JPH11112516A - ATM quality estimation method, ATM multi-class call admission control method and apparatus - Google Patents

Abstract

(57) [Summary] [Problem] A call admission control capable of dramatically improving the effect of using a transmission line without impairing features of a conventional call admission control method such as real-time processing performance and support of a plurality of service categories. To provide a method and apparatus. SOLUTION: The present invention receives a connection request of a call belonging to any of a plurality of service categories of which priority is set, and determines the received connection request based on a service category requested by the connection request. In the case where it is assumed that the received connection request is accepted, the quality of the service category requested by the connection request is evaluated, and the quality of another service category is evaluated for each service category. Based on the result of (1), it is determined whether or not the received connection request can be accepted, and for the connection request call determined to be acceptable, the cell of the call is stored in the buffer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a call admission control method and apparatus for estimating a cell loss rate based on a traffic report parameter from a user in an ATM network and determining whether or not to accept a call.

[0002]

2. Description of the Related Art In an ATM network, characteristics (communication speed,
Several service categories are prepared corresponding to traffic having different service qualities). For this reason,
A call admission control method based on the existence of a plurality of service categories is required.

A call admission control method for judging whether a call can be accepted based on a traffic parameter declared by a user corresponds to a plurality of service categories, and uses only a peak rate and an average rate as traffic parameters to obtain a predetermined communication quality. A technique for performing real-time processing so as to satisfy a request is known. The communication quality requirement is determined by, for example, a cell loss rate related to a transmission line (VP) that accommodates a call. This method is performed for each VP, and is performed in the call admission control unit 1 shown in FIG. 5 under the configuration shown in FIG.
This is realized by the processing flow shown in FIG. 10, and the call acceptance processing is performed within a fixed time regardless of the number of calls or traffic conditions. The details of this method will be described below.

[0004] As a plurality of service categories, CBR, R
ealtime VBR (RtVBR), Non-re
It is assumed that an ultimate VBR (NrtVBR) and a best effort class (ABR, UBR) are used. Also,
The declared value of CBR and best effort class is only the peak cell rate. On the other hand, RtVBR and NrtVBR
Are the peak cell rate and the average cell rate.

The cells input from the call sources belonging to these service categories are input to buffers prepared for each service category in the ATM exchange (FIG. 1).
reference). The priority order is CBR,
RtVBR, NrtVBR, best effort class. A cell that exists in a buffer is transferred only when no cell exists in a buffer with a higher priority than that buffer.

[0006] 1. In order to process call acceptance in real time, the number N of repetitive calculations allowed for the VP cell loss rate estimation processing is determined in advance. 2. With respect to the VP, the identifier i (i = 1, 2,..., (The number of set connections + 1)) is assigned to all the users who have already set up a connection to the VP and who have newly made a call setting request. Give. 3. A user i who newly sets up a call sets a desired service category (CBR, RtVB) when requesting call setting.
R, NrtVBR, Best Effort Class (ABR,
UBR)) and the peak cell rate r _i (1 / sec)
And the average cell rate a _i (1 / sec, where the desired service category is RtVBR or NrtVB
(Valid in the case of R) to the call admission control unit 1 (see FIG. 5). 4. The service category check unit 1a (see FIG. 6)
Service category (CBR, Rt) declared by the user
Based on VBR, NrtVBR, best effort class), the call that has received the reception request is classified, and the call is passed to the corresponding call reception processing unit. 5. Each of the call reception processing units 1b to 1e executes a reception process described later, and notifies whether the call can be received. 6. If it is determined that all VPs that accommodate the call can be accepted, acceptance of the call is permitted.

Next, the above 4. Processing (each call reception processing unit 1)
b to 1e) will be described individually. (1) Processing of CBR call reception processing unit 1b The CBR call reception processing unit 1b executes the following processing (see FIG. 7).

[0008] 1. (Sum of peak cell rates of CBR calls that have been accepted) + (Peak cell rate of CBR calls subject to acceptance determination) are calculated (step Sb1). 2. A band obtained by excluding the band (that is, the calculation result of 1.) from all VP bands is calculated, and the calculation result is set as a remaining band Z (step Sb2). 3. If the remaining band Z is positive, the process proceeds to step SB4. Otherwise, the reception failure is notified and the process is terminated (step Sb3).

4. Accepted RtVBR call, NrtVB
Assuming that only the R call is accommodated in the remaining band Z, Nr
The cell loss rate B _nrt of only tVBR is estimated (step Sb4). The procedure is as follows. -For accepted RtVBR calls and NrtVBR calls,
Based on the peak cell rate r _i and the average cell rate a _i of these calls, the following quantities are calculated. _{R i = INT (γ · L} · r i / C) A i = γ · L · a i / C where, INT (x) is the smallest integer greater than or equal to x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). γ is a constant (cell) that depends on the output buffer capacity K of the multiplexer.・ Next, calculate the following value Γ. Γ = γ · Z / C • Using the above R _i , A _i , and で, RtVBR
The cell loss rate estimated value * B for the mixed traffic of the call and the NrtVBR call is calculated as follows.

(Equation 9) here

(Equation 10) It is. Here, Σ ^r and Σ ⁿ are the accepted RtV
A set of BR calls and NrtVBR calls. Also, D = max (C ₃ , _CL ), and

[Equation 11] It is. -The estimated cell loss rate * B is RtVBR and NrtV
It is a cell loss rate for BR mixed traffic. Therefore, in order to estimate the cell loss rate B _nrt of only NrtVBR, the following calculation is performed on the assumption that all the lost cells are generated from NrtVBR cells.

(Equation 12)

[0010] 5. Cell loss rate B of NrtVBR only
_{If nrt} is equal to or smaller than the specified value, the process proceeds to step Sb6. Otherwise, notification of rejection is given, and the process ends (step Sb5).

6. Only accepted already rtVBR call, assuming that it has received in the remaining bandwidth Z, to estimate cell loss probability B _rt only rtVBR (step Sb6). The procedure is as follows. · For the accepted all RtVBR calls, based on these peak cell rate of call r _i and an average cell rate a _i, compute the following quantities. _{R i = INT (γ · L} · r i / C) A i = γ · L · a i / C where, INT (x) is the smallest integer greater than or equal to x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). γ is a constant (cell) that depends on the output buffer capacity K of the multiplexer.・ Next, calculate the following value Г. Г = γ · Z / C • By applying the above R _i , A _i , and に to the call admission control method corresponding to a single class, the cell loss rate estimated value * B is calculated by the following equation.

(Equation 13) here,

[Equation 14] It is. Also, D = max (C ₃ , _CL ), and

(Equation 15) It is. · The cell loss ratio estimate * B, and cell loss ratio B _rt only rtVBR. B _rt = * B

7. Cell loss rate B _{rt of} only RtVBR
Is less than or equal to the specified value, the reception of the CBR call requested to be received is notified. If not, it notifies the reception impossibility (step Sb7). 8. When it is determined that all the VPs through which the call passes can be accepted, the acceptance of the call is permitted.

(2) Processing of RtVBR call reception processing section 1c The RtVBR call reception processing section 1c executes the following processing (see FIG. 8). 1. A band corresponding to the total sum of the peak cell rates of the accepted CBR calls is calculated by removing the band from all the VP bands, and the calculation result is set as a remaining band Z (step Sc1).

2. Accepted RtVBR call, NrtVB
R call and RtVBR call for which reception
NrtVBR only cell, assuming housed in band Z
Loss rate B_nrt Is estimated (step Sc2). The procedure
Is as follows. -Accepted RtVBR calls, NrtVBR calls,
For RtVBR calls that have been requested to attach,
Kosell rate r_i And average cell rate a _i Based on
And calculate the following quantities: R_i = INT (γ ・ L ・ r_i / C) A_i ＝ γ ・ L ・ a_i / C where INT (x) is the smallest integer not less than x.
You. L is a cell length (bit / cell). C is the VP capacity
(Transmission rate bit / cell). γ is the output of the multiplexer
This is a constant (cell) depending on the buffer capacity K.・ Next, calculate the following value Г. Г = γ · Z / C ・ R above_i , A_i , Г, and RtVB
Cell loss for mixed traffic of R and NrtVBR calls
The estimated loss rate * B is calculated as follows.

(Equation 16) here

[Equation 17] It is. Here, Σ ^{r *} is a union set of the accepted RtVBR call and the RtVBR call for which the acceptance request was made { ^{r *} = { ^r } RtVBR call for which the acceptance request was made}. Also, D = max (C ₃ , _CL ), and

(Equation 18) It is. -The estimated cell loss rate * B is RtVBR and NrtV
It is a cell loss rate for BR mixed traffic. Therefore, in order to estimate the cell loss rate B _nrt of only NrtVBR, the following calculation is performed on the assumption that all the lost cells are generated from NrtVBR cells.

[Equation 19]

3. Cell loss rate B of NrtVBR only
_{If nrt} is equal to or _smaller than the specified value, the process proceeds to step Sc4. Otherwise, the reception failure is notified, and the process ends (step Sc3).

4. Accepted already rtVBR call, and the rtVBR call for which the admission request, assuming accommodated in the residual band Z, to estimate cell loss probability B _rt only rtVBR (step Sc4). The procedure is as follows. - the accepted all RtVBR call, and, for RtVBR for which the admission request, on the basis of these peaks call cell rate r _i and the average cell rate a _i, compute the following quantities. _{R i = INT (γ · L} · r i / C) A i = γ · L · a i / C where, INT (x) is the smallest integer greater than or equal to x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). γ is a constant (cell) that depends on the output buffer capacity K of the multiplexer.・ Next, calculate the following value Г. Г = γ · Z / C • By applying the above R _i , A _i , and に to the call admission control method corresponding to a single class, the cell loss rate estimated value * B is calculated by the following equation.

(Equation 20) here,

(Equation 21) It is. Also, D = max (C ₃ , _CL ), and

(Equation 22) It is. · The cell loss ratio estimate * B, and cell loss ratio B _rt only rtVBR. B _rt = * B

5. If the cell loss rate of only the RtVBR is equal to or less than a specified value, the mobile station notifies the reception of the RtVBR call requested to be accepted. If not, a notification of rejection is given (step Sc5). 6. When it is determined that all VPs that can accommodate the call can be accepted, acceptance of the call is permitted.

(3) Process of NrtVBR call reception processing unit 1d The NrtVBR call reception processing unit 1d executes the following processing (see FIG. 9). 1. A band corresponding to the total sum of the peak cell rates of the accepted CBR calls is calculated by excluding the band from all the VP bands, and the calculation result is set as a remaining band Z (step Sd1).

2. Accepted RtVBR call, NrtVB
The R call and the NrtVBR call for which the reception request
Assuming that it is accommodated in the remaining band Z, only the NrtVBR
Loss rate B_nrt Is estimated (step Sd2). That hand
The order is as follows. -Accepted RtVBR calls, NrtVBR calls,
For NrtVBR calls that have been requested,
Peak cell rate r_i , And cell rate a _i Based on
And calculate the following quantities: R_i = INT (γ ・ L ・ r_i / C) A_i ＝ γ ・ L ・ a_i / C where INT (x) is the smallest integer not less than x.
You. L is a cell length (bit / cell). C is the VP capacity
(Transmission rate bit / cell). γ is the output of the multiplexer
This is a constant (cell) depending on the buffer capacity K.・ Next, calculate the following value Г. Г = γ · Z / C ・ R above_i , A_i , Г, and RtVB
Cell loss for mixed traffic of R and NrtVBR calls
The estimated loss rate * B is calculated as follows.

(Equation 23) here

(Equation 24) It is. Here, ^{{n *} is the union set of the accepted NrtVBR call and the NrtVBR call for which the acceptance request was made, { ^{n *} = ^{{ n}} }.
{NrtVBR call for which reception was requested}. Also, D = max (C ₃ , _CL ), and

(Equation 25) It is. -The estimated cell loss rate * B is RtVBR and NrtV
It is a cell loss rate for BR mixed traffic. Therefore, in order to estimate the cell loss rate B _nrt of only NrtVBR, the following calculation is performed on the assumption that all the lost cells are generated from NrtVBR cells.

(Equation 26)

3. Cell loss rate B of NrtVBR only
_{If nrt} is equal to or less than a specified value, NrtV for which a reception request has been made
Notify that the BR call can be accepted. If not, a notification of rejection is given (step Sd3). 4. When it is determined that all VPs that can accommodate the call can be accepted, acceptance of the call is permitted.

(4) Processing of Best Effort Class Call Reception Processing Unit 1e The best effort class call reception processing unit 1e executes the following processing (see FIG. 10). 1. If the peak cell rate of the best-effort class call for which a reception request has been made is equal to or less than the total VP capacity, notification is made that the reception of the requested best-effort class call is acceptable. If not, a notification of rejection is given (step Se1). 2. If it is determined that all VPs that can accommodate the call can be accepted, the acceptance of the call is permitted.

With the above procedure, call admission control for a plurality of service categories is executed without adversely affecting the quality of other service categories. Further, the processing for the reception control is completed within a predetermined time. The prior art described above does not use a convolution operation that depends on the number of call types and the number of connections. Therefore, the calculation time is determined only by the parameter N of the predetermined number of repetition calculations, and the cell loss rate estimated value * B can be obtained with a calculation amount independent of the number of VCs and the number of types of VCs. The call admission control that satisfies the communication quality requirement determined by the rate is realized in real time.

[0023]

However, the cell loss rate estimating method used in the above prior art is based only on the peak rate and average rate of traffic, and is effective when the output buffer capacity of the exchange is small. However, when it is large, there is a problem that the traffic multiplexing effect of the buffer is not properly reflected in the cell loss rate estimation. In recent years, in response to a situation in which data communication services using an ATM network are being actively discussed, the output buffer capacity of the exchange tends to increase, and call admission control based on only the peak rate and the average rate is not sufficient. Absent. Therefore, based on the cell loss rate estimating method for appropriately estimating the multiplexing effect depending on the output buffer capacity of the exchange using information on the maximum burst size in addition to the peak rate and average rate of the traffic, There has been a demand for a call admission control method capable of real-time processing corresponding to a service category.

[0024] An object of the present invention is to solve the above-mentioned problems by supporting a plurality of service categories in the conventional call admission control method and without impairing the features of real-time processing, in addition to the peak traffic rate and the average traffic rate. It is an object of the present invention to provide a call admission control method and apparatus for providing an appropriate multiplexing effect depending on the output buffer capacity of a switch by using information on a burst size.

[0025]

The present invention provides: a peak rate for each connection of a general VBR class;
Use the average rate, maximum burst size information,
A technique for estimating the cell loss rate in real time using information on the output buffer capacity of the exchange; and- setting a priority between the output buffers of the exchanges prepared for each service category, and preparing for each service category. And a technique for real-time estimation of the quality of only a specific VBR service category by assuming that the output buffer of the exchange has a fixed capacity. According to the present invention, for a plurality of service categories, whether or not a call belonging to the service category can be accepted depends on the quality of its own service category and whether the quality of other service categories is affected depends on the output buffer capacity of the exchange. The estimated multiplexing effect is also taken into consideration, and based on the estimation, it is determined whether the call can be accepted. In addition, the process of the determination is independent of the number of calls requested to be accepted and the output buffer capacity of the exchange,
It ends in a certain time. As a result, it is possible to appropriately determine the multiplexing effect and to control the admission of calls that can be processed in real time in correspondence with a plurality of service categories.

[0026]

An embodiment of the present invention will be described below with reference to the drawings. §1. Overview In the present embodiment, CBR, R
ealtime VBR (RtVBR), Non-re
It is assumed that an ultimate VBR (NrtVBR) and a best effort class (ABR, UBR) are used. Of course, the types of service categories to which the present invention can be applied are not limited to the present embodiment, and can be easily extended to other variations. The declared values of the CBR and the best effort class are only the peak cell rate. On the other hand, RtV
The declared values of BR and NrtVBR are the peak cell rate, average cell rate, and maximum burst size.

Cells input from the call sources belonging to these service categories are input to buffers prepared for each service category in the ATM exchange (FIG. 1).
reference). It is assumed that each buffer has a predetermined fixed capacity. Note that the configuration of the buffer is not limited to FIG. 1 and is designed according to the type of service category. The priority of cell transfer is set in each buffer. The priorities are, for example, CBR, Rt in descending order of priority.
VBR, NrtVBR, and best effort class. A cell that exists in a buffer is transferred only when no cell exists in a buffer with a higher priority than that buffer.

According to the present invention, call admission control for a plurality of service categories is executed in real time while appropriately considering the multiplexing effect depending on the output buffer capacity of the exchange. The present invention is configured based on the following technology. 1. A buffer (FIG. 1) having a fixed capacity for each service category is prepared in the ATM exchange. Then, the priority of cell transfer is set between the buffers. Then, cell transfer of a buffer belonging to a certain service category is executed only when no cell exists in all buffers having a higher priority than the buffer. Thus, it is possible to prevent the behavior of each service category from affecting the quality of the service category having a higher priority than the service category. As a result, the quality estimation process of the service category can be executed only by considering only the influence on the quality of the service category having a lower priority than the service category.

2. Real-time estimation of the general cell loss rate * B of the VBR class with respect to the output buffer capacity of the exchange using three quantities of the peak cell rate, the average cell rate, and the maximum burst size as the traffic parameters for each VBR call. Cell loss rate estimation technology. Each VB
For the R call i, the following amounts are calculated and stored based on the peak cell rate r _i , the average cell rate a _i , and the maximum burst size B _i .

[Equation 27] Here, INT (x) is a minimum integer equal to or larger than x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). Г is the VB of the multiplexer
When the output buffer capacity for R is K (cell), it is determined by Г = K + 1. Using the above P _i , S _i , α _i , Г, the cell loss rate estimated value * B is calculated by the following equation.

[Equation 28] Here, N is a positive integer of 4 or more (recommended value N = 10),

(Equation 29) It is. Here, Σ is a set of VBR calls. Also, D = max (C ₃ , _CL ), and

[Equation 30] It is. As a result, it is possible to estimate the cell loss rate within a fixed time which does not depend on the number of connections and the output buffer capacity of the switch, taking into account the multiplexing effect depending on the output buffer capacity of the switch.

3. The quality estimation processing for each service category is performed using the above-described real-time cell loss rate estimation technology. This makes it possible to execute the quality estimation process for each service category in real time. Specifically, this technique estimates a cell loss rate for traffic multiplexed with calls of a plurality of service categories in real time using the cell loss rate estimation method described in the above item 2, and then all loss cells are estimated. Is assumed to belong to the low priority service category, and the cell loss rate of the low priority service category is estimated.

4. When a request for setting a call belonging to a certain service category is received, the quality of the service category and a lower service category in the case where it is assumed that the call for which the setting request has been received are determined by the above-mentioned items 2 and 3.
The estimation request is estimated for each service category using the quality estimation technology for each service category described in the section, and the setting request is accepted only when all the quality estimation values satisfy the specified value. As a result, the VP of the already set connection
It is possible to perform call admission control for a plurality of service categories after appropriately considering the effect on quality for each multiplexing effect depending on the output buffer capacity of the exchange.

§2. Embodiment Hereinafter, an ATM call admission control method according to an embodiment of the present invention will be described. In the present embodiment, a call admission control unit 2 is used instead of the call admission control unit 1 in the ATM network shown in FIG. FIG. 2 is a block diagram illustrating a configuration example of the call admission control unit 2. The call admission control unit 2 adds a function of supporting a maximum burst length of a connection to the call admission control unit 1. This ATM call admission control method is performed by the call admission control unit 2 for each VP.

In such a configuration, the call admission control method according to the present embodiment is performed in the following procedure. 1. In order to process the call reception in real time, the number of repetition calculations N allowed for the VP cell loss rate estimation processing is determined in advance (recommended value N = 10). 2. With respect to the VP, an identifier i (i = 1, 2,..., The number of set connections + 1) is assigned to all users who have already set up a connection to the VP and who have newly requested a call setup. .

3. A user i who newly sets up a call sets a desired service category (CB) when requesting call setting.
R, rtVBR, nrtVBR, a best effort class), and the peak cell rate r _i (1 / sec), the average cell rate a _i (1 / sec, however, the service category of the desired, effective when rtVBR or nrtVBR) And the maximum burst size B _i (cell, where the desired service category is RtVBR or Nr
(valid for tVBR) to the call admission control unit 2.

4. Service category check section C (FIG. 2)
Reference) is the service category (C) declared by the user.
Based on the BR, RtVBR, NrtVBR, best-effort class), the call that has received the reception request is classified, and the call is passed to the corresponding call reception processing unit A or B. 5. Each call reception processing unit executes a reception process described later, and notifies whether reception is possible. 6. If it is determined that all VPs that accommodate the call can be accepted, acceptance of the call is permitted.

Next, 4. (Reception processing in the call reception processing units A and B) will be individually described. (1) Processing of Call Acceptance Processing Unit A in CBR Call Acceptance Processing In the case of CBR call acceptance, the call acceptance processing unit A executes the following processing (see FIG. 3). 1. (Total sum of peak cell rates of accepted CBR calls)
+ (Peak cell rate of CBR call subject to acceptance judgment)
Is calculated (step A1). 2. When the band (that is, the calculation result of the above 1) is all V
If the capacity is equal to or less than the P capacity, the process proceeds to step A3.
2).

3. Accepted CBR call and RtVB
And R call, a CBR call to be accepted determination target, assuming accommodated in VP, to estimate cell loss probability B _rt only rtVBR (step A3). The procedure is as follows. For all accepted RtVBR calls, calculate and hold the following quantities when accepting each call, based on the peak cell rate, average cell rate, and maximum burst size of these calls:

(Equation 31) Here, INT (x) is a minimum integer equal to or larger than x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). Г _r is the multiplexing device R
When the output buffer capacity for tVBR is K _r (cell), it is determined by Г _r = K _r +1. Using the above P _i , S _i , α _i , Г _r ,
The cell loss rate estimated value * B is calculated.

(Equation 32) Here, Σ ^{c *} is the CBR call that has been accepted and the C that has received the acceptance request.
The union set of BR calls, Σ ^r is the set of accepted RtVBR calls,

[Equation 33] It is. Also, D = max (C ₃ , _CL ), and

(Equation 34) It is. The above mentioned cell loss ratio estimate * from B, and calculated as follows cell loss ratio B _rt only rtVBR.

(Equation 35)

4. Cell loss rate B _{rt of} only RtVBR
If the value is equal to or less than the specified value, the process proceeds to step A5.
4). 5. Accepted CBR call, RtVBR call, and Nrt
Assuming that the VBR call has been accommodated in the VP, NrtVBR
Only the cell loss rate B _nrt is estimated (step A5).
The procedure is as follows. For all the accepted RtVBR calls and NrtVBR calls, the following amounts are calculated and held when each call is accepted based on the peak cell rate, average cell rate, and maximum burst size of these calls. .

[Equation 36] Here, INT (x) is a minimum integer equal to or larger than x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). Г _n is the N of the multiplexer
When the output buffer capacity of the rtVBR is K _n (cell), it is determined by Г _n = K _n +1. Using the above P _i , S _i , α _i , Г _n ,
The cell loss rate estimated value * B is calculated.

(37) Here, Σ ^{c *} is the CBR call that has been accepted and the C that has received the acceptance request.
Assume that a union set of BR calls, Σ ^r is a set of accepted RtVBR calls, Σ ⁿ is a set of accepted NrtVBR calls,

(38) It is. Also, D = max (C ₃ , _CL ), and

[Equation 39] It is. From the cell loss rate estimated value * B, the cell loss rate B _nrt of only NrtVBR is calculated as follows.

(Equation 40)

6. Cell loss rate B of NrtVBR only
_{If nrt} is equal to or less than the specified value, the acceptance of the CBR call for which acceptance is requested to the VP is permitted. If not, a notice of non-acceptance is given and the process is terminated (step A6). 7. When it is determined that all the VPs through which the call passes can be accepted, the acceptance of the call is permitted.

(2) Processing of Call Acceptance Processing Unit A in RtVBR Call Acceptance Processing In the case of RtVBR call acceptance, the call acceptance processing unit A executes the following processing (see FIG. 3). 1. Accepted already CBR call, rtVBR call, and the rtVBR call for which the admission request, assuming accommodated in VP, to estimate cell loss probability B _rt only rtVBR (step A3). The procedure is as follows. For all accepted RtVBR calls and RtVBR calls for which acceptance has been requested, the following amounts are accepted when each call is accepted, based on the peak cell rate, average cell rate, and maximum burst size of these calls: Calculate and keep.

[Equation 41] Here, INT (x) is a minimum integer equal to or larger than x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). Г _r is the multiplexing device R
When the output buffer capacity for tVBR is K _r (cell), it is determined by Г _r = K _r +1. Using the above P _i , S _i , α _i , Г _r ,
The cell loss rate estimated value * B is calculated.

(Equation 42) here,

[Equation 43] It is. Where Σ ^c is the set of accepted CBR calls, Σ ^{r *}
Is the RtVBR call that has been accepted and the RtV that has been accepted
Merged set of BR calls Σ ^{r *} = Σ ^{r Ｒ} Rt requested to accept
VBR call. Also, D = max (C ₃ , _CL ), and

[Equation 44] It is. The above mentioned cell loss ratio estimate * from B, and calculated as follows cell loss ratio B _rt only rtVBR.

[Equation 45]

2. Cell loss rate B _{rt of} only RtVBR
If the value is equal to or less than the specified value, the process proceeds to step A5.
4). 3. Accepted CBR call, RtVBR call, NrtVBR
Assuming that the call and the RtVBR call for which the admission request was received are accommodated in the VP, the cell loss rate B of only the NrtVBR is assumed.
Estimate _nrt (step A5). The procedure is as follows. For all accepted RtVBR calls, NrtVBR calls, and RtVBR calls for which acceptance has been requested, based on the peak cell rate, average cell rate, and maximum burst size of these calls, Calculate the amount of and keep it.

[Equation 46] Here, INT (x) is a minimum integer equal to or larger than x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). Г _n is the N of the multiplexer
When the output buffer capacity of the rtVBR is K _n (cell), it is determined by Г _n = K _n +1. Using the above P _i , S _i , α _i , Г _n ,
The cell loss rate estimated value * B is calculated.

[Equation 47] Here, Σ ^c is a set of accepted CBR calls, Σ ^{r *} is a merged set of RtVBR calls that have been accepted and RtVBR calls that have been accepted, and Σ ⁿ is a set of accepted NrtVBR calls.

[Equation 48] It is. Also, D = max (C ₃ , _CL ), and

[Equation 49] It is. From the cell loss rate estimated value * B, the cell loss rate B _nrt of only NrtVBR is calculated as follows.

[Equation 50]

4. Cell loss rate B of NrtVBR only
_{If nrt} is equal to or less than the specified value, the reception of the VBR call requested to be accepted to the VP is permitted. If not, a notice of non-acceptance is given and the process is terminated (step A6). 5. When it is determined that all the VPs through which the call passes can be accepted, the acceptance of the call is permitted.

(3) Process of Call Acceptance Processing Unit A in NrtVBR Call Acceptance Process In the case of NrtVBR call acceptance, the call acceptance processing unit A executes the following process (see FIG. 3). 1. Accepted CBR call, RtVBR call, NrtVBR
Assuming that the call and the NrtVBR call for which the admission request has been received are accommodated in the VP, the cell loss rate B of only the NrtVBR
Estimate _nrt (step A5). The procedure is as follows. For all accepted RtVBR calls, NrtVBR calls, and NrtVBR calls for which acceptance has been requested, based on the peak cell rate, average cell rate, and maximum burst size of these calls, Calculate the amount of and keep it.

(Equation 51) Here, INT (x) is a minimum integer equal to or larger than x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). Г _n is the N of the multiplexer
When the output buffer capacity of the rtVBR is K _n (cell), it is determined by Г _n = K _n +1. Using the above P _i , S _i , α _i , Г _n ,
The cell loss rate estimated value * B is calculated.

(Equation 52) Here, Σ ^c is a set of accepted CBR calls, Σ ^r is a set of accepted RtVBR calls,

(Equation 53) It is. Here, ^{{n *} is the union set of the accepted NrtVBR call and the NrtVBR call for which the acceptance request was made, { ^{n *} = ^{{ n}} }.
{NrtVBR call for which reception was requested}. Also, D = max (C ₃ , _CL ), and

(Equation 54) It is. From the cell loss rate estimated value * B, the cell loss rate B _nrt of only NrtVBR is calculated as follows.

[Equation 55]

2. Cell loss rate B of NrtVBR only
_{If nrt} is equal to or less than a specified value, NrtV for which a reception request was made
Notify that the BR call can be accepted. If not, a notice of rejection is given (step A6). 3. When it is determined that all VPs that can accommodate the call can be accepted, acceptance of the call is permitted.

(4) Processing of the call reception processing unit B in the case of the best effort class call reception processing In the case of the best effort class call reception, the call reception processing unit B
Performs the following processing (see FIG. 4). 1. If the peak cell rate of the best-effort class call for which a reception request has been made is equal to or less than the total VP capacity, notification is made that the reception of the requested best-effort class call is acceptable. If not, a notification of rejection is given (step B1). 2. If it is determined that all VPs that can accommodate the call can be accepted, the acceptance of the call is permitted.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and a design change or the like may be made without departing from the gist of the present invention. The present invention is also included in the present invention. For example, in the process of calculating the cell loss rate * B,

[Equation 56] And the case where Г = K is also applicable to the present invention.

[0047]

According to the present invention, for a plurality of service categories, whether or not a call belonging to the service category can be accepted depends on the quality of the service category and whether or not the quality of other service categories is affected. It is estimated in consideration of the multiplexing effect depending on the output buffer capacity, and based on the estimation, it is determined whether the call can be accepted. In addition, the process of the determination is completed in a fixed time regardless of the number of calls requested to be accepted and the output buffer capacity of the exchange. As a result, it is possible to appropriately determine the multiplexing effect and to control the admission of calls that can be processed in real time in correspondence with a plurality of service categories.

[Brief description of the drawings]

FIG. 1 shows an AT according to the prior art and one embodiment of the present invention
FIG. 4 is a block diagram illustrating a configuration example of an output buffer provided in the M exchange.

FIG. 2 is a block diagram showing a configuration example of a call admission control unit 2 according to the present invention.

FIG. 3 is a flowchart illustrating a processing example of a call reception processing unit A according to the present invention.

FIG. 4 is a flowchart illustrating a processing example of a call reception processing unit B according to the present invention.

FIG. 5 is a block diagram showing an example of an ATM network using a conventional call admission control unit 1;

FIG. 6 is a block diagram illustrating a configuration example of a call admission control unit 1 according to a conventional technique.

FIG. 7 is a flowchart illustrating a processing example of a CBR call reception processing unit 1b according to the related art.

FIG. 8 shows a conventional RtVBR call reception processing unit 1c.
9 is a flowchart illustrating an example of the processing of FIG.

FIG. 9 shows an NrtVBR call reception processing unit 1 according to the prior art.
It is a flowchart which shows the example of a process of d.

FIG. 10 is a flowchart illustrating a processing example of a best effort class call reception processing unit 1e according to the related art.

[Explanation of symbols]

 2 Call admission control units A, B Call admission processing unit C Service category check unit

Claims (10)

[Claims] The present invention uses three quantities of a peak cell rate, an average cell rate, and a maximum burst size as traffic parameters for each VBR call. A real-time cell loss rate estimation technique characterized by estimating the cell loss rate as follows. For each VBR call i, the peak cell rate r
_i , average cell rate a _i , and maximum burst size B _i
Based on the above, the following amounts are calculated and stored. (Equation 1) Here, INT (x) is a minimum integer equal to or larger than x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). Г is the VB of the multiplexer
When the output buffer capacity for R is K (cell), it is determined by Г = K + 1. Using the above P _i , S _i , α _i , Г, the cell loss rate estimated value * B is calculated by the following equation. (Equation 2) Here, N is a positive integer of 4 or more (recommended value N = 10). It is. Here, Σ is a set of VBR calls. D = max (C ₃ , C _L ), and It is. 2. A method for receiving a connection request for a call belonging to one of a plurality of service categories for which priorities have been set, classifying the received connection request based on a service category required by the connection request. A step of evaluating the quality of a service category requested by the connection request based on the cell loss rate estimating method according to claim 1, wherein it is assumed that the received connection request has been accepted; Is evaluated for each service category based on the cell loss rate estimating method according to claim 1, and based on a result of the evaluation, whether or not the received connection request is acceptable is determined, and the connection determined to be acceptable is determined. A multi-class ATM call admission control method, characterized in that a request call is permitted to store a cell of the call in a buffer. 3. The buffer is provided for each service category, the priority is set between each buffer, and cells stored in each buffer are all cells having higher priority than the buffer. 3. The multi-class ATM call admission control method according to claim 2, wherein the transfer is performed to the transmission line only when no cell exists in the buffer. 4. The process of quality evaluation for each service category, wherein the call of the service category requested by the received connection request and the call of the service category having a lower priority than the service category are multiplexed. Estimating the cell loss rate for the traffic, assuming that all lost cells based on the traffic cell loss rate belong to the lower priority service category, and the cell loss of the lower priority service category in the assumption 4. The multi-class ATM call admission control method according to claim 2, wherein the rate is estimated. 5. In the step of determining whether the received connection request is accepted, the cell loss rate of a service category requested by the received connection request is not more than a specified cell loss rate value set for the service category. And if the cell loss rate estimated for each of the low priority service categories is equal to or less than a specified cell loss rate value set for the service category, the received connection request can be accepted. 5. The multi-class ATM call admission control method according to claim 4, wherein: 6. A computing device for each VBR call i, which calculates the following quantities based on the peak cell rate r _i , the average cell rate a _i , and the maximum burst size B _i : (However, INT (x) is a minimum integer equal to or larger than x. L is a cell length (bit / cell). C is a VP capacity (transmission speed bit / cell). Of VB
When the output buffer capacity for R is K (cell), it is determined by Г = K + 1. And a storage device for holding these computational amounts, and using the above P _i , S _i , α _i , Г, the following procedure: And a calculating device for calculating the estimated value of the cell loss rate * B. Here, N is a positive integer of 4 or more (recommended value N = 10). It is. Here, Σ is a set of VBR calls. In addition, D = max (C ₃ , C _L ), and It is. 7. A means for receiving a connection request for a call belonging to any one of a plurality of service categories of which priorities are set, and for evaluating the quality of another service category for each service category, Assuming that the received connection request has been accepted, the quality of the service category requested by the connection request is evaluated using the cell loss rate estimation device according to claim 6, and the quality of another service category is evaluated. An evaluation means for evaluating, for each service category, using the cell loss rate estimation device according to claim 6, a determination means for determining whether or not the received connection request can be accepted based on a result of the evaluation; Multi-class ATM, comprising: permitting means for permitting a call of a connection request determined to be possible to be stored in a buffer of the call cell. Call admission control device. 8. The buffer is provided for each service category, the priority is set between each buffer, and cells stored in each buffer are all cells having a higher priority than the buffer. 8. The multi-class ATM call admission control device according to claim 7, wherein the transfer is performed to the transmission line only when no cell exists in the buffer. 9. The cell loss ratio for the traffic obtained by multiplexing a call of a service category requested by the received connection request and a call of a service category having a lower priority than the service category. Estimating means for estimating the cell loss rate of the low priority service category under the assumption that all lost cells based on the cell loss rate of the traffic belong to the low priority service category. 9. The multi-class ATM call admission control device according to claim 7, further comprising an estimating unit that performs the estimation. 10. The determining means, wherein the cell loss rate of a service category requested by the received connection request is equal to or less than a cell loss rate specified value set for the service category, and the low priority 10. The received connection request can be accepted if a cell loss rate estimated for each service category is equal to or less than a specified cell loss rate set for the service category. Multi-class ATM call admission control device.