threshold excess frequency p during the measurement period is calculated by the following equation. p = Σqi / Σdi, (i = 1, ..., n)

Then, using the above calculation results, the Q length distribution attenuation rate δ is estimated based on the following equation. Incidentally, C is the capacity of the current ATM virtual path. δ = 2 (C−λ) / V Further, the intercept constant β is estimated by the following equation. Note that b is the buffer size. β = ρExp [2b (C-1) / V]

Based on these calculation results, the tail of the attenuation factor of the Q-length distribution is approximated, and the set value Cd of the ATM virtual path capacity to be calculated is calculated by the following equation. In addition, M is a constant for converting the number of cells into capacity, and CLR is a cell loss rate target value. Cd = M (1 + Vlog [b / CLR] / (2b))

However, in such a fourth conventional technique,
As with the third prior art, it must be a special ATM switch that can set the Q length threshold. Also, the Q length threshold must be set by hardware.
Therefore, changing the threshold value is very difficult. Moreover, it is not easy to properly select the Q length threshold value.

As a result, in addition to having the same problem as the above-mentioned third conventional technique, and further, since the Q length threshold value is one point, the estimated value of the attenuation rate is small for a slight fluctuation of the data. There is a possibility of large fluctuations, and the reliability of the estimated value of the attenuation rate becomes lower than that of the third conventional technique.

The characteristics of the above-mentioned conventional technology relating to the setting of the ATM virtual path capacity are summarized as follows. In the first conventional technique, the ATM switch can determine the parameters of the ATM virtual path capacity calculation formula with a simple traffic measurement item. There is a problem that the long-term correlation cannot be considered.

In the second conventional technique, it is possible to accurately calculate the ATM virtual path capacity by capturing the cell traffic data by the external device, but it requires an expensive external device, and it is complicated to request the customer to disconnect the communication. There is a problem that the traffic must be captured and the data analyzed by operating an external device, and the analysis result can be applied only for a short time when the capture is possible.

In the third prior art, it is possible to obtain a straight line that relatively accurately approximates the tail of the attenuation rate of the Q-length distribution from the two Q-length threshold excess frequencies, and the ATM based on this can be obtained.
The virtual path capacity can be calculated. However, this technique can be realized only by a special ATM switch capable of setting the Q length threshold. Further, since it is difficult to select the Q length threshold value and the Q length threshold value is set by hardware, it is very difficult to change the Q length threshold value if it is inappropriate. There is a problem.

According to the fourth conventional technique, the ATM virtual path capacity can be calculated with less data than the third conventional technique. However, like the third prior art, it can be realized only by a special ATM exchange in which the Q length threshold can be set. Also, it is difficult to select the Q length threshold, and the Q
Since the long threshold value is set by hardware, there is a problem that it is very difficult to change the Q length threshold value when the setting is inappropriate. In addition, since the Q length threshold is 1 point, there is a possibility that the estimated value of the attenuation rate may fluctuate greatly with a slight fluctuation of the data, and the reliability of the estimated value of the attenuation rate becomes low. There is.

[0066]

The problem to be solved is that the prior art cannot efficiently set up an ATM virtual path that satisfies a predetermined cell loss rate target value (CLR). Is. An object of the present invention is to solve the above problems of the prior art and to enable an efficient operation of ATM network resources, and an ATM virtual path capacity setting method and an ATM virtual path capacity setting method.
It is to provide a TM virtual path capacity setting device.

[0067]

To achieve the above object, an ATM virtual path capacity setting method and an ATM according to the present invention are provided.
The virtual path capacity setting device measures the number of cells arriving at the cell transmission waiting buffer that accompanies the ATM virtual path, and this number of arriving cells is a threshold for the number of cells arriving in a unit time (arrival cell number threshold). Value) and the number of times that the product of the preset constant period T is exceeded (first number of times of arrival cell number threshold exceedance) is measured for each past data use period T ′, and the number of arrival cells threshold is set. The excess frequency (first arrival cell count threshold excess frequency) is calculated, and the measured arrival cell count exceeds the product of the arrival cell count threshold and an integer k times (kT) of the period T. The number of times (the number of times the second arriving cell number threshold is exceeded) is measured for each cycle T ', and the frequency of exceeding the number of arriving cells threshold (the frequency of exceeding the second arriving cell number threshold) is calculated. To do. Then, the attenuation rate of the complementary distribution of the number of cells arriving per unit time is obtained from the first and second arrival cell number threshold excess frequencies, and the period T is calculated based on the number of arriving cells counted for each period T. The average of the number of arriving cells (average cell rate) and the variance are obtained, and the arrival process of the cells is regarded as an ON-OFF process from the average and the variance and the attenuation rate of the complementary distribution of the number of cells arriving per unit time. The peak cell rate and the transition probabilities a and d from ON to OFF and from OFF to ON for each time (time slot) that is the reciprocal of the peak cell rate are obtained, and these peak cell rate and transition probabilities a and d are obtained. To satisfy the cell loss target rate A
Calculate the TM virtual path capacity.

[0068]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a flow chart showing an example of processing operation of the ATM virtual path capacity setting method of the present invention, and FIG. 2 is a configuration of the ATM virtual path capacity setting apparatus of the present invention and an ATM switch having the same according to the present invention. It is a block diagram which shows one Example.

The ATM exchange shown in FIG. 2 has a cell transmission device 100, like the ATM exchanges shown in FIGS. 6 to 8, 10 and 12 in the prior art, and the cell transmission device 100 has a transmission destination. Cell transmission interface (described as “IF” in the figure) 101 for each physical transmission medium 200
Is provided to suppress cell transmission exceeding the capacity of the transmission medium 200.

As a logical functional configuration, the cell transmission interface 101 has an ATM virtual path 201,
Shaper for each 202, ... (Indicated as “S” in the figure) 1
11, 112, ... Are connected to each other. The shapers 111, 112, ... Are for suppressing the cell transmission exceeding the capacity logically determined for the ATM virtual path, and are in timing with the cell transmission interface 101 according to a certain scheduling rule. The cell is transmitted with. In addition, each shaper 111, 112, ...
.. are ATM virtual paths 201, 202, ...
・ There is a one-to-one correspondence with.

Further, each shaper 111, 112, ...
Are connected to cell transmission waiting buffers 121, 122, ...
, 122, ..., When cells exceeding the ATM virtual path capacity are rushed, cell transmission waiting buffers 121, 12
Holds cells up to the size of 2, ... And waits for the next cell transmission timing.

Further, each cell transmission waiting buffer 121, 12
2, ... are soft counters 131, 132, ...
・ The soft counters 131 and 13 are additionally provided.
2, ..., logically ATM virtual paths 201,
When the cell streams 301 and 302 are distributed to 02, ..., The number of arriving cells for each ATM virtual path is counted. The count results of the soft counters 131, 132, ... Are sent to the ATM virtual path capacity setting device 400 via the signal line 401.

ATM virtual path capacity setting device 400 of this example
Is a cell number counting unit 1, a table 2, a threshold value registering unit 3,
It has an excess number counting unit 4, a table 5, a frequency calculation unit 6, and a set capacity calculation unit 7, and software counters 131, 132, ...
.. AT that terminates at the ATM switch based on the counting result of
ATM that satisfies the cell loss target rate for M virtual paths
Set the virtual path capacity.

That is, the soft counters 131 and 13
Based on the counting result of 2, ..., the cell number counting unit 1 causes the cell transmission waiting buffer 12 for each preset cycle T
The number of cells arriving at 1, 122, ... Is counted and registered in the table 2, and based on the registered contents of the table 2, the excess frequency counting unit 4 presets it in the threshold value registration unit 3. The number of times (excess number) that exceeds the product of the number of arriving cells per unit time (threshold number of arriving cells) and the period T is counted for each period, and the counting result is registered in the table 5. Based on the registered contents of the table 5, the frequency calculation unit 6
Then, the frequency of the number of excesses is calculated.

Then, the set capacity calculation unit 7 performs the process described in detail below based on the frequency calculated by the frequency calculation unit 6 and the number of arriving cells calculated by the cell number counting unit 1, and the cell transmission waiting buffer The cell loss in 121, 122, ... Is efficiently obtained, and the set capacity of the ATM virtual path satisfying the predetermined cell loss rate target value is obtained at high speed and with high accuracy.

FIG. 3 is an explanatory diagram showing a configuration example of a table for registering the counting result of the cell number counting section in FIG.
FIG. 4 is an explanatory diagram showing a configuration example of a table in which the counting result of the excess number counting unit in FIG. 2 is registered. Table 2 shown in FIG. 3 is a table in which only the data of the portion relating to the ATM virtual path 201 in the counting result of the cell transmitting device 100 of the ATM exchange shown in FIG.

In Table 2, reference numerals 21 and 22 are records showing the numbers of counting cycles (counting cycle numbers) and columns of the number of arriving cells, and 211, 212, ... Are records showing the numbers of counting cycles. 221, 222, ... Are records of the number of arriving cells corresponding to the counting cycle numbers 211, 212 ,. Here, the counting cycle number 211 indicates the immediately preceding counting cycle, and the counting cycle number 212 indicates the counting cycle immediately before the counting cycle number 211.

In the table 5 shown in FIG. 4, 51,5
Similar to 21 and 22 in Table 2 of FIG. 3, 2 is a record showing the number of the counting cycle (counting cycle number) and the column of the number of arriving cells, and 53 is the threshold of the number of arriving cells at each cycle number. Is a record of the number of times (number of arrival thresholds exceeded), 54 is a record of the number of arriving cells in a unit of a cycle kT that is k (an integer) times the cycle T, and 55 is a cycle k.
This is a record of the number of arrival thresholds exceeded in T units.

In the ATM virtual path capacity setting device 400 shown in FIG. 2, the excess count counter 4 processes the data in the table 2 as follows to create the table 5, and the frequency calculator 6 and the set capacity calculator The unit 7 calculates the set capacity for the ATM virtual path 201. For simplicity of explanation, it is assumed that there is no missing data in the following explanation.

Predetermined past data use cycle T '
A predetermined counting cycle T (for example, 20 hours)
If the measurement result in (sec) is obtained, the total number of counts n in this case is 180.

The excess number counting unit 4 records the arrival cell number in the table 2 in the table 2 by the product of the arrival cell number threshold value registered in advance in the threshold value registration unit 3 and the measurement period T.
{Di} (i = 1, ..., N) is compared to determine whether the number of arriving cells exceeds the threshold, and the number of excesses is recorded in the record string 53 {qi} in the table 5 of FIG. register. Here, qi takes 1 or 0. Based on the registered contents of the table 5, the frequency calculation unit 6 of FIG. 2 calculates the arrival cell number threshold excess frequency P of the cycle T based on the following formula. P = Σqi / (T '/ T), (i = 1, ..., T' / T)

Further, the excess number counting unit 4 obtains the number of arriving cells {dki} in the period kT which is an integer k times the counting period T based on the following equation, and records the number of arriving cells in the table 5 in FIG. 54. dki = Σdj, (j = i, ..., i + k-1) Furthermore, the excess number counting unit 4 calculates the product of the threshold value of the number of arriving cells and the period kT and the record string {dki of the number of arriving cells {dki. }, The number of times the number of arriving cells in the cycle kT exceeds the threshold value {qki} is obtained, and is registered in the record column 55 of the number of times the arrival threshold value is exceeded in the table 5 of FIG.

Based on the registered contents of this table 5, FIG.
The frequency calculation unit 6 calculates the arrival cell number threshold excess frequency Pk of the cycle kT based on the following equation. Pk = Σqki / (T '/ (T-k + 1)), (i = 1, ..., T' / (Tk
+1)) P and Pk are calculated for each counting cycle, P is calculated from the past n cycles of data, and Pk is calculated from the past (n−k + 1) cycles of data.

The average cell rate λ in the past data use cycle T'is calculated by the following equation. λ = Σdi / (T ′ / T), (i = 1, ..., T ′ / T) Further, the variance V of the number of arriving cells is calculated by the following equation. V = Σ (di−λ) ² / (T ′ / T), (i = 1, ..., T ′ / T)

Next, the approximation to the ON-OFF process will be described. Now, let Ψ be the peak cell rate of the past data use period T ′ in the ON-OFF process. When the reciprocal of this peak cell rate is called a time slot, the transition probability from the OFF state to the ON state between the time slots is a, and the transition probability from the ON state to the OFF state is d. Here, the ON state means a state in which a cell exists in the time slot, and the OFF state means a state in which no cell exists in the time slot.

The transition probabilities a and d and the peak cell rate Ψ are expressed in the above equations (Equations 7 to 10) as described above.
Threshold value of the number of arriving cells in the periods T and Tk thus obtained
Excess frequency P, Pk, average cell rate λ and number of arriving cells
More is required to be solved by substituting the variance V and the like.

[Equation 7]

[Equation 8]

[Equation 9]

In this equation (Equation 9) , the left side is the unit time
Of the probability that the number of cells arriving in the interval will exceed the threshold
Decay rate, that is, the number of cells arriving per unit time
The attenuation value (ζ) of the complementary distribution is measured (arrival of period T, kT
The number of cells exceeds the threshold frequency P, Pk)
Yes, and the right side arrives at this "per unit time
A large deviation source corresponding to the damping ratio (ζ) of the complementary distribution of the number of cells
It is a formula that is established by theory, γ is the threshold value of the number of arriving cells, and μ (θ) satisfies the following formula (Formula 10).

[Equation 10] Note that the calculation formula of the formulas (Numerical Expressions 9 and 10) is “Exponential bounds for queues with Markovian arri” by NGDuffield.
vals ", Queueing Systems 17, pp.413-430 (1994).

The target cell loss rate CLR is approximated by the following equation (Equation 11) under the approximation of the ON-OFF process.

[Equation 11] Here, x satisfies the following equation (Equation 12).

[Equation 12]

Y which satisfies these equations (Equations 11 and 12) is obtained, and the cell loss target rate CL is calculated from the following equation (Equation 13).
An ATM virtual path capacity Cd that satisfies R is calculated.

[Equation 13] Here, M is a constant for converting the number of cells per unit time into a capacity.

The estimated cell loss rate CLRe is x, with respect to a, d and Ψ calculated from the above equations (Equations 7 to 9).
y is calculated from the following equations (Equations 14 and 15), and
It is calculated by substituting it on the right side of 1).

[Equation 14]

[Equation 15] Note that γ ′ × M is the current ATM virtual path capacity.

FIG. 1 shows an example of the processing operation of such an ATM virtual path capacity setting device. First, the number of arriving cells (di) for each predetermined period T in the period T'to be measured is counted. Then, (step S1), based on the number of arriving cells (di), the number of times the threshold is exceeded (qi,
qki) is obtained (step S2). Then, using these threshold value excess times (qi, qki), the threshold value excess frequency (P, Pk) in the cycle T and the cycle kT is obtained (step S3).

The logarithm of the frequency over threshold (P, Pk) in the period T and the period kT is obtained (step S
4) Based on this, the attenuation rate (ζ) of the complementary distribution of the number of arriving cells per unit time is obtained from the left side of Equation 9 (step S5). In addition, the number of arriving cells (d
i) is used to calculate the average cell rate (λ) (step S6), and this average cell rate (λ) and the number of arriving cells (d
Based on i), the variance (V) of the number of arriving cells is obtained (step S7).

Then, the cell arrival process is turned on by solving the equations ( 7 ) to ( 10 ) based on the attenuation rate (ζ), the arrival cell number variance (V) and the average cell rate (λ) thus obtained. -A peak cell rate (Ψ) when regarded as an OFF process, and ON to OFF and OFF to O for each time (time slot) that is the reciprocal of this peak cell rate.
The transition probability (a, d) of transition to N is obtained (step S
8).

Then, the transition probabilities (a, d) are substituted into a preset approximation formula of the cell loss target rate CLR, and another variable (y) constituting this approximation formula is obtained (step S
9), based on the calculated variable (y), transition probability (a, d) and peak cell rate (Ψ), ATM virtual path capacity C
d is calculated (step S10).

FIG. 5 is an explanatory diagram showing an example of the processing result by the ATM virtual path capacity setting device in FIG. ATM
The virtual path is a multiplexing of a plurality of ATM virtual circuits. Assuming that cells arrive according to the ON-OFF process of each ATM virtual circuit, in this example, A
ON / OFF in the TM virtual path without considering multiplexing
The cells are supposed to arrive according to the process.

The Q length distribution for a multiplexed cell stream arriving according to the same ON-OFF process is "DDBo
tvich and NGDuffield: "Large deviations, the sh
apeof the loss curve, and economies of scale in la
rge multiplexers ", Queueing System 20 (1995) pp.29
3-320 ”. FIG. 5 shows a case in which cell streams arriving according to the same ON-OFF process are multiplexed,
It is a comparison of the virtual path capacity calculation result considering multiplexing and the calculation result of this example.

Particularly, in the example of FIG. 5, the peak rate is 10
Mbps, 10 ATM virtual circuits according to ON-OFF process with burst duration of 10 msec are multiplexed, and 60 Mbps V
When accommodated in P (virtual path), the target cell loss rate is 10 ^-6
Shows the result of comparison between the calculated value of the ATM virtual path capacity according to the present invention and the calculated value of the ATM virtual path capacity in consideration of multiplexing, which is calculated by the ATM virtual path capacity setting device of this example. It is shown that the ATM virtual path capacity is calculated on the safe side (larger capacity) as compared with the one considering the multiplexing.

As described above with reference to FIGS. 1 to 5, the ATM virtual path capacity setting method and AT of this embodiment are described.
The M virtual path capacity setting device counts the number of cells arriving at the cell transmission waiting buffer associated with the ATM virtual path, and the number of arriving cells is the threshold value of the number of arriving cells per unit time (the number of arriving cells threshold). Value) and preset measurement time T,
By calculating the frequency that exceeds the product of kT and AT
An ATM that efficiently obtains the cell loss in the cell transmission waiting buffer associated with the M virtual path and that conforms to the actual traffic demand
The virtual path capacity can be set, and the capacity can be set at high speed and with high accuracy based on actual traffic measurement and in line with actual traffic demand.

That is, in this embodiment, the Q-length complementary distribution function can be estimated at high speed by the extremely lightweight traffic measurement of the number of cells arriving at the cell transmission waiting buffer, and the arrival process can be approximated by the ON-OFF process. Therefore, bursty traffic is also considered. Further, since the threshold value of the number of arriving cells is set by software, it is easy to change the threshold value, and the frequency of exceeding the threshold value of the number of arriving cells can be calculated with high accuracy.

In order to find the tail of the distribution function of the number of cells arriving in a unit time, within a predetermined measurement period T,
The number of times the number of arriving cells exceeds the product of the threshold number of arriving cells and T, and the number of times the number of arriving cells exceeds the product of the threshold number of arriving cells and kT within a time that is an integer k times T Since the inclination of the straight line (attenuation rate) is obtained using the two pieces of information described above, highly accurate estimation is possible. As a result, the arrival cell number distribution function can be estimated with high accuracy, and the Q-length complementary distribution function can be estimated with high accuracy.

Further, the calculated value of the ATM virtual path capacity by the ATM virtual path capacity setting method and the ATM virtual path capacity setting device of this example is on the safe side (large capacity) as compared with the technique considering the multiplexing. is there. With these, in particular,
UBR (Unspecified Bit Rate) Capacity of ATM virtual path that accommodates best-effort virtual circuits such as bearer class is set to a certain cell loss rate target value (not a specified value)
It is possible to design (set) to satisfy.

Furthermore, it is possible to check and record day by day that the resources of the ATM network are properly arranged in the ATM virtual path and are effectively used, and the traffic flows evenly throughout the network. Confirmation is possible. In addition, it is possible to provide information for appropriate reconfiguration in a reasonable operation and period for changes in the network configuration such as new subscription and relocation of virtual circuits.

The present invention is not limited to the embodiment described with reference to FIGS. 1 to 5, but various modifications can be made without departing from the scope of the invention. For example, in the present example, the portion for performing the processing according to the present invention is divided into the cell counting unit 1, the excess number counting unit 4, the frequency calculating unit 6, and the set capacity calculating unit 7, respectively. The integration and division of functions may be performed in arbitrary module units according to the actual design.

[0104]

According to the present invention, an AT having a special function
The ATM of the ATM network in actual operation is used by using the data obtained by the simple traffic measurement in the ATM switch without using a special measurement form such as the M switch or the external device.
The virtual path capacity is set to a predetermined cell loss rate target value (C
LR) can be set so that network resources can be efficiently operated.

[Brief description of drawings]

FIG. 1 is a flowchart showing an example of processing operation of an ATM virtual path capacity setting method of the present invention.

FIG. 2 is a block diagram showing an embodiment of a configuration according to the present invention of an ATM virtual path capacity setting device of the present invention and an ATM exchange provided with the same.

FIG. 3 is an explanatory diagram showing a configuration example of a table for registering a counting result of a cell number counting unit in FIG.

FIG. 4 is an explanatory diagram showing a configuration example of a table for registering the counting result of the excess number counting unit in FIG.

5 is an explanatory diagram showing an example of a processing result by the ATM virtual path capacity setting device in FIG.

FIG. 6 is a block diagram showing a configuration example of an ATM virtual path capacity setting mechanism in a conventional ATM switch.

FIG. 7 is a block diagram showing a functional configuration example of an ATM switch for realizing the first conventional technique.

FIG. 8 is a block diagram showing an example of the functional configuration of an ATM exchange for realizing the second conventional technique.

FIG. 9 is an explanatory diagram showing an example of Q length distribution.

FIG. 10 is an ATM when two Q length thresholds are set.
It is a block diagram showing an example of functional composition of an exchange.

11 is an explanatory diagram showing an example of cell counting results by the cell transmission device in FIG.

FIG. 12 is a block diagram showing a functional configuration example of an ATM switch for realizing a fourth conventional technique.

13 is an explanatory diagram showing a configuration example of a table in which the counting results by the cell transmitting device of the ATM exchange shown in FIG. 12 are summarized.

[Explanation of symbols]

1: cell number counting unit, 2: table, 3: threshold value registering unit, 4: excess number counting unit, 5: table, 6: frequency calculating unit, 7: set capacity calculating unit, 21: record string (counting cycle) ), 22: record string (number of arriving cells), 211, 21
2: record (counting cycle), 221, 222: record (number of arriving cells), 51: record string (counting cycle), 5
2: record string (number of arriving cells), 511, 512: record (counting period), 521, 522: record (number of arriving cells), 53: record string (number of arrival thresholds exceeded),
531, 532: record (number of arrival thresholds exceeded),
54: record sequence (number of arrival cells), 541, 542: record (number of arrival cells), 55: record sequence (number of arrival thresholds exceeded), 551, 552: record (number of arrival thresholds exceeded), 100, 100a, 100b, 100
c: cell transmission device, 101: cell transmission interface,
111, 112: shaper, 121, 122: cell transmission waiting buffer, 131, 132: soft counter, 20
0: Transmission medium, 201, 202: ATM virtual path, 30
1, 302: cell flow, 400: ATM virtual path capacity setting device, 400a: setting device, 600, 600a: virtual path capacity setting device, 401, 401a, 501, 601:
Communication line, 500: external device, 510: storage device, 100
0,1001,1100: table, 1010,111
0: record string (counting cycle), 1011, 1012, 1
111, 1112: record (counting period), 1020,
1120: Record string (number of arriving cells), 1021, 10
22, 1121, 1122: record (number of arriving cells),
1030: record string (number of times Q threshold exceeds), 10
31, 1032: record (number of times Q length threshold exceeded),
1040: Record string (Q length threshold excess frequency), 10
41, 1042: record (Q length threshold excess frequency),
1050: record string (judgment result), 1051, 105
2: Record (judgment result), 1130: Record string (first Q length threshold exceeded count), 1131, 1132: Record (first Q length threshold exceeded count), 1140: Record string (second count) Q length threshold exceeded number), 1141,
1142: Record (number of times the second Q length threshold is exceeded).

Continuation of the front page (56) References JP-A-11-122267 (JP, A) JP-A-11-154952 (JP, A) Daisuke Sato et al. Optimum of distributed control in VP capacity control, 1998 Electronic Information and Communication Society Society Conference, Japan, The Institute of Electronics, Information and Communication Engineers, 1998, B-7-68, p189 Daisuke Sato et al. Convergence of VP capacity control algorithm to optimal solution, 1997 IEICE General Conference Conference, Japan, The Institute of Electronics, Information and Communication Engineers, 1997, B-7-194, p323 Shigeo SHIODA et al. , Real-time Cell Loss Ratio Estimation and Its Application to ATM Traffic Controls, Proceedings Vol. 3 IEEE INFOCOM'97, USA, IEEE, April 7, 1997, 9a. 3.1-8, pp1072-1079 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/28 H04Q 3/00

Claims (6)

(57) [Claims] 1. A capacity of an ATM virtual path set between ATM exchanges in an asynchronous transfer mode network (ATM network),
In an ATM virtual path capacity setting method of an ATM virtual path capacity setting device for calculating so as to satisfy a cell loss target rate, the number of cells arriving in a unit time in a cell transmission waiting buffer associated with the ATM virtual path is preset. The first step of registering the threshold value (the threshold value of the number of arriving cells), and the second step of counting the number of arriving cells to the cell transmission buffer for each preset period T; The number of times that the counted number of arrival cells exceeds the product of the threshold value of arrival cells and the period T is counted for each past data utilization period T ′, and the frequency of exceeding the threshold number of arrival cells (first Third frequency for calculating the number of arriving cells threshold exceeding frequency)
And the number of times the counted number of arriving cells exceeds the product of the threshold value of the number of arriving cells and an integer k times (kT) of the period T for each period T ′. A fourth step of calculating a frequency at which the number threshold is exceeded (second arrival cell number threshold excess frequency), the first arrival cell number threshold excess frequency and the second arrival cell number A fifth step of obtaining an attenuation rate of a complementary distribution of the number of cells arriving per unit time based on a threshold excess frequency, and the first and second arrival cell number threshold excess frequencies A that satisfies the cell loss target rate is obtained by using the attenuation rate of the complementary distribution of the number of cells arriving per unit time obtained based on
An ATM virtual path capacity setting method characterized by obtaining a TM virtual path capacity. 2. The ATM virtual path capacity setting method according to claim 1, wherein an average (average cell rate) of the number of arriving cells in the period T ′ is calculated based on the number of arriving cells counted in each period T. And the average cell rate and the number of arriving cells counted for each period T,
The seventh step of obtaining the variance of the number of arriving cells in the period T ′, the attenuation rate of the complementary distribution obtained in the fifth step, the average cell rate obtained in the sixth and seventh steps, and the arrival Based on the variance of the number of cells, the peak cell rate when the cell arrival process is regarded as an ON-OFF process, and transitions from ON to OFF and from OFF to ON at every time (time slot) that is the reciprocal of the peak cell rate. Eighth step of obtaining probabilities a and d, and using the peak cell rate and the transition probabilities a and d, an ATM virtual path capacity that satisfies the cell loss target rate is obtained. ATM virtual path capacity setting method. 3. The capacity of an ATM virtual path set between ATM switches in an asynchronous transfer mode network (ATM network),
In an ATM virtual path capacity setting method of an ATM virtual path capacity setting device for calculating so as to satisfy a cell loss target rate, the number of cells arriving in a unit time in a cell transmission waiting buffer associated with the ATM virtual path is preset. The registered threshold value (the threshold value of the number of arriving cells), the step of counting the number of arriving cells to the cell sending buffer for each preset period T, and the counted number of arriving cells is , The number of times the product of the threshold value of the number of arriving cells and the period T is exceeded (the number of times the first threshold value of the number of arriving cells is exceeded)
Is counted for each past data usage period T ′,
Calculating a frequency (first arrival cell number threshold excess frequency) of exceeding the arrival cell number threshold value based on the first number of arrival cell number threshold values, and the counted arrival cells The number of times the number exceeds the product of the threshold value of the number of arriving cells and the integer k times (kT) of the period T (the number of times the second threshold value of arriving cells is exceeded) is counted for each period T ′. And a frequency of exceeding the number of arriving cells threshold based on the number of times the second number of arriving cells threshold is exceeded (second
The number of arriving cells exceeding the threshold value), and the average number of arriving cells in the period T ′ (average cell rate) based on the number of arriving cells counted in each period T.
Determining the average cell rate and the period T
Determining the variance of the number of arriving cells in the period T ′ based on the number of arriving cells counted for each, and the third arriving cell threshold that is the logarithm of the first arriving cell number threshold excess frequency. Calculating a frequency excess frequency, and the second step
Calculating a fourth arriving cell count threshold excess frequency, which is a logarithm of the arriving cell count threshold excess frequency, and, based on the third and fourth arriving cell count threshold excess frequencies, The step of obtaining the attenuation rate of the complementary distribution of the number of cells arriving per unit time, and the cell arrival process is regarded as an ON-OFF process based on the attenuation rate of the complementary distribution, the average cell rate, and the variance of the number of arriving cells. The peak cell rate and the probabilities a and d of transition from ON to OFF and from OFF to ON for each time (time slot) that is the reciprocal of the peak cell rate, and the peak cell rate and the probability of transition. an ATM virtual path capacity satisfying the cell loss target rate based on a and d and the cell loss target rate. How to set. 4. The capacity of an ATM virtual path set between ATM exchanges in an asynchronous transfer mode network (ATM network),
In an ATM virtual path capacity setting device that calculates to satisfy a cell loss target rate, a preset threshold value for the number of cells arriving in a unit time to a cell transmission waiting buffer associated with the ATM virtual path (arrival Cell number threshold value), means for counting the number of cells arriving at the cell transmission buffer for each preset period T,
The number of times the counted number of arriving cells exceeds the product of the threshold number of arriving cells and the period T (number of times the first arriving cell number threshold is exceeded), the arriving cell number threshold and the Means for counting, for each cycle T ′, the number of times that the product of the cycle T and an integer k times (kT) is exceeded (the number of times the second threshold number of arriving cells is exceeded); and the first number of arriving cells. The frequency of exceeding the number of arriving cells threshold (first arriving cell number threshold excess frequency) is calculated based on the number of times the threshold is exceeded, and the second number is calculated.
Means for calculating the frequency of exceeding the arrival cell number threshold value (second arrival cell number threshold excess frequency) on the basis of the number of arrival cell number threshold excesses of the first arrival cell number Based on the threshold frequency excess frequency and the second arrival cell number threshold excess frequency, the attenuation rate of the complementary distribution of the number of cells arriving per unit time is obtained, and the obtained attenuation rate of the complementary distribution is used, Means for determining an ATM virtual path capacity that satisfies the cell loss target rate, and an ATM virtual path capacity setting device. 5. The ATM virtual path capacity setting device according to claim 4, wherein the ATM satisfies the cell loss target rate.
Means for obtaining the virtual path capacity are means for obtaining an average (average cell rate) of the number of arriving cells in the period T'based on the number of arriving cells counted for each period T, and counting the average cell rate and each period T. Means for obtaining the variance of the number of arriving cells in the period T ′ based on the number of arriving cells, and turning on the cell arrival process based on the attenuation rate of the complementary distribution, the average cell rate, and the variance of the arriving cells.
-The peak cell rate when it is regarded as an OFF process and O at every reciprocal time (time slot) of the peak cell rate
Probability a of transition from N to OFF and from OFF to ON,
A means for obtaining d, and using the peak cell rate and the transition probabilities a and d, obtains an ATM virtual path capacity that satisfies the cell loss target rate.
TM virtual path capacity setting device. 6. The capacity of an ATM virtual path set between ATM switches in an asynchronous transfer mode network (ATM network),
In an ATM virtual path capacity setting device that calculates to satisfy a cell loss target rate, a preset threshold value for the number of cells arriving in a unit time to a cell transmission waiting buffer associated with the ATM virtual path (arrival Cell number threshold value), means for counting the number of cells arriving at the cell transmission buffer for each preset period T,
The number of times the number of arriving cells counted by the means exceeds the product of the threshold value of the number of arriving cells and the period T (the number of times the first threshold value of arriving cells is exceeded) and the number of arriving cells threshold value Means for counting, for each cycle T ′, the number of times that the product of the cycle T and an integer k times (kT) has been exceeded (the number of times the second arrival cell number threshold has been exceeded); and the first arrival cell. The frequency (first arrival cell count threshold excess frequency) of exceeding the arrival cell count threshold is calculated based on the number threshold crossing count, and is calculated as the second arrival cell count threshold excess count. Means for calculating the frequency of exceeding the number of arriving cells threshold (second arriving cell number threshold excess frequency) based on the
The average of the number of arriving cells in the period T '(average cell rate) is obtained based on the number of arriving cells counted for each period, and the arrival in the period T'is based on the average cell rate and the number of arriving cells counted in each period T. The variance of the number of cells is calculated, the logarithm of the frequency of exceeding the first threshold number of arriving cells per unit time is taken to calculate the frequency of exceeding the third threshold number of arriving cells, and the third frequency per unit time is calculated. A logarithm of the frequency of exceeding the threshold number of arriving cells of 2 is calculated to calculate the frequency of exceeding the threshold number of arriving cells, and the unit time is calculated based on the frequency of exceeding the threshold number of arriving cells of 3rd and 4th. Determine the attenuation rate of the complementary distribution of the number of cells arriving per hit, based on the attenuation rate of the complementary distribution and the average cell rate and the variance of the number of arriving cells,
The peak cell rate when the cell arrival process is regarded as an ON-OFF process, and ON to OFF and OFF to O for each time (time slot) that is the reciprocal of the peak cell rate.
Means for obtaining the probabilities a and d of transition to N, and an ATM virtual path capacity satisfying the cell loss target rate based on the peak cell rate, the transition probabilities a and d, and the cell loss target rate. An ATM virtual path capacity setting device characterized by the above.