JP2768100B2 - Burst traffic control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burst traffic control system for accommodating burst traffic in a network so as to satisfy the quality required by a user.

[0002]

2. Description of the Related Art At present, an asynchronous transfer system (ATM) for transferring information by dividing information into fixed lengths called cells is attracting attention as a core transmission switching system for accommodating bursty traffic. However, many problems are piled up in the traffic control system that guarantees the quality such as cell discard of the user. On the other hand, conventionally, a long-term average of the cell loss rate has been mainly studied. However, even if only a long-term loss rate is guaranteed, if the loss is large in the short term, it may not be possible to satisfy the user's request. Therefore, a traffic control technique that considers a short-term cell loss phenomenon is required.

[0003] On the other hand, Yamada et al.
Loss Behavior in Statist
Ial Multiplexer with Bur
Sty Input ", International
Conference on the Perform
ance of Distributed system
ms and integrated communi
site networks (Sep 199
In 1), the short-term cell loss rate in the state where overflow occurs in the short term, the duration thereof, and the time during which no overflow occurs are approximately derived using the MMPP model.

[0004]

The method by Yamada et al.
It is limited to a single call type condition, and its calculation procedure is very complicated because it assumes a buffer model.
Therefore, it cannot be applied to the case of a plurality of call types, and it is difficult to use it for actual traffic input regulation control due to the long actual calculation time.

An object of the present invention is to provide a short-term cell discard rate in a short-term overflow, a short-term cell discard rate in a call type, a duration of an overflow, and a duration of an underflow in which no overflow occurs in a case of a plurality of call types. It is an object of the present invention to provide a simple burst traffic control system which can provide a means that can be evaluated to a certain value range.

[0006]

According to a first aspect of the present invention, when a burst call of a plurality of call types is multiplexed on a link having a capacity C in an asynchronous transfer network, cells are continuously discarded. In the burst traffic control method for evaluating the drop rate Pov and controlling the input of burst traffic so that the drop rate Pov becomes a certain value or less, a random variable representing a sum of arrival speeds of simultaneously arriving bursts on the link is R, and a link capacity C The short-term cell loss rate Pov is obtained by dividing the average of the overflow rates RC in the period of R> C by the average of R in the period of R> C.
Is evaluated.

According to a second aspect of the present invention, when a plurality of burst calls are multiplexed on a link having a capacity C in an asynchronous transfer network,
Estimate the call type short-term cell discard rate Pov_j of the j-th call type during the overflow period in which cells are continuously discarded,
In a burst traffic control method for restricting the input of burst traffic so that this value is equal to or less than a certain value, when a random variable representing the sum of arrival speeds of simultaneously arriving bursts on the link is represented by R, the entirety in a period where R> C is satisfied. , The overflow speed O of the j-th call type among the overflow speeds RC
The method is characterized in that the average of v_j is obtained, and this is divided by the average of the arrival rates R_j of the j-th call type in the period where R> C, to evaluate the short-term cell discard rate Pov_j of the call type.

A third invention provides a method for multiplexing burst calls of a plurality of types on a link having a capacity C in an asynchronous transfer network.
In a burst traffic control method for evaluating a period E {T} at which an overflow condition in which cells are continuously discarded and restricting burst traffic input to a value equal to or greater than a certain value, arrival of simultaneously arriving bursts on the link Let R be a random variable representing the sum of speeds, let S be each state where R ≦ C, and let λs be the transition probability of transition from state S to the state of R> C. Of the period E
It is characterized by evaluating {T}.

A fourth invention provides a method for multiplexing burst calls of a plurality of types on a link having a capacity C in an asynchronous transfer network.
In a burst traffic control method for evaluating the duration E {O} of an overflow state in which cells are continuously discarded and restricting the input of burst traffic so that it becomes a certain value or less, arrival of simultaneous arrival bursts on the link Let R be a random variable that represents the sum of speeds.
The larger probability P {R> C} and E in the third invention
The duration E {O} is evaluated by multiplying by {T}.

A fifth invention provides a method for multiplexing burst calls of a plurality of types on a link having a capacity C in an asynchronous transfer network.
In a burst traffic control method for evaluating the duration E {U} of an underflow state in which no cells are continuously discarded and controlling the input of burst traffic so that the value becomes a certain value or more, arrival of simultaneous arrival bursts on the link Assuming that a random variable representing the sum of speeds is R, the probability that R is smaller than C, P {R ≦ C}, and E in the third invention
By multiplying by {T}, the duration time EU is evaluated.

In a sixth aspect of the present invention, when a plurality of burst calls are multiplexed on a link having a capacity C in an asynchronous transfer network, the number of multiplexed burst calls, peak rate, average rate, burst duration, and burst interval are N, Peak. , Avg, To
When n, the duration E {U} in which an underflow state in which no cells are continuously discarded occurs is calculated by using a formula E {U} = (Ton / Plong) × Peak ² / (N × AVG × (C-Peak)) or E {U} = (Ton / Plong) × Peak ² / C ² , and the input restriction of the burst traffic is performed so that this becomes a certain value or more. .

[0012]

The present invention provides a bufferless model for the short-term cell discard rate at the time of short-term overflow, short-term cell discard rate at call type, duration of overflow, and duration of underflow without overflow. By using, a means that can be easily evaluated can be provided.

Further, by providing a simple evaluation means,
A traffic control method that guarantees a user's cell discard quality requirement can be realized more easily.

[0014]

FIG. 1 shows a traffic arrival state on a link in an asynchronous transfer system to which the present invention is applied and a burst traffic control device for regulating the traffic arrival state. Let C be the capacity of link 10. Reference numeral 20 denotes a traffic control device, which is a traffic parameter of each call, such as a peak rate, an average rate, an average burst duration, and an average burst arrival interval Pe.
Input control is performed using ak_j, Avg_j, Ton_j, and Toff_j so as to satisfy the cell discard requirement for each burst call. Nj is the number of calls of the burst call type in which these parameters are the same.

Here, Peak_j, Avg_j, Ton
_J and Toff_j are defined as shown in FIG. FIG. 2 shows a state where the cell is divided into cells on the link having the link capacity C. The peak rate is the cell length when the burst is on /
Defined by cell arrival interval. Ton is the time during which the burst continues, and Toff is the burst interval. The average rate is Avg = Ton / (Ton + Toff) × Pe
ak.

The input restriction of the burst includes the cell loss rate in the overflow state in FIG. 1, the overflow period length,
This is performed based on the underflow period length in which no overflow has occurred.

FIG. 3 shows the configuration of the traffic control device 20. The quality evaluator 30 calculates a multiplex quality Q (P) based on the traffic parameters P for the K call types. The determination unit 40 calculates whether the value is larger or smaller than a specified value Th. As a result, if the specified value condition is not satisfied, input restriction is performed.

This input restriction is as follows: 1) When the traffic parameters of the input traffic are known in advance at the time of designing the network, long-term control by setting the traffic limit in advance; Medium-term control that declares parameters to the network and regulates call acceptance based on the parameters. 3) The network monitors traffic parameters during burst call communication, and based on this, controls burst calls during communication. This is achieved by any short-term control that regulates the peak rate or the average rate.

Here, n_j is a random variable representing the number of simultaneous arrival bursts of call type j.
It is assumed that 0 ≦ n_j ≦ Nj.

The sum of the peak rates of bursts arriving at the same time is represented by R and is represented by the following equation.

[0021]

(Equation 1)

The probability that each burst call type j is transmitting an n_j call burst is represented by P (n_j) and is represented by the following equation.

P (n_j) = N_j Cn_j (Avg_j / Peak_j) ^n_j × (1−Avg_j / Peak_j) ^(N_j-n_j) (1) Now, when the phenomenon that the burst overflows from the link is ^{captured by the accessless} model, the overflow state becomes R> C. Conventionally, quality has been evaluated only by the long-term cell loss rate Plong expressed by the following equation.

[0024]

(Equation 2)

In the present invention, the following six quality specifications Q (P)
give.

The first method uses the short-term cell loss rate Pov during the overflow period in which cells are continuously dropped as the multiplex quality Q (P), which is given by the following equation.

[0027]

(Equation 3)

The input of the burst traffic is regulated so that it becomes equal to or less than a predetermined value.

Here, the second method uses the call type short term cell discard rate Pov_j of the call type j during the overflow period in which cells are continuously discarded as the multiplex quality Q (P). Given by

[0030]

(Equation 4)

[0031] Burst traffic input regulation is performed so as to keep this below a certain value.

Here, the third method uses a period E {T} in which an overflow state in which cells are continuously discarded occurs as the multiplex quality Q (P), and is given by the following equation.

[0033]

(Equation 5)

Where A: R ≦ C and any n_j is replaced with n_j + 1 (<N_j +
1), then R> C (n_1, n_
(2 ,,, n_K) B: By setting n_k to n_k + 1 (<N_j + 1) with R ≦ C, k λn_j = (N_j−n_j) / Toff_j (5) that satisfies R> C. Restricts burst traffic input.

Here, the fourth method uses the duration E {O} of the overflow state in which cells are continuously discarded as the multiplex quality Q (P), and is given by the following equation.

E ｛O｝ = E ｛T｝ P ｛R> C｝ where

[0037]

(Equation 6)

The input of the burst traffic is restricted so that it becomes equal to or less than a predetermined value.

Here, the fifth method uses the duration E {U} of the underflow state in which no cells are continuously discarded as the multiplex quality Q (P), and is given by the following equation.

E ｛U ｛= E ｛T｝ × (1-P ｛R> C｝) where

[0041]

(Equation 7)

The input of the burst traffic is regulated so that it becomes a certain value or more.

Here, the sixth method uses the long-term cell discard rate Plong given by equation (2) as the duration E {U} of the underflow state in which no cells are continuously discarded as the multiplex quality Q (P). Approximate evaluation is given by the following equation.

EU ｛= (Ton / Plong) × Peak ² / (N × AVG × (C-Peak)) (8) or EU ｛= (Ton / Plong) × Peak ² / C ² ( 9) Here, Ton, Peak, N, and AVG are traffic parameters of a single call type. That is, in the case of burst traffic of a plurality of call types, it is obtained by approximately converting parameters from a plurality of call type models to a single call type model by extracting parameters of a representative burst call type.

The sixth method is characterized in that the underflow period length can be calculated very easily if the long-term cell loss rate Plong used in the normal quality regulation is obtained. FIG. 4 shows the approximation accuracy in this case. The thin line is the exact solution obtained by equation (7), and the dotted line is equation (8). Equation (8) is in good agreement with the exact solution and can be evaluated on the safe side. Equation (9) is evaluated on the safe side by about one digit.

The quality can be defined by arbitrarily combining the above six methods.

[0047]

According to the present invention, the buffer for the short-term cell discard rate at the time of a short-term overflow, the short-term cell discard rate for a call type, the duration of the overflow, and the duration of the underflow in which no overflow occurs in the case of a plurality of call types. The use of the less model provides a means that can be evaluated much more easily than the conventional method. Also, by providing simple evaluation means, it is possible to easily realize a traffic control method that guarantees a cell discard quality requirement suited to a user's viewpoint.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conceptual diagram of a traffic control device in a multi-call burst multiplex environment according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating traffic parameters in a multi-call burst multiplex environment according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a traffic control device according to an embodiment of the present invention.

FIG. 4 is a diagram showing an example of numerical values of quality in the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Link 20 Traffic control device 30 Quality evaluator 40 Judgment device

Continuation of the front page (56) References JP-A-4-111646 (JP, A) JP-A-4-280532 (JP, A) JP-A-5-191429 (JP, A) JP-A-5-167619 (JP) JP-A-3-284036 (JP, A) JP-A-3-58646 (JP, A) JP-A-2-171061 (JP, A) Yoshitaka TAKAHAS HI, “On the Pseudo-Conservation Law for Discrete” -Time Multi-Queue Systems with Priority Disciplines, "IEICE Technical Report, April 17, 1992, Vol. 92, no. 7, [switching system] SSE92-2, PP. 7-12 Hiroshi SUZUKI, et al. , "A Burst Trafic Control Control for ATM Networks," Conf. Rec. IEEE GLOBECOM '90, Dec. 1990, PP. 874-8 Hiroshi Suzuki and Shohei Sato, "Analysis of Short-Term Cell Loss Phenomena in ATM Networks", IEICE Technical Report, January 31, 1992, Vol. 91, No. 456, SSE91-144, PP. 43-48 San-Qi Li, "Study on Information Loss in Packet Voice Systems," IEEE Trans. on Comm. , Nov .; 1989, Vol. 37, No. 11, PP. 1192−1202 (58) Field surveyed (Int.Cl. ⁶ , DB name) H04L 12/28 H04L 12/56

Claims (5)

(57) [Claims] When a burst call of a plurality of call types is multiplexed on a link having a capacity C in an asynchronous transfer network, a short-term cell discard rate of a j-th call type during an overflow period in which cells are continuously discarded. In a burst traffic control system that evaluates Pov_j and regulates the input of burst traffic so that this value is equal to or less than a certain value, when a random variable representing a sum of arrival speeds of simultaneously arriving bursts on the link is R, R> C The average of the overflow rate Ov_j of the j-th call type among the total overflow rates RC in the period is obtained, and this is divided by the average of the arrival speed R_j of the j-th call type in the period where R> C. A short-term cell discard rate Pov_j based on the call type. 2. When multiplexing a plurality of types of burst calls on a link having a capacity C in an asynchronous transfer network, a cycle E {T} in which an overflow state in which cells are continuously discarded occurs is evaluated, and this is a constant value. In the burst traffic control method for restricting the input of burst traffic as described above, R is a random variable representing the sum of arrival rates of simultaneous arrival bursts on the link, and S is each state where R ≦ C.
When the transition probability of transition from the state S to the state of R> C is λs, an average of the transition probabilities λs is obtained for all the states S, and the period E {T} is evaluated by its reciprocal. Burst traffic control method. 3. When multiplexing burst calls of a plurality of types on a link having a capacity C in an asynchronous transfer network, the duration E {O} of an overflow state in which cells are continuously discarded is evaluated, and this is a constant value. In a burst traffic control method for restricting the input of burst traffic as follows, when a random variable representing the sum of the arrival speeds of bursts arriving simultaneously on the link is R, the probability that R is larger than C is P
3. The burst traffic control method according to claim 2, wherein said duration E {O} is evaluated by multiplying {R> C} by E {T} in claim 2. 4. When multiplexing a plurality of types of burst calls on a link having a capacity C in an asynchronous transfer network, the duration E {U} of an underflow state in which no cells are continuously discarded is evaluated, and this is a constant value. In the burst traffic control method for restricting the input of burst traffic as described above, when a random variable representing the sum of the arrival speeds of the simultaneously arriving bursts on the link is R, the probability that R is smaller than C is P
3. The burst traffic control method according to claim 2, wherein said duration time {U} is evaluated by multiplying {R≤C} by E {T} in claim 2. 5. When multiplexing a plurality of burst calls on a link having a capacity C in an asynchronous transfer network, the number of multiplexed burst calls, peak rate, average rate, burst duration, and burst interval are set to N, Peak, Avg, Ton. , The duration E {U} during which an underflow condition in which no cells are continuously discarded occurs is defined as the long-term cell discard rate Plong.
Equation {E} = (Ton / Plong) × Peak ² / (N
× AVG × (C-Peak)) or E {U} = (Ton / Plong) × Peak ² / C ² , and the burst traffic input is regulated so that this becomes a certain value or more. Traffic control method.