KR100226996B1 - High rate call permit control method and apparatus based on the traffic monitoring - Google Patents

Abstract

The present invention relates to a traffic monitoring-based fast call admission control device. The present invention compares the maximum cell rate with the amount of available available bandwidth when a call request having a maximum cell rate is made to determine whether to accept a connection and to determine a link capacity value. Call permission control means for outputting; Server means for obtaining a monitoring value for traffic corresponding to each class at a predetermined period from a link capacity value obtained by the call permission control means; And a capacity allocation control means for obtaining a cell distribution function based on the traffic monitoring value, calculating the available bandwidth, and returning the available bandwidth to the call permission control means, wherein the call is based on the maximum cell rate and the probability distribution function of the traffic. Efficient link use is possible for any traffic source while real-time control using admission control technique.

Description

Traffic monitoring based fast call control method and apparatus.

The present invention is based on the traffic monitoring for homogeneous traffic at the access control unit of an asynchronous transfer mode (ATM) exchange and only the highest peak cell rate (PCR) as a source provided parameter. The present invention relates to a traffic monitoring-based fast call permit control method and apparatus for performing use and call permission control to achieve both real-time increase of control and reduction of error through a quick comparison operation.

In general, it is a traffic control technique when implementing an Asynchronous switching mode (ATM) switching method, which is a recommended method to provide an B-Integrated Service Digital Network (ISDN) service, and is controlled in a wired network asynchronous transmission mode switch. It is equipped as an algorithm. In fact, these algorithms are commercialized in foreign countries and installed in their exchanges or only control algorithms are sold.

Typical call admission control (CAC) techniques currently used include call admission control based on equivalent bandwidth calculation and call admission control based on burst modeling.

In the call admission control method based on the former equivalent bandwidth calculation, this method approximates the bit rate occurring in the multiplexed connection to obtain the equivalent bandwidth, and then calls a new uneven connection when there is a connection request of a new call. It is a technique of determining whether to connect by determining whether the remaining bandwidth is exceeded.

The equivalent bandwidth means the minimum bandwidth that satisfies the requirements for the quality of service of the call, has a value larger than the average cell rate and a value smaller than the maximum cell rate.

There are various methods for calculating the equivalent bandwidth, and a representative method thereof is as follows.

It calculates the equivalent bandwidth for each call regardless of the capacity of the entire physical link, and then obtains the equivalent bandwidth for the entire traffic based on the queuing analysis.

The equivalent bandwidth of each call whose cell loss rate requirement threshold is epsilon is calculated as shown in Equation (1).

Where a = 1n ε, R _p is the maximum cell rate, ρ is the ratio of the average cell rate to the maximum cell rate, b is the average burst length, and x is the size of the buffer.

In this case, when n connections are multiplexed, the size C of the total bandwidth required is calculated as in Equation 2.

At this time, in order to consider the multiplexing effect, the size C of the total bandwidth is calculated as shown in Equation 3 by assuming Gaussian distribution for the aggregated traffic.

Where m _i is the average bit rate and σ _i ² is the variance.

In addition, in the call admission control method based on the latter burst modeling, the technique uses a peak bit rate (PBR) regardless of the distribution of on / off intervals of a cell arrival processor. ) And average bit rate (ABR) to determine whether a call is connected.

The probability that the number of bursts (bursts) in the on state at any instant when multiple virtual channels with the maximum bit rate (PBR) = R and the average bit rate (ABR) = a is multiplexed becomes k Equation 4

Therefore, when k virtual channels are multiplexed in a link, the probability that the required bandwidth is kR is assumed to be P (n, k).

In this case, if the acceptance of the connection is determined as the probability that the bandwidth used by the connected calls exceeds the threshold value, acceptance of the new call may be determined as shown in Equation 5 below.

This means that when the physical link bandwidth is C and the total number of connected calls including new calls is n, there is a probability that the amount of total bandwidth to be used by connected calls after the new call is connected will not exceed 90% of the physical link bandwidth. If it is less than the appropriate level (1-ε), the connection is allowed, otherwise it is rejected.

However, in the call admission control scheme based on the equivalent bandwidth calculation used in the asynchronous transfer mode (ATM) switching scheme described above, it is difficult to calculate the exact equivalent bandwidth of the individual call layer in advance, and the link utilization efficiency when the number of traffic sources is small. Not only does it have this disadvantage, but it has a problem in time and accuracy of calculating the total equivalent bandwidth, which makes it difficult to control in real time.

In addition, although the call admission control method based on burst modeling is simpler than the call admission control method based on the equivalent bandwidth calculation, in the heterogeneous traffic environment, the calculation is complicated and the relationship between burst traffic characteristics and quality of service is unclear. It has a disadvantage.

Accordingly, the present invention excludes a decrease in link utilization efficiency and computational complexity in a heterogeneous traffic environment in the conventional technique described above, and, in one aspect of the present invention, provides a maximum cell rate and a probability of traffic. It is an object of the present invention to provide a traffic monitoring-based fast call permit control method and apparatus for enabling efficient link use for arbitrary traffic sources while controlling in real time using a call permit control technique based on a distribution function.

In another aspect of the present invention, an object of the present invention is to increase the real-time control of the control by using only the maximum cell rate as a parameter provided by the traffic monitoring source.

In still another aspect of the present invention, an object of the present invention is to reduce the error of the controller and improve the utilization efficiency of the link, rather than the call admission control method based on the burst modeling.

Another aspect of the present invention is to prevent traffic over-entry in advance to prevent overload of the exchange.

In still another aspect of the present invention, an object thereof is to improve communication quality by reducing control time required for entering a call.

1 is a block diagram showing an embodiment provided in the description of the traffic monitoring-based high speed call permit control apparatus of the present invention

2 is a signal flow diagram for calculating an equivalent bandwidth in an exchange using the asynchronous transmission scheme of FIG.

3 is a signal flow diagram for call admission control of FIG.

<Description of the symbols for the main parts of the drawings>

100: input terminal 101: call control unit

101a: comparison unit 101b: available bandwidth calculation unit

102: server unit 103: capacity allocation control unit

103a: cell rate distribution determining unit 103b: effective available width determining unit

In accordance with an aspect of the present invention, a traffic monitoring-based fast call permit control apparatus according to an aspect of the present invention connects by comparing the maximum cell rate with the amount of available extra available bandwidth when a call having the maximum cell rate is requested. Call permission control means for determining whether to accept and outputting a link capacity value; Server means for obtaining a monitoring value for traffic corresponding to each class at a predetermined period from a link capacity value obtained by the call permission control means; And a capacity allocation control means for obtaining a cell distribution function based on the traffic monitoring value, calculating the available bandwidth based on the traffic distribution value, and returning it to the call permission control means.

A traffic monitoring-based high speed call permission control apparatus according to the present invention, wherein the call permission control means includes: comparison means for comparing the input maximum cell rate with the size of the available bandwidth obtained by the capacity utilization control means; And available bandwidth calculating means for calculating a new available bandwidth with the available bandwidth and the maximum cell rate obtained in the comparing means.

A traffic monitoring-based high speed call permission control apparatus according to the present invention, wherein the capacity allocation control means comprises: cell rate distribution determining means for obtaining a cell distribution function based on the traffic monitoring value obtained from the server means; And effective available bandwidth determination means for determining an available bandwidth based on the obtained cell distribution function and feeding back to the call permission control means.

In the traffic monitoring-based high speed call permission control apparatus according to the present invention, the available bandwidth calculating means obtains a new available bandwidth by subtracting the maximum cell rate from the previous available bandwidth.

According to another aspect of the present invention, there is provided a traffic monitoring-based fast call permission control method for achieving the above objects, including: receiving parameters required for an equivalent bandwidth calculation; Designating an upper limit and a lower limit of the equivalent bandwidth after inputting the parameter; Setting an intermediate value between an upper limit value and a lower limit value of the equivalent bandwidth; Calculating a cell loss rate in the corresponding update period of the equivalent bandwidth; Determining whether the calculated cell loss rate is less than or equal to a cell loss rate requirement condition; Outputting the calculated equivalent bandwidth when the determination result is less than or equal to the cell loss rate requirement condition; and adding the next cell to the calculation when the cell loss rate requirement is less than the limit value; Comparing the added cell loss rate with a cell loss rate requirement threshold and specifying a currently designated equivalent bandwidth as a lower limit if it is abnormal; Designating a currently designated equivalent bandwidth as an upper limit if the added cell loss rate is less than or equal to a cell loss rate requirement; And determining whether the number of counted cells is greater than a specified value after designating the lower limit value and the upper limit value, and repeating the steps after the upper limit value and the lower limit value specifying step and outputting an upper limit value of the currently designated equivalent bandwidth if the value is larger. It is done.

A traffic monitoring-based fast call admission control method for achieving the objects of the present invention, comprising: comparing a maximum cell rate of a new call with an available bandwidth available to a user in a communication network when a connection request of a new call is made; Rejecting a call connection if the comparison available bandwidth is less than a maximum cell rate; And if the available bandwidth is greater than the maximum cell rate, permitting the connection of the call and updating the available bandwidth.

Hereinafter, with reference to the accompanying drawings it will be described in detail a preferred embodiment of a traffic monitoring-based fast call permit control apparatus according to the present invention.

First, prior to the description of the present invention, the call permission controller should be capable of real-time control while enabling efficient link usage for any traffic source.

In order to satisfy both of these conditions, the present invention proposes a call admission control method based on the maximum cell rate (PCR) and the probability distribution function of traffic.

The proposed method uses only the maximum cell rate as a traffic parameter provided by the user.

The reason is that the average cell rate is not suitable as a traffic parameter for call admission control because it may be impossible for traffic sources to accurately estimate the average cell rate in the case of specific traffic.

In contrast, the maximum cell rate can be estimated relatively accurately.

However, if call admission control is performed based only on the maximum cell rate excluding the average cell rate, information on the traffic is insufficient. Therefore, the probability distribution function for the number of cells arriving during a certain measurement period is obtained through the actual measurement of the traffic.

From the probability distribution function obtained, the equivalent bandwidth used by the current traffic is estimated.

Thus, the proposed scheme accepts the connection if the maximum cell rate of the call is less than the available extra bandwidth when the new call has made a connection request, and otherwise refuses the connection.

In the technique of the present invention, as a parameter for providing a traffic source, the call admission control is performed using only the maximum cell rate, so that the structure of the controller is simpler than the call admission control scheme based on the equivalent bandwidth calculation, and the real-time control of the control is made through fast comparison. Increases.

In addition, the efficiency of the link can be improved by reducing the error of the controller compared to the call admission control method based on the burst modeling.

In addition, congestion in a computer communication network is caused when a larger amount of traffic flows than a traffic capacity that can be handled in a network, and may be caused by unpredictable fluctuations in traffic flow or failure in the network.

Among them, cell loss due to buffer overflow is the biggest source of error in the high-speed communication network environment where the error rate is very low such as asynchronous transmission mode (ATM) network.

Congestion in ATM networks can greatly degrade the quality of service, and a series of actions taken to minimize the effects of congestion is called congestion control.

Congestion control schemes that can be used in ATM networks are divided into two categories: preventive congestion control scheme and reactive congestion control scheme.

The preventive congestion control technique is a technique for performing appropriate control before traffic congestion occurs by predicting traffic conditions of a communication network.

In high-speed transmission protocols such as ATM, the performance of the preventive congestion control technique is reported to be superior to the adaptive congestion control technique.

One of the preventive congestion control techniques is the call admission control technique.

Call admission control is defined as a series of operations performed by a communication network to control a virtual channel connection (VCC) or a virtual path connection (VPC) during a call connection process.

The purpose of call admission control is to determine whether to connect a new call when there is a connection request, so as not to deteriorate the traffic occurring in the new call and the quality of service of the existing connected call.

The network user waits for the call connection decision after the user presents the parameter of the traffic and the quality of service information to the access controller of the access node.

At this time, call admission control should be able to control in real time and should be designed to have high link efficiency within the range that can guarantee the service quality of user traffic.

Accordingly, the call permission control method in the present invention proposes a control method capable of efficiently using a link for any traffic source with high real-time controllability for call control for uniform traffic.

In order to satisfy both of these conditions, the proposed scheme proposes a call admission control method based on the maximum cell rate (PCR) and the probability distribution function of traffic.

The proposed method uses only the maximum cell rate as a traffic parameter provided by the user.

This is because traffic sources can estimate the maximum cell rate relatively accurately compared to the average cell rate.

However, when call admission control is performed based on the maximum cell rate except the average cell rate, the information on the traffic is insufficient. Therefore, the probability distribution function for the number of cells arriving during a certain measurement period is obtained through the actual measurement of the traffic.

When the spread distribution function is obtained, the equivalent bandwidth used by the current traffic is estimated using the spread distribution function.

The available bandwidth, C _BW , can be easily calculated because it is equal to the difference between the current equivalent bandwidth and the available link capacity.

From this, when a new call has made a connection request, the new call compares the maximum cell rate with the amount of extra bandwidth available to determine whether to accept.

This will be described in detail with reference to FIG. 1.

1 is a block diagram showing an embodiment provided in the description of the traffic monitoring-based high speed call permit control apparatus of the present invention.

According to this embodiment, when there is a call request having the maximum cell rate R _P from the input terminal 100, the size of the maximum cell rate R _P and the available spare bandwidth C _BW is compared. A call value control unit 101 for determining whether to accept the connection and outputting a link capacity value, and a monitoring value for traffic corresponding to each class at a predetermined period from the link capacity value input from the call permission control unit 101. To obtain a cell distribution function based on the server unit 102 outputting through the output terminal 104 and the traffic monitoring value input from the server unit 102, and calculates the available bandwidth (C _BW ) based thereon. And a capacity allocation control unit 103 for feeding back to the call permission control unit 101.

In addition, the call permission controller 101 compares the maximum cell rate R _P input through the input terminal 100 with the size of the available bandwidth C _BW input from the capacity allocation controller 103. ) And an available bandwidth calculator 101b that calculates a new available bandwidth with the available bandwidth C _BW and the maximum cell rate R _P input from the comparator 101a.

The capacity allocation control unit 103 further includes a cell rate distribution determining unit 103a that obtains a cell distribution function based on the traffic monitoring value input from the server unit 102, and an available bandwidth based on the obtained cell distribution function. And a valid available bandwidth determination unit 103b for determining (C _BW ) and feeding back to the call permission control unit 101.

As such, in the case of the traffic monitoring-based high speed call permission control apparatus, first, if there is a call request having the maximum cell rate R _P from the input terminal 100, the comparison unit 101a of the call permission control unit 101 is then referred to. The acceptance rate of the connection is determined by comparing the maximum cell rate R _P with the size of the available bandwidth C _BW calculated by the capacity allocation control unit 103 to be described.

At this time, if the call is connected, the available bandwidth calculating unit 101b subtracts the maximum cell rate R _P from the calculated available bandwidth C _{BW to} recalculate the new available bandwidth C _BW and input it to the server unit 102. Done.

The server unit 102 obtains a monitoring value for traffic corresponding to each class at a predetermined time period from the link capacity value input from the available bandwidth calculating unit 101b, and outputs it through the output terminal 104, and the capacity allocation control unit ( To the cell rate distribution determining unit 103a.

The cell rate distribution determining unit 103a obtains a cell distribution function based on the traffic monitoring value input from the server unit 102 and provides the cell distribution function to the effective available bandwidth determining unit 103b.

The effective available bandwidth determining unit 103b calculates the available bandwidth C _BW based on the cell distribution function obtained by the cell rate distribution determining unit 103a and traces it to the call permission control unit 101.

That is, the above-described traffic measurement is an important measurement parameter in the case of actually measuring the traffic multiplexed on the link.

a) Renewal period: N

One update period consists of N measurement periods.

In other words, update after N measurements.

In the case of a long update period, the dynamic adaptability to the change of traffic is reduced, but the effect of time delay for calculating the bandwidth used is reduced.

On the other hand, if the update period is shorter, the adaptation is quicker due to the change in traffic, but the number of samples is reduced, which reduces the accuracy of probability distribution.

b) Measurement Reflection Ratio (MRR): a

This value is a weight that determines how much the value obtained through the actual measurement is reflected in the existing probability distribution function.

In the probability distribution function estimation, the probability that the number of K cells arrived during the measurement period S in the nth update period is called P (K; n).

Knowing this probability distribution function is best, but it is difficult to define accurately, so the estimate of this probability distribution function is p (k, n), which is given by Equation 6.

p (k, n +1) = aq (k, n) + (1-a) p (k, n)

R in Equation 7 denotes the maximum number of cells that can arrive during the measurement period and estimates the probability distribution function when the call with the maximum cell rate R _P is accepted as in Equation 8.

R = s.Rp

p (k, n + 1) = {p (k-R; n)}, k≥R

0 k <R

If the existing call multiplexed on the link is released, no action is taken for controlled simplification.

This wastes bandwidth for a while, but is actually calculated by the actual bandwidth.

Given the probability distribution function for the number of cells arriving during the measurement period s, the cell loss rate in the nth update period is given by Equation (9).

Where [X] ⁺ = {x, x≥ 0, x <0}

Using Equation 9, a bandwidth satisfying a limited cell loss rate may be obtained.

In the equivalent bandwidth calculation, a service requirement for a cell loss rate of a user for all traffic is defined as ε.

If the probability distribution function of the number of cells to be transmitted in the (n + 1) th update period during the measurement period s is given the estimated value p (k, n + 1), the equivalent bandwidth C 'used by the traffic can be calculated from this. have.

The proposed algorithm for calculating the equivalent bandwidth is shown in FIG.

The calculation of the equivalent bandwidth in detail with reference to FIG. 2 is as follows.

First, parameters necessary for calculating the equivalent bandwidth are received (step ST100).

Here, the parameter P means the maximum value and A means the average value.

In the case of the variable bit rate (VBR) service, the equivalent bandwidth is determined between the average cell rate and the maximum cell rate, so that P is set as the upper limit b and A is the lower limit a as an initial value (step ST101).

Then, an intermediate value between the lower limit a and the upper limit b is set to the equivalent bandwidth (step ST102).

Thereafter, the cell loss rate in the update period is calculated (step ST103).

If the calculated cell loss rate is ε, the process proceeds to step ST105. If the cell loss rate is not ε, the process proceeds to step ST106.

In the step ST105, if the cell loss rate is ε, the calculated equivalent bandwidth is a critical value, and thus C 'is output and terminated.

In step ST106, if the cell loss rate is not ε, the next cell is added to the calculation.

If the cell loss rate is greater than [epsilon] at step ST107, the process proceeds to ST108.

In step ST108, if the cell loss rate is greater than ε, since the currently designated equivalent bandwidth is under estimated compared to the actual traffic, the current equivalent bandwidth is designated as the lower limit, and then the process proceeds to step ST110.

In step ST109, if the cell loss rate is smaller than ε, since the currently designated equivalent bandwidth is over estimated compared to the actual traffic, the current equivalent bandwidth is designated as the upper limit and then the process proceeds to step ST110.

In step ST110, if the number of cells counted so far is smaller than the specified value N, the process after step ST101 is repeated. If the number of cells counted so far is greater than the specified value N, one update period ends. The process is regarded as having been completed and the process proceeds to step ST111.

In the above step ST111, since the currently specified upper limit value b becomes the equivalent bandwidth in the state where the update period is terminated in one, the value b is outputted and ends.

In addition, in the connection acceptance control scheme, it is assumed that one update period is performed as a unit.

This gives the probability distribution function for the bandwidth used by the currently connected traffic, the bandwidth available to the user, and the number of cells at the start of the nth update period.

If a connection request for a new call comes in, the network compares the maximum cell rate of the new call with the available bandwidth available to the user.

If the available bandwidth is greater than the call's maximum cell rate, the call is allowed to connect. If the available bandwidth is less than the call's maximum cell rate, the call is rejected.

This will be described in detail with reference to FIG. 3.

That is, when a connection request of a new call comes in, the communication network compares the new maximum cell rate R _P with the available bandwidth C _BW available to the user (step ST112).

If the available bandwidth is greater than the maximum cell rate as a result of the comparison in step ST112, the process proceeds to step ST114.

If the available bandwidth is smaller than the maximum cell rate, the process proceeds to step ST113.

In step ST14, if the available bandwidth is larger than the maximum cell rate of the call, the connection of the call is allowed.

In step ST113, if the available bandwidth is less than the maximum cell rate of the call, the connection is rejected and terminated.

Then, when the connection of the new call is allowed, the available bandwidth C _BW is updated (step ST115).

As described above, in the present embodiment, an effective link can be used for any traffic source while performing real-time control using a call permission control method based on the maximum cell rate and the probability distribution function of the traffic.

And while specific embodiments of the present invention have been described and illustrated above, it is a matter of course that the present invention may be embodied in various modifications by those skilled in the art.

Such modified embodiments should not be understood individually from the spirit or point of view of the present invention, and such modified embodiments shall fall within the appended claims of the present invention.

As described above, the present invention enables efficient link use for arbitrary traffic sources while controlling in real time using a call admission control method based on a maximum cell rate and a probability distribution function of traffic through relatively simple hardware. Overload can be prevented in advance to prevent overload of the exchange, and through the simple comparison operation, the communication quality can be improved by reducing the control time required for entering a call.

Claims (6)

Call permission control means for determining whether to accept the connection by outputting a link capacity value by comparing the maximum cell rate with the size of the available spare bandwidth when the call having the maximum cell rate is requested; Server means for obtaining a monitoring value for traffic corresponding to each class at a predetermined period from a link capacity value obtained by the call permission control means; And a capacity allocation control means for obtaining a cell distribution function based on the traffic monitoring value, calculating the available bandwidth, and returning the available bandwidth to the call permission control means. 2. The apparatus of claim 1, wherein the call permission control means comprises: comparison means for comparing the input maximum cell rate with the size of the available bandwidth obtained by the capacity allocation control means; And an available bandwidth calculating means for calculating a new available bandwidth with the available bandwidth and the maximum cell rate obtained by the comparing means. 2. The apparatus of claim 1, wherein the capacity allocation control means comprises: cell rate distribution determining means for obtaining a cell distribution function based on a traffic monitoring value obtained from the server means; And a valid available bandwidth determining means for determining an available bandwidth based on the obtained cell distribution function and returning it to the call permission controlling means. 3. The apparatus of claim 2, wherein the available bandwidth calculating means obtains a new available bandwidth by subtracting a maximum cell rate from a previous available bandwidth. Receiving parameters necessary for calculating an equivalent bandwidth; Designating an upper limit and a lower limit of the equivalent bandwidth after inputting the parameter; Setting an intermediate value between an upper limit value and a lower limit value of the equivalent bandwidth; Calculating a cell loss rate in the corresponding update period of the equivalent bandwidth; Determining whether the calculated cell loss rate is less than or equal to a cell loss rate requirement condition; Outputting the calculated equivalent bandwidth when the determination result is less than or equal to the cell loss rate requirement condition; and adding the next cell to the calculation when the cell loss rate requirement is less than the threshold value; Comparing the added cell loss rate with a cell loss rate requirement threshold and specifying an equivalent and currently designated equivalent bandwidth as a lower limit; Designating a currently designated equivalent bandwidth as an upper limit if the added cell loss rate is less than or equal to a cell loss rate requirement; Determining whether the number of counted cells is greater than a specified value after designating the lower limit value and the upper limit value, and repeating the steps after the upper limit value and the lower limit value specifying step and outputting an upper limit value of the currently designated equivalent bandwidth if the value is larger. Traffic monitoring based fast call admission control method. Searching whether there is a connection request of the new call and comparing the maximum cell rate of the new call with the available bandwidth available to the user in the communication network when the request is made; Rejecting a call connection if the available bandwidth is less than the maximum cell rate; And if the available bandwidth is greater than the maximum cell rate, allowing the connection of the call and updating the available bandwidth.

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