JP3088975B2 - Connection acceptance determination method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM (Asynchronou).
s Transfer Mode). The present invention relates to a technique for determining connection acceptance in an ATM exchange.

[0002]

2. Description of the Related Art Different from an STM (Synchronous Transfer Mode) exchange in which a transmission slot is designated in a frame and a band is deterministically assigned to each connection, in an ATM exchange, each connection transfers a cell at an arbitrary time. Can be sent. In the ATM exchange, when a connection is set, a traffic descriptor of the connection is declared, and it is determined whether or not the connection can be accepted so that cell loss does not occur.

[0003] The main place where a cell loss occurs in an ATM exchange is that an ATM is transmitted to a VP (Virtual Path).
This is the output buffer of the exchange. A simple cell transmission method follows an algorithm in a FIFO (First in first out) output buffer.

[0006] There is a cell read timing every one cell time, and at the read timing, if there is a cell in the buffer, the first cell in the buffer is read.

[0005] Peak rate, average rate, burstiness, peak duration, source type (eg, telephone, video), etc., are considered as possible traffic descriptors.

When it is determined whether or not a connection can be accepted using only the peak speed, when the burstiness of cell transmission from each connection is strong (the ratio between the average speed and the peak speed is large), the band use efficiency can be sufficiently increased. This causes a problem (hereinafter, the method of performing band operation based on the peak cell rate in this manner is referred to as a peak allocation method).

[0007] As one solution to this problem, Saito
(H.Saito, "Call Admission Control in an ATM Network
Using Upper Bound of Cell Loss Probability, "IEEE
TransCommun, vol. 40, no.9, pp. 1512-1521, Sep. 1992.) We have proposed a method to determine whether to accept a connection.

[0008] Saito's method is based on the peak rate R _i (maximum number of cells transmitted in γ cell time) and the average rate A _i (average number of cells transmitted in γ cell time) at each connection i declared by the user. , The cell loss rate P _clr is:

[0009]

(Equation 1) Is estimated by Connection i (i = 1,..., N)
Is a connection already accommodated in the VP, and connection n + 1 is a connection newly requested to be connected. * Is a convolution integral. Fixed window length γ
Is γ ≦ K + 1, where K is the buffer size.

FIGS. 8 and 9 show a conventional connection acceptance judging device. FIG. 8 is a conceptual diagram illustrating the function of the connection acceptance determination device. FIG. 9 is a block diagram of a main part of a conventional connection acceptance determination device. As shown in FIG. 8, the connection acceptance determination device 1 is installed in an ATM exchange and determines whether a connection set in a VP can be accepted.

As shown in FIG. 9, the conventional connection acceptance determining device 1 comprises a user report parameter unit 10, a cell loss rate estimating unit 11, and a connection acceptance determining unit 12. The user report parameter unit 10 has a memory for storing a peak speed and an average speed for each connection reported by the user.

FIG. 10 shows a conventional connection acceptance determination algorithm. When a connection request for a new connection is generated (S0), the peak speed R _{n + 1} and the average speed A _{n + 1 of} the new connection and the peak speed and the average speed of the connection already accommodated in the VP are determined (S1). ,
The cell loss rate P _clr is estimated using the equation (2) (S
2). Assuming that CLR is a specified value of the cell loss rate, P _clr <C
If it is an LR (S3), the connection is accepted (S3).
4). Otherwise, the connection is not accepted (S5).

[0013]

The conventional connection admission judgment device requires parameters of a peak speed and an average speed from the user. However, it is difficult for the user to declare the average speed before setting up the connection.

If the user reports more than the actual average rate, the cell loss rate is estimated to be larger than the actual rate. Despite the fact that the actual cell loss rate is smaller than the specified value, no connection is accepted and network resources cannot be used effectively.

If the user reports lower than the actual average rate, the UPC (Usage Paramet
er Control), it is not possible to transfer a cell flow higher than the average speed in the network, so that high-speed communication information cannot be transferred.

The present invention has been made in such a background, wherein a user declares only the peak rate of cell transfer,
It is an object of the present invention to provide a method and an apparatus for judging connection acceptance, in which an ATM exchange can determine a user's average speed by measurement without making a report on the average speed, and can judge connection acceptance. SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for judging connection acceptance which can flexibly cope with traffic fluctuation. The present invention
An object of the present invention is to provide a method and an apparatus for judging connection acceptance that can eliminate the need to report the average speed of cell transfer performed in response to a connection connection request and can reduce the load on the user.

[0017]

The most important feature of the present invention is to determine the average cell speed by measuring the number of cell arrivals of the connection to be accommodated. Conventionally, the user has had to declare the average speed A _i of the cell transfer as traffic descriptors, in the present invention the network side determines the average speed A _i by periodic measurement. This allows
It is possible to make an adaptive connection acceptance determination that can flexibly cope with traffic fluctuations.

That is, a first aspect of the present invention is a connection admission determination method, which estimates a cell loss rate according to a peak rate and an average rate of cell transfer occurring in connection with a new connection, and calculates the cell loss rate. Is a connection admission judgment method for accepting this new connection connection when does not exceed a prescribed value of the cell loss rate. It is a feature of the present invention that the average speed is obtained in accordance with the result of measuring the number of cells arriving at a connection to be accommodated.

The average rate is A _i (t), the average rate within the γ cell time at time t, T is the measurement period of the number of cells arriving at the connection to be measured, ΔT is the measurement interval,
The number of cells arriving within the T cell time at time t is B
and _i (t), when the smoothing coefficient _{α, A i (t) =} (1-α) A i (t-ΔT) + α (γ /
T) It is desirable to obtain it as B _i (t). However, 0 ≦ α ≦ 1.

Thus, it is possible to determine the average rate regardless of the report from the user, thereby estimating the cell loss rate and making a connection acceptance judgment. Therefore, it is not necessary for the user to declare the average speed, and the connection acceptance can be determined according to the accurate data measured on the network side.

The number of connections to be measured can be detected, and the measurement period T and the measurement interval ΔT can be set adaptively according to the detection result.

According to this, the load required for measurement can be kept constant regardless of the number of already set connections. That is, when the number of connections to be measured is large, the measurement interval ΔT is increased and the measurement period T
, The load of hardware related to the measurement can be reduced. When the number of connections to be measured is small, high-precision measurement can be performed by reducing the measurement interval ΔT and increasing the measurement period T.

According to a second aspect of the present invention, there is provided a connection admission determining apparatus for estimating a cell loss rate according to a peak rate and an average rate of cell transfer occurring with a new connection connection, Means for accepting this new connection connection when does not exceed a prescribed value of the cell loss rate. It is a feature of the present invention that the estimating means includes means for calculating the average speed in accordance with the result of measuring the number of cells arriving for the connection to be accommodated.

The means for obtaining the average speed is defined as A _i (t), the average speed within the γ cell time at time t, T as the measurement period of the number of cells arriving at the connection to be measured, ΔT as the measurement interval, and t at time t. When the number of cells arriving within the T cell time is B _i (t) and the smoothing coefficient is α, A _i (t) = (1−α) A _i (t−ΔT) + α (γ /
T) It is desirable to include a means for obtaining B _i (t). Where 0 ≦
α ≦ 1.

It is preferable that the apparatus further comprises means for detecting the number of connections to be measured, and means for adaptively setting the measurement period T and the measurement interval ΔT according to the detection result.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a main part of a connection acceptance determination device common to the first and second embodiments of the present invention. FIG. 2 is a block diagram of a main part of the arrival cell number measuring unit according to the first embodiment of the present invention. FIG. 5 is a block diagram of a main part of an arrival cell number measuring unit according to a second embodiment of the present invention.

The present invention provides a cell loss rate estimating unit 11 for estimating a cell loss rate according to a peak rate and an average rate of cell transfer generated in connection with a new connection, and the cell loss rate is defined by a predetermined cell loss rate. If the value does not exceed the value, the connection acceptance determining device 1 includes a connection acceptance determining unit 12 that receives the new connection.

Here, a feature of the present invention is that the cell loss rate estimating unit 11 obtains the average speed according to the result of measuring the number of cells arriving for the connection to be accommodated.

The cell loss rate estimating unit 11 sets the average speed within the γ cell time at time t to A _i (t), the measurement period of the number of cells arriving at the connection to be measured to T, the measurement interval to ΔT, and the time t When the number of cells arriving within the T cell time is B _i (t) and the smoothing coefficient is α, A _i (t) = (1−α) A _i (t−ΔT) + α (γ /
T) Find the average speed as B _i (t). However, 0 ≦ α ≦ 1.

The second embodiment of the present invention comprises a memory 15 for measuring the number of connections to be measured for detecting the number of connections to be measured,
A measurement period T determiner 16 and a measurement interval ΔT determiner 17 that adaptively set the measurement period T and the measurement interval ΔT according to the detection result are provided.

[0031]

【Example】

(First Embodiment) FIG. 1 shows a connection acceptance determining apparatus according to a first embodiment of the present invention. The connection acceptance determination device of the present invention includes a user report parameter unit 2, an arrival cell number measurement unit 3, an average speed calculation unit 4, an average speed memory 5, a cell loss rate estimation unit 11, and a connection acceptance determination unit 12.

FIG. 2 shows a block configuration of the arrival cell number measuring unit 3. FIG. 3 shows the concept of measuring the number of cells arriving at a connection. The cell arrival measurement is performed, for example, at the entrance of the output buffer for each VP. In measuring the number of cells arriving for each connection, a measurement period T and a measurement interval ΔT are determined in advance, and are recorded in the measurement period memory 6 and the measurement interval memory 7. FIG. 3 shows the measurement of the number of arriving cells for connection i when T = ΔT. In practice, the number of arriving cells is measured for the accommodated connection. At time t, the number of cells arriving within the T cell time is represented by B _i (t).

At time t, the average speed A _i (t) (average number of cells transmitted in γ cell time) is A _i (t) = (1−α) A _i (t−ΔT) + α (γ / T) B _i (t)... (4) Here, α is a smoothing coefficient, and 0 ≦ α ≦ 1. When α is small, the ratio of measurement results close to the present is small, and short-term fluctuations can be removed. When α is large,
The proportion of measurement results close to the present is large and reflects short-term fluctuations.

In this way, the average speed A _i (t) (i = 1,..., N) can be obtained by measuring the number of arriving cells for each connection already accommodated. This value A _i (t) is written to the average speed memory.

The average speed A _{n + 1} of the connection n + 1 for a new connection request is A _{n + 1} = P _{n + 1} . However, when a new connection is accepted, the average speed is updated based on the measurement result by the equation (2).

FIG. 4 shows a connection acceptance determination algorithm according to the first embodiment of the present invention. When a new connection request for connection occurs (S0), reads out the peak rate R _i of a connection that has already been accommodated by the user declared parameter section 2 (S10). Further, the average speed A _i of the already accommodated connection is read from the average speed memory 5 (S
11). Average speed A _{n + 1} of the new connection request connection n + 1 is the A n _{+ 1} = P n _{+ 1.} However, when a new connection is accepted, the average speed is updated based on the measurement result by the equation (2). The peak speed P _{n + 1} of the new connection is declared by the user.

Based on these information, using equation (2),
The cell loss rate P _clr is estimated (S2). Assuming that CLR is a specified value of the cell loss rate, if P _clr <CLR, (S
3), accept a connection (S4). Otherwise, the connection is not accepted (S5).

Conventionally, the user had to declare the average speed A _i as a traffic descriptor, but in the present invention, the network side can determine the average speed A _i by periodic measurement.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a block diagram of a main part of the arrival cell number measuring unit 3 according to the second embodiment of the present invention. FIG. 6 is a diagram showing the concept of the measurement period T and the measurement interval ΔT when the number of connections to be measured is large. FIG. 7 is a diagram illustrating the concept of the measurement period T and the measurement interval ΔT when the number of connections to be measured is small.

In the first embodiment of the present invention, the measuring period T and the measuring interval ΔT are fixed in the number-of-arrived-cells measuring section 3. In the second embodiment of the present invention, the number-of-arrived-cells measuring unit 3 includes a number-of-connections-to-be-measured memory 15, a measuring period T determining unit 16, a measuring interval ΔT determining unit 18, and a cell counter unit 8, as shown in FIG. I have. The measurement period T and the measurement interval ΔT are determined according to the number of accommodated connections.

For example, when the number of accommodated connections is large, measuring the number of arriving cells for each connection requires a large amount of hardware. Therefore, the measurement period T and the measurement interval ΔT are changed. For example, if the number of accommodated connections increases, as shown in FIG.
Increase the value of / T. If ΔT / T increases, the load of hardware involved in measurement per connection decreases, and even if the number of connections increases, the amount of hardware for measuring the number of cells arriving for the entire connection can be reduced. it can.

On the other hand, when the number of accommodated connections is small, the value of ΔT / T is reduced as shown in FIG. Even if ΔT / T is small, when the number of connections is small, the amount of hardware for measuring the number of cells arriving for the entire connection does not increase.

As described above, since the measurement period T and the measurement interval ΔT are determined according to the number of accommodated connections, there is no problem that the amount of hardware increases even if the number of connections increases.

(Third Embodiment) In the first embodiment of the present invention, the cell loss rate P _clr after accepting a new connection is estimated using the equation (2). And Aida et al. (M. Aida and T. Kubo, "Efficient Ce
ll-Loss Ratio Estimation for Real-Time CACDecision
s, "IEICE Trans.Commun., vol.E79-B, no.2, pp.108-115, F
eb. 1996.), and Murase et al.
se, H.Suzuki, S.Sato and T.Takeuchi, "A Call Admissio
n Control Estimate, "IEEE Journal of Selected Areas
in Communications, vol. 9, no. 9, pp. 1461-1470, Apr. 199
It can also be calculated using the method proposed in 1.). In any of these methods, the cell loss rate can be estimated using the peak speed P _i and the average speed A _i for each connection as input parameters. However, in the present invention, as in the first embodiment of the present invention, the user need only declare the peak speed P _i as the traffic descriptor, and does not need to declare A _i . A _i is determined by the network by periodic measurement.

The third embodiment of the present invention differs from the first embodiment of the present invention only in the equation used for estimating the cell loss rate. Here, Aida's method will be described. The formula for estimating the cell loss rate is

[0046]

(Equation 2) However, the equation (6) can be used because C ₃ > 0
When C ₃ ≦ 0, another equation is used. The reason for this is not directly related to the present invention and will not be described in detail here, but is described in the literature (T. Murase, H. Suzuki, S. Sat.
o and T. Takeuchi, "A Call Admission Control Estimat
e, "IEEE Journal of Selected Areas in Communication
s, vol. 9, no. 9, pp. 1461-1470, Apr. 1991.).

[0047]

As described above, according to the present invention,
The user can declare only the peak cell transfer rate, and the ATM exchange can determine the user's average rate by measurement without making a report of the average rate, and can judge connection acceptance. This makes it possible to flexibly respond to traffic fluctuations. In addition, it is not necessary to report the average speed of cell transfer performed in response to a connection request, and it is possible to reduce the load on the user.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of a connection acceptance determination device of the present invention.

FIG. 2 is a block diagram of a main part of an arrival cell number measuring unit according to the first embodiment of the present invention.

FIG. 3 is a diagram showing the concept of measuring the number of cells arriving at a connection.

FIG. 4 is a diagram showing a connection acceptance determination algorithm according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a main part of an arrival cell number measuring unit according to a second embodiment of the present invention.

FIG. 6 is a diagram showing the concept of a measurement period T and a measurement interval ΔT when the number of connections to be measured is large.

FIG. 7 is a diagram illustrating the concept of a measurement period T and a measurement interval ΔT when the number of connections to be measured is small.

FIG. 8 is a conceptual diagram illustrating functions of a connection acceptance determination device.

FIG. 9 is a block diagram of a main part of a conventional connection acceptance determination device.

FIG. 10 is a diagram showing a conventional connection acceptance determination algorithm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Connection acceptance determination device 2, 10 User report parameter part 3 Arrival cell number measurement part 4 Average speed calculation part 5 Average speed memory 6 Measurement period memory 7 Measurement interval memory 8 Cell counter part 11 Cell loss rate estimation part 12 Connection reception determination part 15 Memory for the number of connections to be measured 16 Measurement period T determining unit 17 Measurement interval ΔT determining unit

Continuation of the front page (72) Inventor Kohei Shiomoto Nippon Telegraph and Telephone Corporation 3-9-1-2 Nishishinjuku, Shinjuku-ku, Tokyo (56) References JP-A-7-177149 (JP, A) 8-237264 (JP, A) IEICE Transactions B- ▲ I 情報 Vol. J80-B-I No. 12 pp. 950-960 (December 25, 1997) IEICE Technical Report SS E94-243 (March 15, 1995) IEICE Technical Report SS E96-34 (August 19, 1996) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/28 H04L 12/56

Claims (2)

(57) [Claims] 1. Generated with a new connection connection
Cells according to peak and average cell transfer rates
The loss rate is estimated, and this cell loss rate is
If the fixed value is not exceeded, this new connection
In the connection acceptance determination method to be accepted, the average speedIs the average speed within the γ cell time at time t.
Degree A _i (T), the connection to be measured already accommodated
T is the measurement period of the number of arriving cells with respect to
The number of cells arriving within the T cell time at time t is B
_i (T) and the smoothing coefficient is α, A _i (T) = (1−α) A _i (T−ΔT) + α (γ /
T) B _i (T) Where 0 ≦ α ≦ 1 As Detect the number of connections to be measured, and
Therefore, the measurement period T and the measurement interval ΔT
Set adaptively Connection acceptance determination characterized by the following:
Method. (2)Occurs with a new connection
Cells according to peak and average cell transfer rates
Means for estimating the loss rate, and the cell loss rate
If the loss rate does not exceed the specified value, this new connection
Connection acceptance determination with means for accepting connection connections
In the device, The estimating means includes an estimating means for each connection already accommodated.
Calculate the average speed according to the result of the number of arrival cells
Including means, The means for obtaining the average speed is obtained when the γ cell at time t
The average speed within _i (T) and the connection to be measured
T is the measurement period of the number of arriving cells with respect to
The number of cells arriving within the T cell time at time t is B
_i (T) and the smoothing coefficient is α, A _i (T) = (1−α) A _i (T−ΔT) + α (γ /
T) B _i (T) Where 0 ≦ α ≦ 1 Including means to ask for, Means for detecting the number of connections to be measured;
According to the result The measurement period T and the measurement interval
Means for adaptively setting ΔT. Characterized by
To Connection acceptance judgmentapparatus.