JP3088985B2 - Connection acceptance judgment 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 cell exchange.

[0002]

2. Description of the Related Art Unlike an STM (Synchronous Transfer Mode) exchange in which a band is assigned deterministically for each connection by designating a transmission slot position in a frame, in an ATM exchange, each connection transmits a cell at an arbitrary time. can do. 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 the ATM is transmitted to a VP (Virtual Path).
This is the output buffer of the exchange. As a simple cell transmission method, an algorithm in a FIFO (First in first out) output buffer is used. There is a cell read timing every one cell time, and at the read timing, if there is a cell in the buffer, the head cell of the buffer is read.

[0004] Peak rate, average rate, burstiness, peak duration, source type (eg, telephone, video), etc., are considered as possible traffic descriptors.

When the acceptability of a connection is determined using only the peak speed, the band use efficiency can be sufficiently increased when the burstiness of cell transmission from each connection is strong (the ratio between the average speed and the peak speed is large). 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).

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), based on the peak speed and average speed of the connection declared by the user, estimate the cell loss rate after accepting the connection, We have proposed a method to judge connection acceptance.

Saito's method is based on a peak rate R _i (maximum number of cells transmitted in γ cell time) and an 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 is estimated by the following equation.

[0008]

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

FIG. 7 shows a conventional connection acceptance determining device. The conventional connection acceptance determination device includes a connection connection request unit 1, a connection parameter unit under connection 3,
It comprises a cell loss rate estimating unit 4 and a connection acceptance determining unit 17. Connection parameter part 3 during connection
Has a memory for storing the peak speed and the average speed for each connection declared by the user.

FIG. 8 shows a conventional connection acceptance determination algorithm. When a connection request for a new connection occurs (S11), the peak speed R _{n + 1} , the average speed A _{n + 1 of} the new connection, and the parameters (peak speed, average speed) of the connected connection already accommodated in the VP. Is used to estimate the cell loss rate P using Equation 2 (S2). Assuming that CLR is a specified value of the cell loss rate, (S
3) If P <CLR, a connection is accepted (S7). Otherwise, the connection is not accepted (S8). In addition, a connection is accepted (S
7) When the connection is disconnected (S9), the connection parameter being connected is updated (S10).

[0011]

As described above, the conventional connection admission determining apparatus estimates the cell loss rate P when a connection connection request is made, and makes a connection admission judgment. However, when the number of accommodated connections is large, for example, when Expression 2 is used, it is necessary to perform convolution integration, so that the calculation time increases, and it takes time to determine connection acceptance. Therefore, it is difficult to make a connection acceptance determination in a short time.

FIG. 9 shows the concept of a conventional ATM switch for making a connection determination. Connection request is AT
When the connection arrives at the connection acceptance determining device 15 of the M exchange 20, the cell loss rate when a new connection is accepted and permitted is estimated, and the connection acceptance is determined according to the result. The determination result is transmitted to the transmission source of the connection connection request as a connection acceptance notification.

The present invention has been made in such a background, and an object of the present invention is to provide a connection admission determining apparatus capable of performing connection admission judgment in a short time.

[0014]

According to the present invention, an acceptable connection condition (parameter) is set in advance before an actual connection connection request, and when an actual connection connection request occurs, the actual connection condition is set. The most important feature is that connection acceptance determination is performed by comparing a connection connection request parameter with a preset acceptable connection parameter.

That is, the present invention provides a means for estimating a cell loss rate occurring with a new connection connection, and a means for accepting the new connection connection when the cell loss rate does not exceed a prescribed cell loss rate specified value. Is a connection acceptance determination device provided with:

Here, the feature of the present invention is that the virtual connection request is generated when there is no actual connection request, and the means for estimating the cell loss rate is a virtual connection request. A means for estimating and recording a cell loss rate every time a request is generated, wherein the means for receiving the connection request, when an actual connection request is generated, compares the estimated cell loss rate with a cell loss rate estimated for a recent virtual connection request. In this case, there is provided a means for omitting the estimation calculation of the cell loss rate for the actual connection request and making a determination as to whether or not the connection can be accepted.

The means for generating a virtual connection request may include a means for generating a virtual connection request in response to a change in an already set connection state, or may periodically include a virtual connection request. It may be configured to include a unit for generating a request.

The means for determining acceptability includes means for holding the condition of a currently acceptable connection request from a cell loss rate estimated and recorded for a virtual connection request without an actual connection request. Is desirable.

The condition can be a peak speed and an average speed of cell transfer, or a peak speed of cell transfer.

[0020]

Embodiments of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of a connection acceptance determining device according to an embodiment of the present invention.

The present invention provides a cell loss rate estimating section 4 which is means for estimating a cell loss rate occurring with a new connection connection, and a new cell loss rate estimating section 4 which is provided when the cell loss rate does not exceed a predetermined value. A connection reception determination device 10 including a connection reception determination unit 7 which is means for receiving a simple connection connection.

Here, a feature of the present invention is that a virtual connection connection request unit 2 which is a means for generating a virtual connection request when there is no actual connection request is provided. Each time this virtual connection request occurs, the cell loss rate is estimated and recorded, and the connection reception determination unit 7
When an actual connection request is generated, the estimation of the cell loss ratio for the actual connection request is omitted by comparing the estimated cell loss ratio with the estimated and recorded cell loss ratio for the latest virtual connection request, and the acceptability is determined. Where to do.

The virtual connection connection request unit 2 generates a virtual connection request in accordance with a change in the already set connection state, and periodically generates a virtual connection request.

The connection acceptance determining unit 7 is a means for retaining parameters which are conditions of connection requests that can be accepted at the present time from the cell loss rate estimated and recorded for a virtual connection request even if there is no actual connection request. It includes an acceptable connection parameter section 6.

This parameter can be the peak and average rate of cell transfer, or it can be the peak rate of cell transfer.

[0026]

(First Embodiment) FIG. 1 shows a connection acceptance determining apparatus according to a first embodiment of the present invention. The connection acceptance determination device 10 of the present invention includes a virtual connection connection request unit 2,
A connection parameter section 3, a cell loss rate estimating section 4, a virtual connection reception determining section 5, an acceptable connection parameter section 6, a connection connection request section 1, and a connection reception determining section 7 are provided.

FIG. 2 shows a connection acceptance determination algorithm according to the first embodiment of the present invention. In the conventional connection acceptance determination device 15, the estimation of the cell loss rate is performed only when there is a connection connection request. In the first embodiment of the present invention, unlike the actual connection connection request, a virtual connection connection request is generated (S1). The timing for generating a virtual connection request will be described in a second embodiment of the present invention.

For example, when the cell loss rate is estimated by the Saito method described in the conventional example (H. Saito, "Call Admission"
Control in an ATM Network Using Upper Bound of Cel
l Loss Probability, "IEEE Trans Commun, vol.40, no.9,
pp. 1512-1521, Sep. 1992.) As virtual connection parameters, a peak speed R ′ _{n + 1} and an average speed A ′ _{n + 1}
Set. Here, 'means a parameter of a virtual connection, and is distinguished from the parameter of Equation 3. Equation 3 is

[0029]

(Equation 2) Becomes Using Equation 4 instead of Equation 3, the cell loss rate P after accepting the virtual connection is estimated by Equation 2 (S2). If CLR is a specified value of the cell loss ratio, P <C
If it is LR (S3), the virtual connection can be accepted (S4). Otherwise, the connection is not accepted (S12).

When the virtual connection can be accepted (S4), the acceptable connection parameters are set in the acceptable connection parameter section 6 (S5).

FIG. 3 is a diagram for explaining the setting of the parameters of the acceptable connection. The horizontal axis indicates the peak speed, and the vertical axis indicates the average speed. The setting method is as follows. Parameters R ' _{n + 1} (set), A' already set in the acceptable connection parameters section
As in the _{n + 1} region, for example, figure (set) 3 (a), are set by using the memory. If (R ' _{n + 1} (se
If (t), A ' _{n + 1} (set)) is point A, the area is enlarged and set as shown in FIG. Also, (R ′
_{If n + 1} (set), A ′ _{n + 1} (set)) is point B, the area remains as it is. (R ′ _{n + 1} (set),
If A ′ _{n + 1} (set)) is a point C, the region is as shown in FIG.
The size is reduced and set as shown in FIG. Also, (R ′
_If ( _{n + 1} (set), A ′ _{n + 1} (set)) is point D, the area remains as it is.

If the virtual connection cannot be accepted (S12), the acceptable connection parameter values ( _{R'n + 1} (set), _{A'n + 1} (set)) can be set as large as possible. The parameters of the next virtual connection are set (S13). FIG. 4 is a diagram for explaining the setting of the parameters of the virtual connection.
In the next method of setting the parameters of the virtual connection, for example, one of the values of R ′ _{n + 1} and A ′ _{n + 1} is changed. The parameter of the virtual connection connection request to be changed is p (S21), and can be changed as shown in FIG. In the virtual connection reception determination (S22), when the reception is possible (S23), p ← p + p1 (5). Here, p1 is p1 <0, which is an increase in the parameter of the virtual connection. Further, when the reception is not possible (S24), p ← p + p2 (6). Here, p2 is p2 <0, which is a decrease in the parameter of the virtual connection. The newly set virtual connection parameters are used at the time of the next virtual connection connection request.

Returning to FIG. 2, when there is an actual connection connection request (S11), it is determined whether or not the actual connection connection parameter is within an acceptable connection parameter area (S6). At this time, the estimation of the cell loss rate is not performed. FIG. 5 is a diagram for explaining the reception determination. The horizontal axis indicates the peak speed, and the vertical axis indicates the average speed. For example, as shown in FIG. 5, if the actual connection connection parameters (R _{n + 1} , A _{n + 1} ) are at point X, the actual connection can be accepted. If (R _{n + 1} , A _{n + 1} ) is the point Y, it is determined that an actual connection cannot be accepted. When an actual new connection is accepted (S7), the parameters of the currently connected connection are updated (S10).

As described above, in the first embodiment of the present invention, a connection request for a virtual connection is generated in advance, the cell loss rate after accepting the virtual connection is estimated, Is set in advance before the actual connection connection request, at the time of the actual connection request, it is sufficient to determine whether the actual connection connection parameter is within the acceptable connection parameter area, There is no need to calculate the cell loss rate. Therefore, connection acceptance determination can be performed in a short time.

FIG. 6 shows the concept of the ATM switch 20 for performing connection determination according to the first embodiment of the present invention. When the connection connection request arrives at the connection reception determining device 10 of the ATM exchange 20, the connection reception determination is performed. The connection reception determination device 10 has already performed the cell loss rate estimation according to the virtual connection connection request, and the virtual connection reception determination is performed. Is being done. At this time, a parameter for connection acceptance determination has been set, and connection acceptance determination is promptly performed by referring to this parameter. The determination result is transmitted to the source of the connection request.

(Second Embodiment) In a second embodiment of the present invention, the timing of a virtual connection connection request will be described.
The virtual connection connection request occurs when one of the following conditions is satisfied. -When the connection state of the connection changes, that is, when a new connection is connected, or when the currently connected connection is disconnected,-When a certain period of time has elapsed since the last virtual connection connection request, a virtual connection In order to periodically generate a connection request, the connection acceptance determination device has a timer.

Therefore, when the connection state of the connection changes or a virtual connection connection request is generated periodically, the area of the connection parameters that can be accepted is updated, and before the actual connection connection request, Can be set in advance.

(Third Embodiment) In order to simplify the setting of the connection acceptable area from the first embodiment of the present invention, the average speed A 'of the parameter of the virtual connection connection request is set.
_Assuming that _{n + 1} is the same as the peak speed _{R'n + 1} , it is also possible to set _{A'n + 1} = _{R'n + 1} (7). In the actual connection acceptance determination, the comparison between the actual connection connection request parameter and the connection acceptable parameter is R _{n + 1}
The parameters may be set as R _{n + 1} and R ′ _{n + 1} , respectively.

Even if such a comparison is made only for the parameters of the peak speed, the specified value of the cell loss rate of the connection can be guaranteed.

In the case of only the peak speed, there is no need to have a table or the like for setting an area in the memory. For example, one real numerical value may be set in the memory.

Therefore, it is possible to simplify the parameters of the virtual connection connection request, the setting of the connection receivable area, and the determination of the acceptance of the actual connection.

(Fourth Embodiment) In the first embodiment of the present invention, the cell loss rate P
_{Although clr} was estimated, Aida et al. described the literature [M. Aida and T. Kubo, "Efficient Cel"
l-Loss Ratio Estimation for Real-Time CACDecisio
n, "IEICE Trans.Commun., vol.E79-B, no.2, pp.108-115, F
eb. 1996.], and Murase et al.
urase, H.Suzuki, S.Sato and T.Takeuchi, "A Call Admis
sion Control Estimate, "IEEE Journal of Selected Ar
eas in Communications, vol. 9, no. 9, pp. 1461-1470, Apr.
1991.]]. 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.

Here, Aida's method will be described. The equation for estimating the cell loss rate is given by the following equation.

[0044]

(Equation 3) However, Equation 9 can be used when C ₃ > 0, and when C ₃ ≦ 0, another equation is used. This is described in the literature [M. Aida and T. Kubo, "Efficient Cell-
Loss Ratio Estimation for Real-Time CAC Decision, "
IEICE Trans.Commun., Vol.E79-B, no.2, pp.108-115, Feb.
1996.]].

Further, the user declares only the peak speed P _{n + 1} as a traffic descriptor, and declares the average speed A _{n + 1}
May not be declared. In this case, the actual connection acceptance determination is made using only the peak speed as a parameter, as in the third embodiment of the present invention, using A _{n + 1} = R _{n + 1} in Expression 2.

The average speed A of the currently connected connection
_i can be determined on the network side by periodic measurement using the technique disclosed in Japanese Patent Application No. 9-231317 (not disclosed at the time of filing the present application). According to the disclosed technology, the average speed A _i can be obtained by measuring the number of cells arriving at the measured connection.

That is, the average speed is γ at time t.
The average rate within the cell time is A _i (t), the measurement period of the number of cells arriving at the measured connection is T, the measurement interval is ΔT, and the number of cells arriving within the T cell time at time t is B _i (t). And the smoothing coefficient is α, it can be obtained as A _i (t) = (1−α) A _i (t−ΔT) + α (γ / T) B _i (t).

[0048]

As described above, according to the present invention,
Generate a connection request for a virtual connection in advance, estimate the cell loss rate after accepting the virtual connection, and set in advance the area of the acceptable connection parameters before the actual connection connection request. Therefore, when an actual connection request is made, it is sufficient to determine whether or not the actual connection connection parameter is within an acceptable connection parameter area, and there is no need to calculate the cell loss rate. Therefore, connection acceptance determination can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a block diagram of a connection acceptance determination device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a connection acceptance determination algorithm according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining setting of parameters of an acceptable connection.

FIG. 4 is a view for explaining setting of parameters of a virtual connection;

FIG. 5 is a diagram for explaining a reception determination.

FIG. 6 is a diagram illustrating an example of a connection determination A according to the first embodiment of the present invention.
The figure which shows the concept of a TM exchange.

FIG. 7 is a diagram showing a conventional connection acceptance determination device.

FIG. 8 is a diagram showing a conventional connection acceptance determination algorithm.

FIG. 9 is a diagram showing the concept of a conventional ATM switch for performing connection determination.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Connection connection request part 2 Virtual connection connection request part 3 Connection parameter part under connection 4 Cell loss rate estimation part 5 Virtual connection reception judgment part 6 Acceptable connection parameter part 7, 17 Connection reception judgment part 10, 15 Connection reception judgment device 20 ATM switch

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-237264 (JP, A) JP-A-7-303107 (JP, A) JP-A-9-130386 (JP, A) IEICE Technology Research Report SS E97-160 (December 19, 1997) 1998 IEICE General Conference B-6-6 (March 6, 1998) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) H04L 12/28 H04L 12/56

Claims (6)

(57) [Claims] 1. Means for estimating a cell loss rate generated due to a new connection connection, and means for receiving the new connection connection request when the cell loss rate does not exceed a prescribed cell loss rate specified value. The connection acceptance determination device further comprises means for generating a virtual connection request when there is no actual connection request, and the means for estimating the cell loss rate comprises: The means for estimating and recording, the means for receiving the new connection connection request, when an actual connection request occurs, by comparing with the cell loss rate estimated and recorded for a recent virtual connection request, A connection admission judgment device comprising means for omitting an estimation calculation of a cell loss rate for an actual connection request and judging the admissibility thereof. 2. The connection acceptance determination device according to claim 1, wherein said means for generating a virtual connection request includes means for generating a virtual connection request in response to a change in a previously set connection state. 3. The connection acceptance determination device according to claim 1, wherein said means for generating a virtual connection request includes means for periodically generating a virtual connection request. 4. The means for performing acceptability determination includes means for holding a condition of a currently acceptable connection request from a cell loss rate estimated and recorded for a virtual connection request without an actual connection request. The connection acceptance determination device according to claim 1 including: 5. The connection admission judgment device according to claim 4, wherein said condition is a peak speed and an average speed of cell transfer. 6. The connection admission judgment device according to claim 4, wherein said condition is a peak speed of cell transfer.