JP2006246119A - Network system for realizing quality assurance service using priority control, call admission judgment method, and program thereof - Google Patents

Abstract

A call admission determination method based on a virtual buffer / trunk model method is applicable to a network node that performs priority control, and can be extended to a form that can guarantee the quality of a plurality of classes.
A virtual maximum buffer capacity is determined by forming a set of a priority class flow of a newly accepted call and a priority class flow having a higher priority than the priority class (steps 3 and 4). Similarly, for a class with a low priority, a set of a flow of the own class and a flow of a priority class having a higher priority than the own class is similarly formed, and the virtual maximum buffer capacity is sequentially obtained (step 6). To 9), based on whether the priority class of the newly accepted call and the virtual maximum buffer capacity of each class having a lower priority than the priority class exceed the buffer amount provided for each class (step 5). 10), it is determined whether or not new acceptance is possible (steps 12 and 13).
[Selection] Figure 12

Description

  The present invention relates to a priority control network system for providing a quality assurance type service in an IP (Internet Protocol) network or an MPLS (Multi Protocol Label Switching) network, a call admission determination method in the system, and a program thereof.

Broadband lines are being offered to users at low prices, and the Internet is rapidly spreading. Various services have been provided via the Internet, and communication quality has become important. Especially for real-time video and audio services, the data transfer quality on the network has a great influence, but since there is no mechanism to guarantee the data transfer quality on the Internet, the network is now constructed as an IP closed network, Providing quality assurance services in combination with technology that guarantees data transfer quality is being considered.
In an IP network, service models for guaranteeing data transfer quality are mainly classified into Inserv and Diffserv studied in IETF (Internet Engineering Task Force).

  Inserv is a model that receives a service according to the secured quality after securing the bandwidth on the network path. In the Inserv model, RSVP (Resource Reservation Protocol), which is a protocol for reserving a bandwidth on a network path with end-to-end, uses a service class (Guaranteed Service) that strictly guarantees delay and packet loss rate, or priority. A service class (Controlled-load Service) is provided. The RSVP request is forwarded by each forwarding node in the network, and the forwarding node that receives the request determines whether or not the requested service can be provided based on the bandwidth information to be managed. A band is secured by end-to-end and a connection is established.

  The RSVP request includes a traffic rule according to the token packet model, and secures a bandwidth according to the token packet parameter. However, in order to provide a quality assurance type service, it is necessary to manage all the information related to RSVP in the network forwarding node in real time and to perform packet forwarding in the Inserv using RSVP, so that it does not scale have.

On the other hand, Diffserv is a model that performs classification by marking transfer packets in a network, and differentiates transfer quality for each class by packet scheduling in a network transfer node. In the Diffserv model, transfer quality at each network transfer node is ensured by a specified PHB (Per-Hop Behavior). The PHB corresponding to the service class defines EF (Expected Forwarding), which is completely prioritized, and AF (Assured Forwarding), which is the minimum bandwidth guarantee, and is also being implemented in commercially available network forwarding nodes.
Diffserv differentiates the transfer quality for each network forwarding node and only defines the control at each forwarding node, thus solving the problem of not scaling in Inserv.

However, in order to provide a quality assurance type service, it is necessary to make an admission decision regarding the use band unified within the service providing network, and the service provider determines the quality of service provision according to the resources in the network. There remains a challenge that must be specified.
Regarding the provision of service quality, ITU-T recommends parameter definitions, transfer quality class specifications, and service models for defining service quality. However, ITU-T Recommendation Y. The specified transfer quality in 1541 The means implemented by the service model at 1221 has not been studied, and the problem remains that the service provider must define the quality of service provision according to the resources in the network.

  As a reception determination model related to the use band, there is a virtual buffer / trunk model that performs reception determination on input traffic to the network according to token bucket parameters. In the virtual buffer / trunk model, the worst condition of traffic according to the token bucket model is modeled as ON / OFF traffic, and the network bandwidth is managed by virtually allocating a proportional buffer amount to the declared bandwidth. The management server accumulates effective bandwidth considering the buffer amount of each network forwarding node based on the following concept, and accepts a logical packet loss rate of zero.

(Maximum amount of traffic sent from token bucket)
Regarding the traffic defined by the token bucket, the maximum amount of traffic A (t) generated from time 0 to t is defined by the following equation (1).

ただし、ｍｉｎ｛｝は｛｝内の最小値、σはバケットサイズ、ρは比例係数を表している。図１は、トークンバケットで規定されるセッションフローから転送されるデータの最大量の時間経過を示す図、つまりトラヒックの最大量Ａ（ｔ）の特性曲線図である。

However, min {} represents a minimum value in {}, σ represents a bucket size, and ρ represents a proportional coefficient. FIG. 1 is a graph showing the time lapse of the maximum amount of data transferred from the session flow defined by the token bucket, that is, a characteristic curve diagram of the maximum amount of traffic A (t).

  At this time, if the maximum time during which traffic can be transmitted at the peak rate P is T, PT = σ + ρT is obtained from the equation (1), and the following equation (2) is obtained.

(Characteristics of resource amount (b, c) used by traffic sent from token bucket)
FIG. 2 is a diagram simulating that data transferred from the session flow defined by the token bucket is added to the virtual buffer / trunk system.
In FIG. 2, c is the number of links, and b is the buffer amount. As shown in FIG. 2, it is assumed that one session flow sent from a token bucket is serviced in a deterministic queuing system. v (t) is the amount of buffer used at time t, b is the maximum amount of buffer used, u (t) is the bandwidth used at time t, and c is the maximum bandwidth available, where ρ ≦ c ≦ P. When the flow sends data at the maximum value A (t), the amount of buffer used increases at a rate of Pc ≧ 0 from time 0 to T, and thereafter decreases at a rate of c−ρ. Therefore, the following equation (3) is obtained.

図３は、トークンバケットで規定されるセッションフローが仮想バッファ／トランクシステムに加わった時の仮想バッファ使用量の時間経過を示す図である。

FIG. 3 is a diagram showing the elapsed time of the virtual buffer usage when the session flow defined by the token bucket is added to the virtual buffer / trunk system.

(Virtual buffer / trunk model)
FIG. 4 is a diagram simulating that a plurality of session flows defined by the token bucket are added to the virtual buffer / trunk system.
Now, it is assumed that the session flow k (k = 1, 2,..., K) having the token bucket parameters (r _k , σ _k , P _k ) is multiplexed on the node having the buffer amount B and the link bandwidth C. Think. At this time, as shown in FIG. 4, it is considered that a link bandwidth c _k (ρ _k ≦ c _k ≦ P _k ) is virtually allocated to each session flow k. However, the total amount of virtual resources should not exceed the link bandwidth C. That is, the following expression (4) is established.

このとき、セッションフローｋが使用する仮想的なバッファリソースの最大値ｂ_ｋは、前式（３）と同様に、次式（５）で表すことができる。

At this time, the maximum value b _k of the virtual buffer resource used by the session flow k can be expressed by the following equation (5), similarly to the previous equation (3).

全フローによる実際のバッファ使用量の最大値ｂは、仮想バッファ使用量の和を上回ることはないので、次式（６）が成り立てば、論理的なパケットロスがゼロになる。

Since the maximum value b of the actual buffer usage by all flows does not exceed the sum of the virtual buffer usage, if the following equation (6) is established, the logical packet loss becomes zero.

言い換えると、式（５）を満たすＫ組の仮想リソース（ｂ_ｋ，ｃ_ｋ）に対して、式（４）および式（６）が成り立てば、当該リンクにおける論理的なパケットロスはゼロになる。
各セッションフローに割り当てる仮想リソースを決定する第一の方法は、ｃ_ｋを次式（７）で与える。なお、式（７）に関しては、Ａ．Ｅｌｗａｉｌｄ，Ｄ．Ｍｉｔｒａ ａｎｄ Ｒ．Ｈ．Ｗｅｎｔｗｏｒｔｈ，“Ａ Ｎｅｗ Ａｐｐｒｏａｃｈ ｆｏｒ Ａｌｌｏｃａｔｉｎｇ Ｂｕｆｆｅｒｓ ａｎｄ Ｂａｎｄ−ｗｉｄｔｈ ｔｏ Ｈｅｔｅｒｏｇｅｎｅｏｕｓ，Ｒｅｇｕｌａｔｅｄ Ｔｒａｆｆｉｃ ｉｎ ａｎ ＡＴＭ ｎｏｄｅ，”ＩＥＥＥ Ｊｏｕｒｎａｌ ｏｎ Ｓｅｌｅｃｔｅｄ Ａｒｅａｓ ｉｎ Ｃｏｍｍｕｎｉｃａｔｉｏｎｓ，ｖｏｌ．１３，ｎｏ．６，ｐｐ．１１１５−１１２７，１９９５．（非特許文献１参照）に記載されている。

In other words, if Equation (4) and Equation (6) hold for K sets of virtual resources (b _k , c _k ) satisfying Equation (5), the logical packet loss in the link becomes zero. .
The first method for determining the virtual resource to be assigned to each session flow is to give _ck by the following equation (7). Regarding formula (7), A.I. Elwald, D.M. Mitra and R.M. H. Wentworth, "A New Approach for Allocating Buffers and Band-width to Heterogeneous, Regulated Traffic in an ATM node," IEEE Journal on Resort Amm. 13, no. 6, pp. 1115-1127, 1995. (See Non-Patent Document 1).

この方法では、結果として得られるｂ_ｋの値が、次式（８）の関係を満たす。

In this method, the resulting b _k value satisfies the relationship of the following equation (8).

この関係が満たされると、仮想帯域と仮想バッファ量のそれぞれが本来のリソース量に占める割合が等しくなり、リソース管理が簡単になるという利点がある。
仮想リソース割り当ての第二の方法として、前式（６）で表される仮想バッファ量の総和を最小化するような割当方法が考えられている。この方式を定式化すると、次式（９）となる。

When this relationship is satisfied, there is an advantage that the ratio of the virtual bandwidth and the virtual buffer amount to the original resource amount becomes equal and resource management is simplified.
As a second method of virtual resource allocation, an allocation method that minimizes the sum of the virtual buffer amounts expressed by the above equation (6) is considered. When this method is formulated, the following equation (9) is obtained.

ただし、次式（１０）となる。

However, it becomes following Formula (10).

式（９）の解となるような仮想帯域割り当ては、以下の手順で求められる。先ず全てのフローに対してρ_ｋに等しい仮想帯域を割り当てる。その後、余った帯域Ｃ−Σρ_ｋ（ｋ＝１からＫまでの積分）については、フローごとに以下の式（１１）を用いる。

The virtual bandwidth allocation that is the solution of Equation (9) is obtained by the following procedure. First, a virtual band equal to ρ _k is assigned to all flows. Thereafter, for the remaining band C-Σρ _k (integration from k = 1 to K), the following equation (11) is used for each flow.

式（１１）で計算されたピークレート送出可能時間Ｔ_ｋについて、Ｔ_ｋの値の大きなフローから順番に、Ｐ_ｋ−ρ_ｋだけ新たに追加して割り当てていく。この方式で仮想帯域ｃ_ｋを割り当てた場合、式（６）が最小化されることが知られている。これについては、Ｆ．Ｌ．Ｐｒｅｓｔｅ，Ｚ．−Ｌ．Ｚｈａｎｇ，Ｊ．Ｋｕｒｏｓｅ ａｎｄ Ｄ．Ｔｏｗｓｌｙ，“Ｓｏｕｒｃｅ Ｔｉｍｅ Ｓｃａｌｅ ａｎｄ Ｏｐｔｉｍａｌ Ｂｕｆｆｅｒ／Ｂａｎｄｗｉｄｔｈ Ｔｒａｄｅｏｆｆ Ｈｅｔｅｒｏｇｅｎｏｕｓ Ｒｅｇｕｌａｔｅｄ Ｔｒａｆｆｉｃ ｉｎ ａ Ｎｅｔｗｏｒｋ Ｎｏｄｅ，”ＩＥＥＥ／ＡＣＭ Ｔｒａｎｓａｃｔｉｏｎｓ ｏｎ Ｎｅｔｗｏｒｋｉｎｇ，ｖｏｌ．７，ｎｏ．４，ｐｐ．４９０−５０１，Ａｕｇ．１９９９．（非特許文献２参照）に記載されている。

With respect to the peak rate transmittable time T _k calculated by the expression (11), P _k −ρ _{k is} newly added and assigned in order from the flow having the largest T _k value. It is known that Equation (6) is minimized when the virtual band _kk is assigned by this method. For this, see F.A. L. Preste, Z.M. -L. Zhang, J. et al. Kurose and D.C. Towsly, “Source Time Scale and Optimal Buffer / Bandwidth Tradeoff Heterogeneously Regulated Traffic in a Network Node,” IEEE / ACM Transactions on N. 7, no. 4, pp. 490-501, Aug. 1999. (See Non-Patent Document 2).

  The call admission determination method on condition that Equation (6) holds can guarantee the flow quality because the logical packet loss is zero and the maximum delay time at the node can be guaranteed by B / C. This is possible. Comparing the first method and the second method, the first method is advantageous in that the resource allocation calculation is simple. In the second method, the resource allocation method is complicated, but the calculated maximum buffer usage is guaranteed to be less than or equal to the maximum buffer usage calculated in the first method. More calls can be accepted when used in the case of, and there is an advantage that the accommodation efficiency is excellent.

A. Elwald, D.M. Mitra and R.M. H. Wentworth, “A New Approach for Allocating Buffers and Band-width to Heterogeneous, Regulated Traffic in an ATM node,” IEEE Journal on Assorted Ale. 13, no. 6, pp. 1115-1127, 1995. F. L. Preste, Z.M. -L. Zhang, J. et al. Kurose and D.C. Towsly, “Source Time Scale and Optimal Buffer / Bandwidth Tradeoff Heterogeneously Regulated Traffic in a Network Node,” IEEE / ACM Transactions on N. 7, no. 4, pp. 490-501, Aug. 1999.

  As described above, Inserv or Diffserv or ITU-T recommendation Y.I. By applying the virtual buffer / trunk model to the 1221 service model, it is possible to perform call admission determination with guaranteed quality. However, in the existing system, for example, quality by priority in the case where traffic flows classified into a plurality of priorities share bandwidth resources is not considered. Therefore, in a system such as Diffserv that performs priority control by providing another buffer, it is difficult to directly apply the existing method to a class other than the class with the highest priority.

(the purpose)
An object of the present invention is to enable the above-described call admission determination method based on the virtual buffer / trunk model method to be applied to a network node that performs priority control, and to be able to be extended to a form that can guarantee the quality of a plurality of classes. It is to provide a network system, a call admission determination method, and a program for realizing a quality assurance service using the.

  The present invention is a call admission control technique for guaranteeing a plurality of classes of quality in an IP network, and is composed of a priority class flow of a new acceptance call and a priority class flow having a higher priority than the priority class. To determine the virtual maximum buffer capacity, and in the same way, for a class with a lower priority than the priority class, a set of the own class flow and the priority class flow with a higher priority than the own class Then, the virtual maximum buffer capacity is obtained sequentially, and the priority class of the newly accepted call and the virtual maximum buffer capacity of each class having a lower priority than the priority class are determined as the buffer capacity ( It is characterized by judging whether new acceptance is possible or not based on whether the amount of equipment) is exceeded.

The procedure of the present invention will be specifically described. For example, assuming that priority classes 1 to 5 exist, when a new call of priority class 3 is accepted, the following procedure is performed.
a) Classes 1 and 2 have a higher priority than new calls and are considered to have no effect.
b) Assuming that classes 1 to 3 are S, the buffer maximum usage estimated value b (S1, S2, S3) in this case is obtained.
c) If the value obtained in b) above is appropriate as the maximum use amount of the buffer allocated to class 3, this is adopted. Otherwise, it may be a smaller value. (Expression will be described later).
d) Assuming that classes 1 to 4 are S, a buffer maximum usage estimated value b (S1, S2, S3, S4) in this case is obtained (this value is larger than the value obtained in b)).
e) If the value obtained in d) above is appropriate as the maximum use amount of the buffer allocated to class 4, this is adopted, and if not, it may be a smaller value. It is obtained using (the formula will be described later).
f) Assuming that classes 1 to 5 are S, the buffer maximum usage estimated value b (S1, S2, S3, S4, S5) in this case is obtained.
g) If the value obtained in d) above is appropriate as the maximum use amount of the buffer allocated to class 5, this is adopted. Otherwise, it may be a smaller value. It is obtained using (the formula will be described later).
h) If the maximum buffer usage of classes 3 to 5 obtained in c) e) g) is equal to or less than the installed capacity of each class, a new call is accepted. If any of the values exceeds the amount of equipment, the new call is rejected.

Hereinafter, the principle of the present invention will be described.
FIG. 5 is a diagram simulating how a large number of session flows defined by token buckets are added to a node system having individual buffers corresponding to a plurality of priority classes.
In the present invention, there are N types of buffers corresponding to the priority class, class 1 is the highest priority, and class N is regarded as the lowest priority, and is accommodated in the buffer of the higher priority class. In the node system shown in FIG. 5 which has a function that data is always processed preferentially over data stored in a low-priority class buffer, the buffer length corresponding to class N is B _N , the maximum processing speed (bandwidth ) Is C, quality determination based on the priority class and traffic parameters of each traffic flow is performed by the following means.
Assume that a set of all flows accommodated in the node is S = {1,..., K}, and a set of flows of priority class _n is represented by Sn. At this time, ∪S _n = S (a set from n = 1 to N) holds, and if i ≠ j, S _i ∩S _j = φ. For priority class 1 flows, the bandwidth can always be preferentially used, so a virtual buffer / trunk model method on a node system having resources (B ₁ , C) may be considered. Therefore,

ただし、

However,

で求められる最大バッファ使用量ｂ_Ｓ１が優先クラス１に割り当てられたバッファ量Ｂ_１以下であれば、優先クラス１の論理的パケットロスはゼロと判断できる。
図６は、優先クラス１および２のセッションフローが単一の仮想バッファ／トランクシステムに加わる様子を模した図である。
次に、優先クラス２のフローについて考えると、優先クラス３以下のフローについては考慮する必要がないが、優先クラス１のフローは無視できない。ここで、優先クラス１のバッファ使用量ｖ_Ｓ１（ｔ），と優先クラス２のバッファ使用量ｖ_Ｓ２（ｔ）および２つのクラスを同一のバッファに収容した場合、すなわち図６に示すような仮想的なシステムでのバッファ使用量ｖ_Ｓ１，_Ｓ２（ｔ）を比較すると、

If the maximum buffer usage b _S1 is allocated buffer amount B ₁ than the priority class 1 sought, logical packet loss priority class 1 can be determined to be zero.
FIG. 6 is a diagram simulating how priority class 1 and 2 session flows join a single virtual buffer / trunk system.
Next, when considering the flow of priority class 2, it is not necessary to consider the flow of priority class 3 or lower, but the flow of priority class 1 cannot be ignored. Here, when the receiving buffer usage v _S1 of priority class 1 _(t), and buffer usage v _S2 of priority class 2 _(t) and two classes in the same buffer, i.e., as shown in FIG. 6 Virtual The buffer usage v _S1 , _S2 (t) in a typical system

という関係が成り立つ。
従って、ｖ_Ｓ２（ｔ）≦ｖ_Ｓ１，_Ｓ２（ｔ）より、優先クラス２の最大バッファ使用量は図６の仮想システムの最大バッファ使用量で抑えられる。この最大バッファ使用量をｂ_Ｓ１，_Ｓ２とすると、

This relationship holds.
Therefore, from v _S2 (t) ≦ v _S1 , _S2 (t), the maximum buffer usage of the priority class 2 can be suppressed by the maximum buffer usage of the virtual system in FIG. If the maximum buffer usage is b _S1 and _S2 ,

ただし、

However,

である。ｂ_{Ｓ１，Ｓ２}は集合Ｓ_１∪Ｓ_２のフローが加わった場合の最大バッファ使用量であり、既存技術と同様の方法で求められる。このとき、

It is. b _{S1 and S2} are the maximum buffer usage when the flow of the set S ₁ ∪S ₂ is added, and can be obtained by the same method as the existing technology. At this time,

を満たせば、優先クラス２の論理的パケットロスはゼロと判断できる（第一の判定方法）。
第一の判定方法は、既存の方法を直接適用することが可能であり、計算は比較的容易であるが、優先クラス１のバッファ使用量を無視しているため、その分だけ効率が上がらない。そこで、以下に述べる第二の判定方法が考えられる。
フローｋが最大速度でデータ転送を行う場合、時刻０からＴ_ｋ＝σ_ｋ／（Ｐ_ｋ−ρ_ｋ）まではピークレートＰ_ｋ，それ以降ではトークンレートρ_ｋでのデータ転送となる。従って、時刻ｔでの転送レートｒ_ｋ（ｔ）は

If it satisfies, it can be determined that the logical packet loss of the priority class 2 is zero (first determination method).
The first determination method can directly apply the existing method, and the calculation is relatively easy. However, since the buffer usage of the priority class 1 is ignored, the efficiency is not improved accordingly. . Therefore, a second determination method described below can be considered.
When the flow k performs the data transfer at the maximum speed, the data transfer is performed at the peak rate P _k from time 0 to T _k = σ _k / (P _k −ρ _k ) and at the token rate ρ _k thereafter. Therefore, the transfer rate r _k (t) at time t is

で表される。ただし、１_ＸはＸが真ならば１、偽ならば０をとる関数である。
いま、ｉ_ｋを、優先クラス１の中で式（１１）で得られたＴ_ｋの値がｋ番目に大きいフローとする（ｉ_ｋ∈Ｓ_１）と、定義より、Ｔ_ｉ１≧Ｔ_ｉ２≧・・・・・が成り立つ。

It is represented by However, 1 _X is a function that takes 1 if X is true and takes 0 if false.
Assuming that i _k is a flow in which the value of T _k obtained by the expression (11) in the priority class 1 is the k-th largest (i _k ∈ S ₁ ), T _i1 ≧ T _i2 ≧ ... is true.

が非負ならば、時刻Ｔｉ１でのバッファ使用量も非負であるから、優先クラス１のフローが時刻０から最大速度でデータ転送を行い、優先クラス１のバッファにデータが溜まり始めてから当該バッファが空になるまでの時間をＴ^（１）とすると、Ｔ^（１）≧Ｔ_ｉ１が成り立つ。
時刻Ｔ^（１）までに到着する優先クラス１のデータ量とサーバ処理量は等しいから、この時

Is non-negative, the buffer usage at time Ti1 is also non-negative, so the priority class 1 flow transfers data at the maximum speed from time 0, and the buffer is empty after data begins to accumulate in the priority class 1 buffer. Assuming that the time until is T ⁽¹⁾ , T ⁽¹⁾ ≧ T _i1 holds.
Since the data amount of the priority class 1 that arrives by time T ⁽¹⁾ is equal to the server processing amount,

が成り立つ。式（２０）を変形すると、

Holds. When formula (20) is transformed,

が得られる。
式（１９）が負の時、時刻Ｔ_ｉ１の時点でバッファ使用量は既に０、すなわちＴ^（１）≦Ｔ_ｉ１である。この時、

Is obtained.
When the expression (19) is negative, the buffer usage is already 0 at the time T _i1 , that is, T ⁽¹⁾ ≦ T _i1 . At this time,

が正ならば、Ｔ_ｉ２≦Ｔ^（１）≦Ｔ_ｉ１が成り立ち、区間（Ｔ_ｉ１Ｔ_ｉ１）でのバッファ使用量のデータ転送レートは一定であるから、バッファ使用量の推移も一定となり、

Is positive, T _i2 ≦ T ⁽¹⁾ ≦ T _i1 holds, and since the data transfer rate of the buffer usage in the section (T _i1 T _i1 ) is constant, the transition of the buffer usage is also constant,

が成り立つ。これを一般化すると、

Holds. Generalizing this,

があるｒについてＱ_ｉｒ≦０かつＱ_ｉｒ＞０ならば、

If Q _ir ≦ 0 and Q _ir > 0 for some r,

が成り立つ。
今、優先クラス２のフローが時刻０から最大速度でデータ転送を行ったと仮定すると、時刻０から時刻Ｔ^（１）までの間は全ての帯域が優先クラス１のデータを処理するために使用されているので、優先クラス２のバッファ使用量ｖ_Ｓ２（ｔ）は増加する。時刻Ｔ^（１）における優先クラス２のフロー全体の転送レート

Holds.
Assuming that the priority class 2 flow transfers data at the maximum speed from time 0, all the bandwidth is used to process the priority class 1 data from time 0 to time T ^(1). Therefore, the buffer usage v _S2 (t) of the priority class 2 increases. Transfer rate of entire priority class 2 flow at time T ⁽¹⁾

が、この時点で優先クラス２が利用可能な帯域より小さい場合、すなわち

If priority class 2 is less than the available bandwidth at this point, ie

であれば、時刻Ｔ^（１）以降ｖ_Ｓ２（ｔ）は減少する。従って、優先クラス２のバッファ使用量はｔ＝Ｔ^（１）の時点で最大となり、

If so, v _S2 (t) decreases after time T ⁽¹⁾ . Therefore, the buffer usage of the priority class 2 becomes the maximum at the time of t = T ⁽¹⁾ ,

で与えられる。逆に、

Given in. vice versa,

が成り立つ場合、時刻Ｔ^（１）以降もｖ_Ｓ２（ｔ）は増加する。この場合、優先クラス１のバッファ使用量が常に０であるので、優先クラス２の最大バッファ使用量は前述のｂ_{Ｓ１，Ｓ２}に等しい。従って、第二の判定方法では、式（２７）が成り立つ場合には、式（２８）の値、それ以外ならば式（１５）の値を優先クラス２の最大バッファ使用量ｂ_Ｓ２とし、ｂ_Ｓ２≦Ｂ_２が成り立てば、優先クラスより高い優先度のクラス全体を上位クラス、上位クラスと当該クラスを併せたものを全体クラスとみなすことで、優先クラス２についての判定方法と同様の処理が可能となる。すなわち、優先クラスｎについては、第一の判定方法では、

V _S2 (t) increases after time T ⁽¹⁾ . In this case, since the buffer usage of the priority class 1 is always 0, the maximum buffer usage of the priority class 2 is equal to the aforementioned b _{S1 and S2} . Therefore, in the second determination method, when the expression (27) is satisfied, the value of the expression (28) is set as the maximum buffer usage b _S2 of the priority class 2 otherwise, and the value of the expression (15) is set as b. if _S2 ≦ B ₂ is Naritate, whole class upper class higher than the priority class priority, it regarded as the entire class that combined upper class and the class, the same processing as the determination methods for priority 2 It becomes possible. That is, for the priority class n, in the first determination method,

ただし、

However,

とし、

age,

を満たせば論理的パケットロスはゼロと判定する。第二の判定方法では、優先クラス１〜ｎ−１を一つにまとめた仮のクラスを想定し、式（１９）−（２５）を用いた手順により、このＴ^{（ｎ−１）}を求める。この時

If it satisfies, the logical packet loss is determined to be zero. In the second determination method, a provisional class in which priority classes 1 to n-1 are combined into one is assumed, and T ^(n-1) is obtained by a procedure using equations (19) to (25). . At this time

が成り立てば、

If

を、式（３３）が成り立たなければ式（３０）を優先クラスｎの最大バッファ使用量ｖ_{Ｓ１，Ｓ２}（ｔ）とし、ｖ_{Ｓ１，Ｓ２}（ｔ）Ｂｎ以下であれば論理パケットロスはゼロと判定する。

If the equation (33) does not hold, the equation (30) is set to the maximum buffer usage v _{S1, S2} (t) of the priority class n, and if v _{S1, S2} (t) Bn or less, the logical packet loss is zero. judge.

According to the present invention, it is possible to provide a method for obtaining the maximum buffer usage amount of an arbitrary priority class based on the parameters of the class and higher class. As a result, as shown in the first to third embodiments, it becomes possible to determine the presence or absence of data loss due to buffer overflow for all classes, and call admission control of multiple priority classes by the procedure shown in the fourth embodiment. Realize the law.
With the configuration of the present invention, it is possible to realize not only the priority class of a newly accepted call but also the priority class having a lower priority than the class, that is, the quality assurance service for all priority classes.

  Conventionally, the method of calculating the maximum value of the buffer usage based on the traffic flow reporting parameter in advance is effective for call admission determination because it is possible to know in advance whether there is data loss due to buffer overflow. With regard to this technology, existing studies have a limitation that it can be applied only to a single buffer. However, future Internet services take service differentiation into account, and in the technique such as DiffServ, priority control based on control by a plurality of buffers on a network system is essential. For systems with multiple buffers, the existing technology can determine only the quality of the class with the highest priority, but there is no determination method for other priority classes. Alternatively, there has been a problem that there is only a method whose accuracy is not guaranteed. In the present invention, this problem can be solved by implementing the call admission control method for multiple priority classes by the procedure of the fourth embodiment.

FIG. 7 is a diagram showing traffic flow parameters used in the embodiment of the present invention.
Assume that a plurality of traffic flows having the following parameters are classified into two priority classes and accommodated in a network node. The read bandwidth at the network node is assumed to be C = 150 (Mbps).
As shown in FIG. 7, the traffic flow parameters P, ρ, σ, and T are set and registered for each call type 1 to 4 (Mbps) and time (sec). For example, a call type is assigned to each priority class, such as call type 1 for priority class 1 and call type 2 for priority class 2.

Example 1
FIG. 8 is a diagram illustrating a lapse of time of buffer usage for each priority class according to the first embodiment of the present invention.
In this embodiment, a case is considered where 30 traffic flows are accommodated in a network node. k = 1,..., 10 is a call class 1 traffic flow, priority class 1, k = 11,..., 20 is a call class 2 traffic flow, priority class 1, k = 21,. 30 is a traffic flow of the call type 3 and belongs to the priority class 2.
The maximum buffer usage b _S1 of the priority class 1 is obtained from the equations (12) and (13).

ただし、ｃ^（１），ｃ^（２）は呼種１，２へ与える仮想帯域量で、２Ｍｂｐｓから１０Ｍｂｐｓの間の値である。式（３５）はｃ^（１）＝５，ｃ^（２）＝１０の時最小化され、ｂ_Ｓ１＝５０（Ｍｂｐｓ）となる。
次に、第一の判定方法による優先クラス２のバッファ最大使用量は、式（１５）および（１６）より、

However, c ⁽¹⁾ and c ⁽²⁾ are virtual bandwidth amounts given to the call types 1 and 2 and are values between 2 Mbps and 10 Mbps. Equation (35) is minimized when c ⁽¹⁾ = 5, c ⁽²⁾ = 10, and b _S1 = 50 (Mbps).
Next, the maximum buffer usage of the priority class 2 according to the first determination method is obtained from the equations (15) and (16).

ただし、ｃ^（１），ｃ^（２），ｃ^（３）は呼種１，２，３へ与える仮想帯域量で、２Ｍｂｐｓから１０Ｍｂｐｓの間の値である。式（３６）はｃ^（１）＝２，ｃ^（２）＝３，ｃ^（３）＝１０の時最小化され、ｂ_{Ｓ１，Ｓ２}＝２２０（Ｍｂｉｔ）となる。
第二の判定方法による優先クラス２のバッファ最大使用量については、式（１９）の値は非負であるので、式（２１）を用いて、Ｔ^（１）＝２４／１１を得る。時刻Ｔ^（１）における優先クラス２のフロー全体の転送レートはｒ^（２）（２４／１１）＝１００（Ｍｂｐｓ）であり、これはこの時点で優先クラス２が利用可能な帯域Ｃ−σ_ｋ∈Ｓ１ｒ_ｋ（２４／１１）＝１１０（Ｍｂｐｓ）より小さい。従って、優先クラス２のバッファ最大使用量は、式（２８）より、

However, c ⁽¹⁾ , c ⁽²⁾ , and c ⁽³⁾ are virtual bandwidth amounts given to the call types 1, 2, and 3, and are values between 2 Mbps and 10 Mbps. Equation (36) is minimized when c ⁽¹⁾ = 2, c ⁽²⁾ = 3, c ⁽³⁾ = 10, and b _{S1, S2} = 220 (Mbit).
Regarding the maximum buffer usage of priority class 2 by the second determination method, since the value of Equation (19) is non-negative, T ⁽¹⁾ = 24/11 is obtained using Equation (21). The transfer rate of the entire priority class 2 flow at time T ⁽¹⁾ is r ⁽²⁾ (24/11) = 100 (Mbps), which is the bandwidth C-σ _k available to the priority class 2 at this time. _ΕS1 r _k (24/11) = less than 110 (Mbps). Therefore, the maximum buffer usage of priority class 2 is given by equation (28):

で得られる。この実施例では、第二の判定方法による優先クラス２の最大バッファ使用量は、第一の判定方法とほとんど変わらない。

It is obtained with. In this embodiment, the maximum buffer usage of priority class 2 by the second determination method is almost the same as that of the first determination method.

(Example 2)
FIG. 9 is a diagram illustrating the elapsed time of the buffer usage for each priority class according to the second embodiment of the present invention.
In this embodiment, a case is considered where 30 traffic flows are accommodated in a network node. k = 1,..., 10 is a call class 1 traffic flow and priority class 2, k = 11,..., 20 is a call class 2 traffic flow and priority class 1, k = 21,. 30 is a traffic flow of call type 3 and belongs to priority class 1.
The maximum buffer usage b _S1 of the priority class 1 is obtained from the equations (12) and (13).

ただし、ｃ^（２）ｃ^（３）は呼種２，３へ与える仮想帯域量で、２Ｍｂｐｓから１０Ｍｂｐｓの間の値である。式（３８）はｃ^（２）＝５，ｃ^（３）＝１０の時に最小化され、ｂ_Ｓ１＝１００（Ｍｂｐｓ）となる。
次に、第一の判定方法による優先クラス２のバッファ最大使用量は、式（１５）および（１６）より、

However, c ⁽²⁾ c ⁽³⁾ is a virtual bandwidth amount given to the call types 2 and 3, and is a value between 2 Mbps and 10 Mbps. Equation (38) is minimized when c ⁽²⁾ = 5, c ⁽³⁾ = 10, and b _S1 = 100 (Mbps).
Next, the maximum buffer usage of the priority class 2 according to the first determination method is obtained from the equations (15) and (16).

ただし、ｃ^（１），ｃ^（２），ｃ^（３）は呼種１，２，３へ与える仮想帯域量で、２Ｍｂｐｓから１０Ｍｂｐｓの間の値である。式（３９）は、ｃ^（１）＝２，ｃ^（２）＝３，ｃ^（３）＝１０の時に最小化され、ｂ_{Ｓ１，Ｓ２}＝２２０（Ｍｂｐｓ）となる。
第二の判定方法による優先クラス２のバッファ最大使用量については、式（１９）の値は非負であるので、式（２１）を用いて、Ｔ^（１）＝４０／１１を得る。時刻Ｔ^（１）における優先クラス２のフロー全体の転送レートはｒ^（２）（４０／１１）＝２０（Ｍｂｐｓ）であり、これはこの時点で優先クラス２が利用可能な帯域Ｃ−σ_ｋ∈Ｓ１，ｒ_ｋ（４０／１１）＝１１０（Ｍｂｐｓ）より小さい。従って、優先クラス２のバッファ最大使用量は、式（２８）より、

However, c ⁽¹⁾ , c ⁽²⁾ , and c ⁽³⁾ are virtual bandwidth amounts given to the call types 1, 2, and 3, and are values between 2 Mbps and 10 Mbps. Equation (39) is minimized when c ⁽¹⁾ = 2, c ⁽²⁾ = 3, c ⁽³⁾ = 10, and b _{S1, S2} = 220 (Mbps).
As for the buffer maximum usage amount of priority class 2 according to the second determination method, the value of equation (19) is non-negative, and therefore T ⁽¹⁾ = 40/11 is obtained using equation (21). The transfer rate of the entire flow of the priority class 2 at time T ⁽¹⁾ is r ⁽²⁾ (40/11) = 20 (Mbps), and this is the bandwidth C-σ _{k that} can be used by the priority class 2 at this time. _{It is} smaller than _εS1 , r _k (40/11) = 110 (Mbps). Therefore, the maximum buffer usage of priority class 2 is given by equation (28):

で得られる。この実施例では、第二の判定方法による優先クラス２の最大バッファ使用量は約１５３Ｍｂｐｓであり、第一の判定方法（２２０Ｍｂｐｓ）に比べておよそ３０％低い値を求めることが可能となる。

It is obtained with. In this embodiment, the maximum buffer usage of priority class 2 according to the second determination method is about 153 Mbps, and a value approximately 30% lower than that of the first determination method (220 Mbps) can be obtained.

(Example 3)
FIG. 10 is a diagram illustrating a lapse of time of buffer usage for each priority class according to the third embodiment of the present invention.
In this embodiment, a case is considered where 30 traffic flows are accommodated in a network node. k = 1,..., 10 is a call class 1 traffic flow, priority class 2, k = 11,..., 25 is a call class 2 traffic flow, priority class 1, k = 26,. 30 is a traffic flow of call type 4 and belongs to priority class 1.
The maximum buffer usage b _S1 of the priority class 1 is obtained from the equations (12) and (13).

ただし、ｃ^（２），ｃ^（４）は呼種２，４へ与える仮想帯域量で、２Ｍｂｐｓから１０Ｍｂｐｓの間の値である。式（４１）はｃ^（２）＝２０／３，ｃ^（４）＝１０の時に最小化され、ｂ_Ｓ１＝１００（Ｍｂｐｓ）となる。
次に、第一の判定方法による優先クラス２のバッファ最大使用量は、式（１５）および（１６）より、

However, c ⁽²⁾ and c ⁽⁴⁾ are virtual bandwidth amounts given to the call types 2 and 4 and are values between 2 Mbps and 10 Mbps. Equation (41) is minimized when c ⁽²⁾ = 20/3, c ⁽⁴⁾ = 10, and b _S1 = 100 (Mbps).
Next, the maximum buffer usage of the priority class 2 according to the first determination method is obtained from the equations (15) and (16).

ただし、ｃ^（１），ｃ^（２），ｃ^（４）は呼種１，２，４へ与える仮想帯域量で、２Ｍｂｐｓから１０Ｍｂｐｓの間の値である。式（４２）はｃ^（１）＝２，ｃ^（２）＝１６／３，ｃ^（４）＝１０の時に最小化され、ｂ_{Ｓ１，Ｓ２}＝２２０（Ｍｂｐｓ）となる。
第二の判定方法による優先クラス２のバッファ最大使用量については、式（１９）の値は負であるので、式（２２），（２３）により、Ｔ^（１）＝２４／７を得る。時刻Ｔ^（１）における優先クラス２のフロー全体の転送レートはｒ^（２）（２４／７）＝２０（Ｍｂｐｓ）であり、これはこの時点で優先クラス２が利用可能な帯域Ｃ−σ_ｋ∈Ｓ１，ｒ_ｋ（２４／７）＝７０（Ｍｂｐｓ）より小さい。従って、優先クラス２のバッファ最大使用量は、式（２８）より、

However, c ⁽¹⁾ , c ⁽²⁾ and c ⁽⁴⁾ are virtual bandwidth amounts given to the call types 1, 2 and 4 and are values between 2 Mbps and 10 Mbps. Equation (42) is minimized when c ⁽¹⁾ = 2, c ⁽²⁾ = 16/3, c ⁽⁴⁾ = 10, and b _{S1, S2} = 220 (Mbps).
Regarding the buffer maximum usage amount of priority class 2 according to the second determination method, since the value of the equation (19) is negative, T ⁽¹⁾ = 24/7 is obtained from the equations (22) and (23). The transfer rate of the entire flow of the priority class 2 at time T ⁽¹⁾ is r ⁽²⁾ (24/7) = 20 (Mbps), and this is the bandwidth C-σ _{k that} can be used by the priority class 2 at this time. _{It is} smaller than _{∈ S1} , r _k (24/7) = 70 (Mbps). Therefore, the maximum buffer usage of priority class 2 is given by equation (28):

で得られる。

It is obtained with.

Example 4
FIG. 11 is a diagram illustrating the passage of time of the buffer usage for each priority class according to the fourth embodiment of the present invention.
In the present embodiment, a case is considered where 40 traffic flows are accommodated in a network node. k = 1,..., 10 is a call class 1 traffic flow, priority class 1, k = 11,..., 20 is a call class 2 traffic flow, priority class 1, k = 21,. 40 is a traffic flow of the call type 3 and belongs to the priority class 2.
The maximum buffer usage b _S1 of the priority class 1 is the same as the traffic flow of the priority class 1 as in the first embodiment, and therefore b _S1 = 50 (Mbps).
Next, the maximum buffer usage of the priority class 2 according to the first determination method is obtained from the equations (15) and (16).

ただし、ｃ^（１），ｃ^（２），ｃ^（３）は呼種１，２，３へ与える仮想帯域量で、２Ｍｂｐｓから１０Ｍｂｐｓの間の値である。式（４４）はｃ^（１）＝２，ｃ^（２）＝２，ｃ^（３）＝５．５の時に最小化され、ｂ_Ｓ１＝５１０（Ｍｂｐｓ）となる。
第二の判定方法による優先クラス２のバッファ最大使用量については、式（１９）の値は非負であるので、式（２１）を用いて、Ｔ^（１）＝２４／１１を得る。時刻Ｔ^（１）における優先クラス２のフロー全体の転送レートはｒ^（２）（２４／１１）＝２００（Ｍｂｐｓ）であり、これはこの時点で優先クラス２が利用可能な帯域Ｃ−σ_ｋ∈Ｓ１，ｒ_ｋ（２４／１１）＝１１０（Ｍｂｐｓ）より大きい。従って、優先クラス２のバッファ最大使用量は、第一の判定方法と等しく、ｂ_Ｓ１＝５１０（Ｍｂｐｓ）となる。

However, c ⁽¹⁾ , c ⁽²⁾ , and c ⁽³⁾ are virtual bandwidth amounts given to the call types 1, 2, and 3, and are values between 2 Mbps and 10 Mbps. Equation (44) is minimized when c ⁽¹⁾ = 2, c ⁽²⁾ = 2 and c ⁽³⁾ = 5.5, and b _S1 = 510 (Mbps).
Regarding the maximum buffer usage of priority class 2 by the second determination method, since the value of Equation (19) is non-negative, T ⁽¹⁾ = 24/11 is obtained using Equation (21). The transfer rate of the entire flow of the priority class 2 at time T ⁽¹⁾ is r ⁽²⁾ (24/11) = 200 (Mbps), and this is the bandwidth C-σ _{k that} can be used by the priority class 2 at this time. _{It is} larger than ∈ _S1 , r _k (24/11) = 110 (Mbps). Therefore, the maximum buffer usage of priority class 2 is equal to that of the first determination method, and b _S1 = 510 (Mbps).

Although the first to fourth embodiments have been described above, the characteristics of each embodiment will be described with respect to the time lapse diagram of the buffer usage amount for each priority class according to FIGS. 9 to 11.
First, the first embodiment is an example in which the buffer usage of the priority class 2 becomes the maximum at the time T ⁽¹⁾ when the buffer usage of the priority class 1 becomes zero. However, under the conditions in the first embodiment, as shown in FIG. 8, the sum of the buffer usage amounts of the priority class 1 and the priority class 2, that is, the time point when the total buffer usage amount reaches the maximum value b _{S1, S2} and T ⁽ The interval of ¹⁾ is short. Accordingly, the maximum buffer usage amount b _S2 of the priority class 2 estimated by using the second determination method is slightly smaller than the maximum buffer usage amounts b _{S1 and S2} obtained by the first determination method. It is an example where the effect of adopting the second determination method is small.

Next, in the second embodiment, similarly to the first embodiment, the buffer usage of the priority class 2 becomes the maximum at the time T ⁽¹⁾ when the buffer usage of the priority class 1 becomes 0. In the condition in the second embodiment, as shown in FIG. 9, the sum of the buffer usage amounts of the priority class 1 and the priority class 2, that is, the time when the total buffer usage reaches the maximum values b _{S1 and S2} and T ⁽¹⁾ Is larger than that in the first embodiment.
Therefore, the difference between the maximum buffer usage amount b _{S2 of the} priority class 2 estimated by using the second determination method and the maximum buffer usage amounts b _{S1 and S2} obtained by the first determination method increases, Compared to Example 1, this is a great example of the effect of adopting the second determination method.

Next, in the third embodiment, as in the first and second embodiments, the buffer usage of the priority class 2 becomes the maximum at the time T ⁽¹⁾ when the buffer usage of the priority class 1 becomes 0. In Examples 1 and 2, since the value of Equation (19) was non-negative, T ⁽¹⁾ can be obtained directly from Equation (21). However, under the conditions of Example 3, the value of Equation (19) is negative. Therefore, T ⁽¹⁾ needs to obtain the points in time T _i1 and T _{i2 at} which the equation (22) is established, and further uses the equation (23), which is an example in which the amount of calculation increases. It is different from the example. Further, as shown in FIG. 10, T ⁽¹⁾ obtained in this way has passed a certain amount of time from the time point when the total buffer usage reaches the maximum values b _{S1 and S2} . Therefore, the difference between the estimated values b _S2 and b _{S1 and S2} by the second determination method becomes large, which is an example of a great effect of adopting the second determination method.

Next, in the fourth embodiment, unlike the previous three examples, at the time T ⁽¹⁾ when the buffer usage of the priority class 1 becomes 0, the buffer usage of the priority class 2 is not the maximum. is there. In this case, as shown in FIG. 11, the maximum buffer usage b _b2 of the priority class 2 calculated by the second determination method is the maximum buffer usage b _S1 obtained by the first determination method. _{, S2} and the same value, it is an example in which the second determination method is not effective.

(Example 5)
FIG. 12 is an operation flowchart of the call admission determination method according to the fifth embodiment of the present invention.
In this embodiment, it is assumed that a call acceptance request from a user is sent to a network node via a signaling network, and a new call acceptance determination is performed on the network node that performs priority control.
(Step 1) The call (K) requesting new acceptance declares the token bucket parameters (P _k , ρ _k , σ _k ) and the priority class m.
(Step 2) The node system on the route of the new call K receives the declaration parameter and starts a procedure for judging whether or not quality assurance can be performed when a new call is accepted. Priority to the set Sm of class m temporarily added new call K, also determine the value of T _K using equation (11).
(Step 3) If the sum of the peak rates of calls of all classes Σ _kεS P _k is equal to or less than C, each class does not wait for more than one packet, and therefore accepts a new call K (Step 3). 12). Otherwise, go to the next step.
(Step 4) If the priority class of the new call K is 1, b _S1 is calculated using Equation (12), and the process proceeds to the next step. Otherwise, the process proceeds to step 6 to estimate the quality after the priority class m.

(Step 5) the amount B ₁ buffer equipment node system uses the priority class 1, if the b _S1 than that obtained in step 4, the loss of the Priority 1 determines that no quality priority class 2 or later Estimate (go to step 6). If b _S1 > B ₁ , the quality of the priority class 1 cannot be guaranteed, so the acceptance of the new call K is rejected (to step 13).
(Step 6) To determine the quality of the priority class n, T ⁽ⁿ⁻¹⁾ , r ⁽ⁿ⁾ , T ⁽ⁿ⁻¹⁾ , and (18), (21) to (25) are used. Σ _{kεS1∪Sn−1} r _k (T ⁽ⁿ⁻¹⁾ ) is calculated.
(Step 7) The calculation method of the buffer maximum usage b _Sn of the priority class n is determined using the equation (33). If the equation (33) is established, the calculation method of step 9 is applied. Otherwise, the calculation method of step 8 is applied.
(Step 8) If equation (33) does not hold, the calculation result by equation (30) is obtained and adopted as _bSn (to step 10).

(Step 9) When the equation (33) is established, the calculation result by the equation (34) is obtained and adopted as _bSn (to step 10).
(Step 10) If the amount B _{n of} buffer facilities used by the node system for the priority class n is equal to or larger than _bSn obtained by calculation, it is determined that there is no loss of the priority class n, and the process proceeds to Step 11. If b _Sn > B _n , the quality of the priority class n cannot be guaranteed, so the acceptance of the new call K is rejected (to step 13).
(Step 11) If quality determination has been completed for all priority classes (n = N), the process proceeds to Step 12. Otherwise, the quality determination for the next priority class is continued (to step 6).
(Step 12) It is determined that there is no loss for all priority classes, the acceptance of the new call K is permitted, and the acceptance determination is terminated.
(Step 13) Since it is determined that the quality cannot be guaranteed for any of the priority classes, the new call K is removed from the set S _m of the priority classes m, the acceptance of the new call K is rejected, and the acceptance determination is terminated.

FIG. 13 is a diagram illustrating a configuration of a network node according to the fifth embodiment of the present invention.
The network node is equipped with an output interface (1) of speed C and an individual buffer group (2) having capacity Bn (n = 1,..., N) corresponding to priority classes 1 to N. Yes. In addition, a signal control device (5) for communicating information of a new call and acceptance / rejection with an external device, a call information storage device (3) for accommodating a priority class and token bucket parameters of a connected call, and acceptance / non-acceptance It has a quality calculation device (4) for performing calculation.

The signal control device (5) acquires from the external signal line the connection request to the network node of the new call (step 1) in FIG. 12, the call declaration parameter of the call, and the termination notification of the connected call. It has a function of transmitting the result of connection possibility of a new call made in (Step 12) or (Step 13) through an external signal line.
The call information storage device (3) stores information on token bucket parameters and priority classes declared by each connected call. 12 (step 1) in FIG. 12 temporarily stores parameters declared from a call requesting a new reception. If connection of a new call is recognized in (step 12), the parameters are continuously stored. On the contrary, when the connection of the new call is rejected in (step 13), the parameter is deleted.
Furthermore, when a notification of the termination of a connected call is transmitted to the signal control device (5), it has a function of deleting the call parameters.

The quality calculation device (4) uses the facility quantities C and B _n (n = 1,..., N) of the node system and the parameters of each call stored in the call information storage device (3) ( T _k in step 2), Σ _kεS P _k in (step 3), b _S1 in (step 4), T ⁽ⁿ⁻¹⁾ , r ⁽ⁿ⁻¹⁾ (T ⁽ⁿ⁻ ) in (step 6) ¹⁾ ), Σ _{kεS1∪Sn−1} r _k (T ⁽ⁿ⁻¹⁾ ), b _Sn is calculated in (Step 7) to (Step 9), and finally (Step 12) or (Step 13) has a function of determining whether or not a new call can be accepted.

(Example 6)
FIG. 14 is a diagram for explaining the operation of the network for realizing the call admission determination method according to the sixth embodiment of the present invention.
In FIG. 14, S is a service control device, TE is a user terminal device, UNI is a user network interface device, and NN is a network node. The numbers in the circles in the figure indicate the operation step numbers.
(Step 1) A connection request for a new call from the user terminal device TE is notified to the service control device S together with the priority class of the new call and token bucket parameter information.
(Step 2) The service control apparatus notifies the network node NN on the communication path of the new call of the priority class and token bucket parameter of the new call requesting connection.

(Step 3) Each network node NN determines whether or not the quality of each priority class can be guaranteed by receiving a new call (for example, using the method of the fourth embodiment), and determines whether or not the service can be accepted. S is notified.
(Step 4) The service control device S notifies the user terminal device TE and each network node NN of the final connection permission of the new call when the new call acceptance permission is obtained from all the network nodes NN (new). Call connection). If a connection rejection is notified from any of the network nodes NN, a new call is not accepted, so an acceptance rejection notification is sent to the user terminal device TE, and a communication end of the new call is notified to each network node NN ( Step 7).

(Step 5) When the call in communication is terminated, the end of the call is notified from the user terminal device TE to the service control device S.
(Step 6) The service control apparatus S notifies the network node NN on the communication path of the call of the end of communication of the call.
(Step 7) Each network node NN deletes information related to the call for which communication has ended (termination of communication).

  If the flow procedure in FIG. 12 and the operation procedure in FIG. 14 are respectively programmed and stored in a recording medium such as a CD-ROM, a general-purpose program can be used as a network program for realizing a quality assurance service using priority control. In addition, the program can be used for selling and lending programs via a Web server.

It is a figure which shows time passage of the maximum amount of the data transferred from the session flow prescribed | regulated with a token bucket. It is the figure which simulated a mode that the data transferred from the session flow prescribed | regulated with a token bucket added to a virtual buffer / trunk system. It is a figure which shows the time passage of the virtual buffer usage amount when the session flow prescribed | regulated with a token bucket is added to the virtual buffer / trunk system. It is a figure imitating a mode that a plurality of session flows prescribed by a token bucket are added to a virtual buffer / trunk system. It is the figure which modeled a mode that many session flows prescribed | regulated with a token bucket were added with respect to the node system which has an individual buffer corresponding to a some priority class. FIG. 5 is a diagram simulating that priority class 1 and 2 session flows are added to a single virtual buffer / trunk system. It is a table figure which shows the parameter of the traffic flow used in the Example of this invention. It is a figure which shows the time passage of the buffer usage amount for every priority class which concerns on Example 1 of this invention. It is a figure which shows the time passage of the buffer usage amount for every priority class which concerns on Example 2 of this invention. It is a figure which shows the time passage of the buffer usage amount for every priority class based on Example 3 of this invention. It is a figure which shows the time passage of the buffer usage amount for every priority class based on Example 4 of this invention. It is an operation | movement flowchart of the call admission determination method which concerns on Example 5 of this invention. It is a block diagram of the network node which implement | achieves the call admission determination method based on Example 5 of this invention. It is operation | movement explanatory drawing of the network which implement | achieves the call admission determination method based on Example 6 of this invention.

Explanation of symbols

1: Output interface 2: Individual buffer 3: Call information storage device 4: Quality calculation device 5: Signal control device S: Service control device TE: User terminal device NN: Network node UNI: User network interface device A (t): Maximum amount of traffic P: Peak rate T: Maximum length of time that traffic can be sent r: Transfer rate σ: Bucket size v (t): Used buffer amount at time t b: Maximum used buffer amount u (t): Time Use bandwidth of t c: Maximum available bandwidth B: Buffer bandwidth C: Link bandwidth c: Link bandwidth for session flow ρ: Token rate S: Aggregation T ⁽¹⁾ : From when data starts to accumulate in the buffer until it becomes empty Time b _{S1, S2} : Maximum buffer usage of priority classes 1 and 2

Claims (7)

A computer-controlled call admission determination method for quality assurance of multiple classes in an IP network,
The service control device activates the arithmetic circuit, forms a set with the priority class flow of the newly accepted call and the priority class flow having a higher priority than the priority class, and determines the virtual maximum buffer capacity,
By operating the arithmetic circuit, even for a class having a lower priority than the priority class, a set is composed of a flow of the class and a flow of a priority class having a higher priority than the class, as described above. Find the virtual maximum buffer capacity,
The service control device operates the arithmetic circuit to provide a priority class of a new reception call, a virtual maximum buffer capacity of each class having a lower priority than the priority class, and a buffer facility capacity provided for each class. And determining whether or not new acceptance is possible based on whether or not the virtual maximum buffer capacity of each class exceeds the buffer capacity. When the service control device represents the traffic characteristics of the session flow _i ∈ S in the token packet model of the peak rate P _i , the token rate ρ _i , and the burst size σ _i for the session flow set S by the operation of the arithmetic circuit. First, a bandwidth corresponding to the token rate is virtually allocated to each session flow, and the difference between the processing capacity of the node and the allocated virtual bandwidth is the burst duration t _i = σ _i / (P _i −ρ for each session flow. _i ) is calculated and allocated so that the virtual allocated bandwidth to the session having the longer burst duration corresponds to the peak rate, and the virtual bandwidth c _i allocated to the session flow i is calculate the buffer maximum value _{b i = t i (P i} -c i), by the entire session flow The virtual maximum buffer amount a call admission determination method of calculating at b = Σ _i∈S b _i,
The service control apparatus provides an individual buffer for each priority of the session flow, and ensures that data stored in a buffer with high priority is processed with priority over data stored in a buffer with low priority. Configure
By operating the arithmetic circuit, for a class having a high priority, the set S is configured only by a session flow corresponding to the class, and the virtual maximum buffer amount of the class is calculated.
A call admission determination method for a class having a low priority, comprising the set S by a session flow of the class and a class having a high priority, and calculating a virtual maximum buffer amount of the class. In the call admission determination method according to claim 2,
The service control device activates an arithmetic circuit at the time of a new call acceptance request, calculates a virtual maximum buffer amount of each class when a new call is included,
If the calculated virtual maximum buffer amount is less than or equal to the buffer amount installed in the node, the logical packet loss is regarded as zero and acceptance of a new call is permitted.
When the calculated virtual maximum buffer amount exceeds the buffer amount installed in the node, it is determined that the logical packet loss cannot be reduced to zero, and the new call acceptance is rejected. . In the call admission determination method according to claim 2,
The service control device operates an arithmetic circuit, calculates a virtual maximum buffer amount of a certain priority class, and first calculates a time until virtual buffers of all classes having a higher priority than the class become empty,
Compare the data flow rate of the class at the time of the above empty and the available bandwidth,
If the data flow rate of the class falls below the available bandwidth, calculate the arrival data amount of the class up to the point of time below, and the calculation result is the virtual maximum buffer amount,
A call admission determination method according to claim 2, wherein when the data flow rate of the class exceeds the available bandwidth, the virtual maximum buffer amount is set by the method according to claim 2. In the call admission determination method according to claim 4,
The service control device activates an arithmetic circuit at the time of a new call acceptance request, calculates a virtual maximum buffer amount of each class when a new call is included,
If the calculated virtual maximum buffer amount is less than or equal to the buffer amount installed in the node, the logical packet loss is regarded as zero and acceptance of a new call is permitted.
When the calculated virtual maximum buffer amount exceeds the buffer amount installed in the node, it is determined that the logical packet loss cannot be reduced to zero, and the new call acceptance is rejected. . In a network system that defines a session flow that flows into a service providing network based on IP or MPLS from a device in a user network by UNI, and provides quality assurance between UNIs,
For service control devices that connect to multiple network nodes, user terminal devices, and UNI devices to send and receive,
A plurality of individual buffer groups corresponding to the priority classes 1 to N and having different capacities,
Each session flow has a priority class, and the traffic characteristics of the session flow are expressed by a token bucket model using a peak rate, a token rate, and a burst size, so that each priority class at a forwarding node in the service providing network A quality calculation device for calculating the presence or absence of data loss,
Signal control for obtaining a connection request to the network node of the new call, notification parameters of the call, and notification of the termination of the connected call from the external signal line, and transmitting the result of the connection decision of the new call through the external signal line Equipment,
Stores information about the token bucket parameters and priority classes declared by each connected call, stores parameters declared from calls that require a new reception, and if a new call connection is refused and connected A network system, comprising: a call information storage device that deletes the parameter when an end notification of a completed call is transmitted to the signal control device. A call admission determination program for quality assurance of multiple classes in an IP network,
A procedure for activating the arithmetic circuit in the computer of the service control device, and forming a set of priority class flows of newly accepted calls and priority class flows having a higher priority than the priority class to determine the virtual maximum buffer capacity By operating the arithmetic circuit, even for a class having a lower priority than the priority class, a set is composed of the flow of the class and the priority class having a higher priority than the class in the same manner as described above. , A procedure for obtaining a virtual maximum buffer capacity, a priority class of a newly accepted call by operating the arithmetic circuit, a virtual maximum buffer capacity of each class having a lower priority than the priority class, and provided for each class Procedures for comparing the buffer capacity, and procedures for determining whether new acceptance is possible based on whether the virtual maximum buffer capacity of each class exceeds the buffer capacity , Call admission judgment program instructs.

Images