JP2000261431A - Method for managing variable band - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the quality control of virtual passes(VPs) and to obtain statistic multiple gain between VPs by newly storing a virtual channel(VC) in the VP of a variable bit rate on the basis of a 3rd evaluation expression or the like for evaluating whether the VC can be stored or not. SOLUTION: The sum of the sustainable cell rates(SCRs) of already set VCs, i.e., a parameter S1+... Sn, is calculated, the SCR of a certain VP is read out from a memory and the 3rd evaluation expression to be a comparing expression between the sum of the SCRs of VCs and the SCR of the VP is evaluated. When the 3rd evaluation expression is true, these VCs can be received by the VP 108, so that a connection setting request signal corresponding to a receivable signal is sent to an AT exchange 102 and the VCs are newly stored in the VP of a variable bit rate. Since whether the VCs can be stored in the VP or not is judged, the quality of the VPs can be managed and statistic multiple gain between plural VPs can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication method using ATM (Asynchronous Transfer Mode) and AAL2 (ATM adaptation layer 2).

[0002]

2. Description of the Related Art In an ATM for transmitting various information in fixed-length blocks called cells, prior to connection setting,
The traffic descriptor describes the traffic characteristics. The ATM switch accepts the connection based on this, determines whether the existing connection and the connection satisfy predetermined quality, and accepts the connection only when satisfied. This is called connection admission control (CAC).

[0003] Traffic descriptors include PCR (peak cell rate), SCR (sustainable cell rate), and MB.
It consists of parameters such as S (maximum burst size). In particular, PCR is used in an ATM layer service class called CBR (Continuous Bit Rate). Similarly, V
In an ATM layer service class called BR (variable bit rate), PCR, SCR and MBS are used.

In an ATM network, as shown in FIG. 9, a transmission path 901 is a VP (virtual path) 902 which is a logical path.
Can be used separately. Similarly, VP9
02 is a logical channel VC (virtual channel)
903 can be accommodated. A for VP connection
Since it is one of the TM connections, types such as CBR and VBR are conceivable. In the case of a CBR VP (hereinafter referred to as CBR-VP as necessary. The same applies to a VBR), it is possible to control the acceptance of a VC connection by making the VP the same as a transmission path. Regarding the admission control for the VBR VC connection, see "Hiro
shi Saito, Teletraffic Technologies in ATM Network
s, Artech House, Boston, 1995 "and" Reference 2 "" Supervised by Aoki, Aoyama and Minuma, Broadband ISDN and ATM Technology, IEICE ", etc. On the other hand, in the VBR-VP, the VC of the VBR (hereinafter referred to as VBR-
Notated as VC. The same applies to the case of CBR. ) Has not yet been sufficiently studied on how to determine whether the predetermined quality is satisfied.

Recently, AA which uses one VC connection with a plurality of information sources (particularly low bit rate voice) is used.
An ATM adaptation layer called L2 was developed. Here, since one VC is used for a plurality of AAL2 connections, it is necessary to determine whether or not an AAL2 connection setting request is accepted based on the traffic descriptor of the AAL2 connection. Although the traffic descriptor of the AAL2 connection is not standardized, it is considered to be the same or similar to the traffic descriptor of the ATM connection. CBR and VBR are considered as VCs that accept the AAL2 connection. Regarding the problem of "how many AAL2 connections are inserted into the CBR-VC when the low bit rate voice uses the AAL2 connection, the quality such as the cell loss rate deteriorates" Hiroshi Saito, Performance evaluation of AAL2 switching network, IEICE Technical Report, IN98-117 (1
998) ”and“ Reference 4 ”“ Yoshi Saito, Performance Evaluation of AAL2CLAD, IEICE Technical Report, CS98-112 (1998) ”.

[0006]

As described above, the admission control when setting the AAL2 connection in the VC,
When C is a VBR, an important issue to be addressed is how to determine whether to accept the AAL2 connection setting request and perform appropriate bandwidth management. Similarly, when there is a VBR-VC connection setting request to the VBR-VP, it is an important study topic how to perform appropriate bandwidth management if the reception is determined.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a variable band management method capable of performing appropriate band management in variable band communication using ATM. .

[0008]

In order to achieve the above object, according to the present invention, a variable bit rate (VBR:
Variable Bit Rate) virtual channel (VC: Virtual C)
hannel) and an asynchronous transfer mode (ATM: Asynchrnous Transfer M) that provides a virtual path (VP).
ode) In the network, a virtual path having a variable bit rate is accommodated in a transmission path based on a first evaluation formula determined in advance, a traffic descriptor of a virtual channel already accommodated in the virtual path, and a newly accommodated virtual path. The traffic descriptor of the channel and the peak cell rate of the virtual path (PCR:
A second evaluation expression for evaluating whether a virtual channel can be accommodated based on the peak cell rate, a traffic descriptor of a virtual channel already accommodated in the virtual path, a traffic descriptor of a newly accommodated virtual channel, and the virtual path. Sustainable CellRat (SCR)
e) based on a third evaluation expression for evaluating whether or not the virtual channel can be accommodated based on e), if both the evaluation results of the second and third evaluation expressions are acceptable, the virtual path of the variable bit rate Proposes a variable bandwidth management method characterized by accommodating a new virtual channel.

According to the present invention, it is determined whether or not a virtual channel with a variable bit rate can accommodate a virtual channel based on various traffic descriptors of the virtual channel and the peak cell rate and the sustainable rate of the virtual path. As a result, the quality of the virtual path can be managed, and a statistical multiplex gain between the virtual paths can be obtained.

[0010] As a preferred embodiment of the present invention, in the variable bandwidth management method according to the first aspect of the present invention, the third evaluation formula is a virtual channel already accommodated in the virtual path. In addition, the present invention proposes that a new virtual channel can be accommodated when the sum of the sustainable rates of the newly accommodated virtual channels is equal to or less than the sustainable rate of the virtual path.

According to a third aspect of the present invention, in the variable bandwidth management method according to the first aspect, the first evaluation expression is an evaluation expression using a peak cell rate and a sustainable cell rate of each virtual path in the transmission path. We propose one that is characterized.

Further, according to the invention of claim 4, AAL2
In an ATM network that provides a connection of (ATM Adaptation Layer 2), based on a fourth evaluation formula using a peak cell rate of a virtual channel, a maximum value in the virtual channel that satisfies a predetermined quality corresponding to the peak cell rate is satisfied. A
The number of AL connections is determined in advance, and AA is set in the virtual channel.
When the L2 connection is set, if the virtual channel has a continuous bit rate (CBR: Constant Bit Rate), the AAL already set in the virtual channel is set.
When the number of 2 connections is smaller than the maximum number of AAL connections corresponding to the peak cell rate of the virtual channel, it is determined that the setting of the AAL2 connection is accepted. If the virtual channel has a variable bit rate, The number of already set AAL2 connections is smaller than the maximum number of AAL connections corresponding to the peak cell rate of the virtual channel, and the value of the number of AAL2 connections + 1 is determined by a predetermined fifth evaluation formula. A variable bandwidth management method is proposed in which it is determined that an AAL2 connection setting is accepted when an evaluation result is acceptable.

According to the present invention, the peak cell rate of the virtual channel and the AAL already set in the virtual channel
Based on the number of 2 connections and the maximum number of AAL connections that can be accommodated, it is determined whether an AAL2 connection to a variable channel can be set. Thereby, the quality of the AAL2 connection can be managed. In particular, when the virtual path has a variable bit rate, statistical multiplex gain between virtual channels can be obtained.

As a preferred embodiment of the present invention, in the invention according to claim 5, in the variable bandwidth management method according to claim 4, the fourth evaluation expression uses the number of AAL connections and the peak cell rate of a virtual channel. We propose a method that is characterized by an evaluation formula.

According to a sixth aspect of the present invention, in the variable bandwidth management method according to the fourth aspect, the fifth evaluation expression is AA
The present invention proposes a method characterized in that when the average cell rate corresponding to the number of L2 connections is equal to or less than the sustainable cell rate of the virtual channel, the cell rate is evaluated as acceptable.

According to a seventh aspect of the present invention, in the variable bandwidth management method according to the fourth aspect, when the setting of the AAL2 connection cannot be accepted, the AA is set.
It is characterized by making a decision not to accept the L2 connection, or by setting a new virtual channel or changing the peak cell rate of the virtual channel and again making an acceptance decision of the AAL2 connection on the new or changed virtual channel. I suggest something.

According to the invention of claim 8, in the ATM network providing the AAL2 connection, if it is impossible to determine whether to accept the setting of a new AAL2 connection in the already set virtual channel, a new virtual network is established. A variable bandwidth management method is proposed in which a channel is set or a parameter of the virtual channel that has already been set is changed.

Further, in the ninth aspect of the present invention, the fourth to fourth aspects of the present invention are described.
8. The variable bandwidth management method according to claim 8, wherein the virtual channel is a virtual channel of a variable bit rate, and is virtual based on an evaluation formula using a peak cell rate and a sustainable cell rate of each virtual channel of the variable bit rate. A feature is proposed in which accommodation in a path has been determined.

Further, according to the tenth aspect, in the eighth aspect,
10. In the variable bandwidth management method according to any one of 9 to 9, when setting the new virtual channel or changing parameters of the virtual channel, the peak cell rate and the sustainable rate of the virtual channel of each variable bit rate are used. Based on the evaluation formula, a proposal is made of determining whether or not the setting or change is possible.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a variable bandwidth management method according to a first embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a configuration diagram of a network, and FIG. 2 is a configuration diagram of an ATM exchange.

In the network according to the present embodiment, as shown in FIG. 1, the ATM switch 10 is connected to transmission paths 105, 106 and 107 via a VP cross connector 104.
1, 102 and 103 are connected. ATM switch 1
Terminals 111 to 114 are connected to 01, terminals 115 to 118 are connected to the ATM switch 102, and terminals 119 to 122 are connected to the ATM switch 103, respectively. Each transmission path 105 accommodates one or more VBR-VPs (variable bit rate VPs). In the present embodiment, this V
VC of VBR- (V of variable bit rate) in BR-VP
The case of accepting C) will be described.

It is assumed that the VP is set at the time of design based on a reception judgment described later, and is not set on demand. In the case of on-demand, it can be easily analogized and implemented from the present embodiment. Here, the transmission path speed is C (cells / second), the buffer size is K (cells), and the PCR (peak cell rate) and SCR (sustainable cell rate) of the i-th VP in the transmission path are respectively Let P _i and S _i . Further, it is assumed that the (n-1) th VP has already been received in the transmission path.

Whether VBR-VP is accommodated in the transmission path is determined based on the following first evaluation formula. This first
The evaluation expression is composed of two expressions, a VBR evaluation expression shown in [Equation 1] and a peak allocation evaluation expression shown in [Equation 2].
When at least one of the VBR evaluation formula shown in [Equation 1] and the peak allocation evaluation formula shown in [Equation 2] is satisfied, it is determined that the data can be accommodated. Note that CLR is the cell loss rate (Cell Loss
Rattion) is a parameter indicating service quality.

[0024]

(Equation 1)

[0025]

(Equation 2)

By using such a judgment, FIG.
In the network of FIG.
109, VPs 108 and 110 in the transmission path 106,
It is assumed that VPs 109 and 110 are set in the transmission path 107 at the time of design.

As shown in FIG. 2, the ATM switch 101 includes line input sections 201 and 202 connected to each terminal, a switch section 203 for switching ATM cells from the line input sections 201 and 202, and a buffer for the ATM cells. Buffer units 205 and 206 for each VP to be ringed, and line output unit 2
07, 208 and a processor 204 as an arithmetic unit.

Hereinafter, the terminal 111 is connected to the terminal 115 by V
The case of setting the VC connection of BR will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart for explaining the operation of the ATM exchange when setting the VC connection.

The setting of the VC connection is started when the terminal 111 issues a connection setting request to the ATM switch 101. That is, the setting request signal enters the line input unit 201 as shown in FIG. In the line input unit 201, physical layer processing and the like are performed, and the result is sent to the processor 204 by the switch unit 203. In response to the setting request signal, the processor 204 performs the following processing to perform reception control for determining whether the VC for which the setting request has been made in the VP 108 can be set. The VP 108 includes, for example, the terminal 112-1.
It is assumed that there are (n-1) existing VC connections, such as 16 VC connections (not shown).

First, the VP is stored in the memory of the processor 204.
Read the PCR buffer size and VP108 another buffer portion 205, respectively K 'and the P ₁ (step S301). Next, regarding the existing (n-1) VC connections, the PCR and SCR of the iVC are read from the memory in the processor, and p _i and s _i (i = 1,
, N-1) (step S302).

Next, the PCR and SC of the VC making the setting request
R for p_n, S_nAnd the second evaluation expression similar to the VP reception control
The evaluation using is performed. Here, the second evaluation expression is represented by [Equation 1].
Are different from the evaluation function CLR described in (K ′,
P₁; P₁, S₁;…; P_n, S _n) To [Equation 3]
VBR evaluation formula shown and peak allocation evaluation formula shown in [Equation 4]
The accommodation availability is determined by the VBR evaluation formula shown in [Equation 3]
At least one of the peak allocation evaluation formulas shown in [Equation 4]
When it is satisfied, it is determined that accommodation is possible.

[0032]

(Equation 3)

[0033]

(Equation 4)

Specifically, first, the evaluation function CLR described in the above [Equation 1] is converted into different parameters (K ′, P ₁ ; p ₁ ,
s ₁ ;...; _pn , s _n ) and the peak assignment evaluation formula shown in the above [Equation 4] (step S).
303).

Next, a predetermined cell loss rate target value is read from the memory (step S304), and this is compared with the calculation result of the evaluation function CLR, and the peak allocation evaluation formula is evaluated (step S305). That is,
In step S305, the evaluation evaluation of the second evaluation expression is performed.

If the second evaluation expression is true, that is, if the peak allocation evaluation expression of [Equation 4] is true, or if the calculated value of the evaluation function CLR is equal to or less than the target value (that is, the VBR of [Equation 3])
If the evaluation expression is true), evaluation is performed using the third evaluation expression shown in [Equation 5].

[0037]

(Equation 5)

More specifically, first, the sum of the existing VC and the SCR of the VC, s ₁ +... S _n is calculated (step S 30).
6) Further, the VP SCR is read from the memory (Step S307), and the sum of the VC SCR and the VP SC is read.
Evaluate a third evaluation expression that is a comparison expression with R (step S
308).

If the third evaluation expression is true, that is, if the sum of the SCRs of the VC is equal to or less than the SCR of the VP,
Since the VC can be accepted by the VP 108, a connection setting request signal corresponding to the acceptability signal is sent to the ATM switch 102, and the information of the existing VC is used as the information of the existing VC.
Write CR and SCR to memory (step S30)
9).

On the other hand, if the second evaluation expression is not true, that is, if the peak allocation evaluation expression is false and the evaluation function C
If the LR calculation exceeds the cell loss target, and
If the third evaluation formula is not true, that is, if the sum of the existing VC and the SCR of the VC exceeds the SCR of the VP, the VC is rejected and a disconnection signal, which is a rejection signal, is sent to the terminal 111. (Step 310).

In this way, the acceptability is determined and the AT
The reception control in the M exchange 101 ends. Each signal is sent from the processor 204 to the destination via an appropriate VP-specific buffer unit and line output unit determined for each destination via the switch unit 203. The ATM switch 102 issues a connection setting request to the terminal 115 in the same procedure as the ATM switch 101. When the terminal 115 responds, a response signal is notified to the terminal 111 via the ATM switches 102 and 101, and a connection is established.

The connection is released by the terminal 111 sending a release request signal to the ATM switch 101.
Similarly to the setting request signal, the release request signal reaches the processor 204 in the ATM switch 101. Processor 204
Determines that the request is a release request, and determines the PCR of the existing VC,
The PCR and SCR for the VC are deleted from the SCR. Thereafter, a release request signal is sent to the ATM switch 102 in the same manner as the setting request signal. The ATM switch 102 also sends a release request to the terminal 115 after processing similar to that of the ATM switch 101. As described above, the terminal 111 and the terminal 1
The connection between 15 is released.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
Variable bandwidth management method according to the embodiment of FIG.
This will be described with reference to FIG. FIG. 4 is a network configuration diagram,
FIG. 5 is a configuration diagram of the AAL2 end system, and FIGS. 6 and 7.
FIG. 4 is a diagram illustrating information stored in the AAL2 end system.

Here, a case will be described in which a VC of VBR (or CBR) is present in a VP of CBR and an AAL2 connection is received therein. Note that V
The description of the BR VP is omitted here because it can be easily analogized. For simplicity, it is assumed that the VP is set at the time of design.

Although the VC is also set at the time of design, a case where the VC is changed on demand will be described later. VC satisfies the following design conditions. Within CBR-VP with output buffer size K and PCR = C, P
CR and SCR are VBR−VC of P _i and S _i , respectively (i =
1,..., N) are multiplexed, these VCs are designed to satisfy the VBR evaluation formula or the peak allocation evaluation formula shown in the first embodiment.

First, the network shown in FIG. 4 will be described. The information sources 401 to 408 are information sources such as audio.
Generally, a plurality of information sources are accommodated in one AAL2 end system 409-412. The AAL2 end systems 409 to 412 operate as (an aggregate of) ATM terminals as viewed from the ATM network. The VC connection is set between the AAL2 end systems in FIG. AT
The M exchanges 413 and 414 are the ATMs shown in FIGS.
It is equivalent to the exchange 101.

Next, the configuration of the AAL2 end system 409 is shown in FIG. The signals from the information sources 401 to 402 are
Headers and the like are added by the CPS packet devices 501 to 504 according to a packet format called a CPS packet, and thereby a CPS packet is generated. Normal,
A CPS packet is supplied from a plurality of CPS packet devices to the cell forming device 505 or 506, a cell header or the like is added, and a cell is assembled for each VC. Normal,
In this process, a timeout is set. The generated cells wait for transmission in the cell transmission queues 507 and 508 for each VC. From the cell transmission queue, a cell is taken out according to the PCR of the VC, subjected to physical layer processing and the like by an outgoing line device, and transmitted from the outgoing line. AAL2 on the receiving side
The end system takes the reverse procedure. That is,
After the processing of the physical layer or the like, the cells are divided into VP and VC, and the cells are decomposed by the cell forming apparatus to become CPS packets. A CPS packet is a CPS determined by header information.
The packet is sent to the packetizer, and the header and the like are removed and sent to the receiving source.

By the way, in Reference 3 or Reference 4, P
For the VC of CBR when CR is P, the speech coding rate, timeout and the sending queue size of VC, A
An equation for calculating the cell loss rate CLR (P, x) in the VC transmission queue when the number x of AL2 connections is given is shown. In the present invention, this is used to determine the CLR for each P.
(P, x) <maximum x that satisfies the target value of the cell loss rate in the cell transmission queue, that is, a table (FIG. 6) of the maximum number x of AAL2 connections that can be accommodated under the target quality (FIG. 6) is stored in the processor 511. Suppose In references 3 and 4,
An expression for calculating the average cell rate generated by the cellifying devices 505 and 506 when the audio coding rate, the timeout, and the number x of AAL2 connections are given is shown.
When VBR-VC is used, the table of FIG. 7 including this average cell rate in addition to FIG.
It is assumed that the information is stored in No. 1.

Hereinafter, the terminal 401 to the terminal 405 in FIG.
The procedure for setting the AAL2 connection to the server will be described with reference to the flowchart in FIG. FIG. 8 is a flowchart illustrating a procedure for setting an AAL2 connection in a VC.

First, a call signal from the terminal 401, which is an information source, is received by the signal receiving device 512 in the AAL2 end system 409 (step S801). The received call signal is sent to the processor 511,
At 11, it is specified that the signal is a call signal and the destination terminal 405 is specified (step S802).

The processor 511 determines from the destination terminal number that an AAL2 connection for the call is to be set in the VC set between the AAL2 end systems 409 and 411 (step S803), and determines whether an AAL2 connection is accepted for the VC. Is performed (step S804).

First, the processor 511 holds
The number of AAL connections x 'already set in the VC and the PCR (P) of the VC are read (steps S805 and S806). Next, with reference to the table of FIG. 6 held in the processor 511, the maximum number x of AAL2 connections that can be accommodated for P is read (step S807).

Next, the number of existing AAL connections x 'in the VC is compared with the maximum number of AAL2 connections x that can be accommodated (step S808). If x' is equal to or larger than x, the AAL2 connection to the VC is accepted. Is determined to be impossible (step S813). If x 'is small, in the case of CBR-VC, it is determined that it can be accepted (step S809). If x 'is small and VBR-VC, the following conditions are further checked.

First, the SCR of the relevant VC stored in the processor 511 is read (step S810). The average cell rate corresponding to the number of existing AAL connections x '+ 1 is read with reference to the table of FIG. 7 held in the processor 511 (step S811). If the average cell rate is equal to or less than the SCR, the same AAL2 connection is accepted by the VC (step S809). SCR
If the number exceeds the threshold, the request is not accepted (step S813).
If not accepted, the processor 511 sends a disconnection signal to the terminal 401 via the signal transmission / reception device 512 (step S814). If accepted, the number of AAL2 connections of the VC held in the processor 511 is increased by 1 (step S815).

Next, AAL which is the opposite end point of the VC
A call signal is sent to the two end system 411 (step S816). At this time, the ATM switch 413 on the way,
414 relays only the AAL2 call signal and delivers it to the AAL2 end system 411, and does not perform other processing. AAL2 end system 41 that received this signal
1 is to solve the signal type and the destination in the processor,
While calling the destination terminal 405, the calling terminal 401
Then, a call arrival signal is transmitted through the AAL2 end system 409 (step S817).

In the AAL2 end systems 409 and 411, the processor initializes the CPS packetizer (memory clear and assigns a channel ID, etc.) in preparation for the response of the sending and receiving terminals and information transmission / reception (step S818). AA receiving the response signal of the called terminal 405 from the signal transmitting / receiving device
The L2 end system 411 sends the same signal to the calling terminal 401 via the AAL2 end system 409 (Step S819). Thereby, communication between both terminals is started (step S820). Here, the information from both terminals is
As described at the beginning of this embodiment,
The cell is sent in the form of a cell, and the cell is again converted into a CPS packet to extract information.

When the information transmission / reception is completed (step S82)
1) The calling terminal 401, which is the information source, sends the AAL
It is sent to the two-end system 409 (step S822).
When the AAL2 end system 409 receives the same signal from the signal transmission / reception device, the processor interprets the signal type and the destination, specifies the AAL2 connection and VC based on the interpreted information, and converts the AAL2 connection into a CPS packet corresponding to the AAL2 connection. The device 605 is released (step S823). Also, the AAL2 end system 409
The “number of AAL2 connections set for the VC” held in the processor 511 is reduced by one (step S824). Then, AAL2 end system 41
When the end signal is transferred to the AAL2 end system 4
11 receives the end signal (step S825).
Upon receiving the signal, the AAL2 end system 411 interprets the signal type and the destination, specifies the corresponding VC and AAL2 connection, and releases the corresponding CPS packetizer (step S826). Thereafter, a disconnection signal is transmitted to the destination terminal 405, which is an information source, and the terminal 405 receives the signal (step S827).

Next, a case where a VC is set or a parameter of the VC is changed on demand will be described. This is because when the reception is disabled in step S813 of FIG. 8, the setting of a new VC or the parameter (PC
R or SCR).

In this case, first, the AAL2 end system 409 determines whether a new VC can be set based on the VBR evaluation formula and the peak allocation evaluation formula described as the VC design conditions of the present embodiment. Alternatively, whether the new parameter PCR / SCR is possible is determined by the same evaluation formula. If not possible, a disconnection signal is transmitted to the terminal 401.

Next, the AAL2 end system 409
A signal is sent to the ATM switch 413 to set a new VC connection between the AAL2 end systems 409-411 or to change the PCR / SCR of the VC. The ATM switch 413, which has received the signal,
Using the above evaluation formula, it is determined whether a new VC can be set or a parameter can be changed. If it is not possible, the ATM exchange 413 sends a disconnection signal or a parameter change disable to the AAL2 end system 409, and the AAL2 end system 409 receives the transmission and sends a disconnection signal to the terminal 401. If the reception is possible or the parameter can be changed, the same procedure is performed in the ATM exchange 414. Finally AAL2 end system 409
-411 is notified of it. The AAL2 end system 409 receives the signal, and starts accepting the AAL2 connection for the new VC or the parameter update VC again (step S804).

[0061]

As described in detail above, according to the present invention,
Based on various traffic descriptors of virtual channel and peak cell rate and sustainable rate of virtual path,
It is determined whether or not a virtual channel can be accommodated in a virtual path with a variable bit rate. As a result, the quality of the virtual path can be managed, and a statistical multiplex gain between the virtual paths can be obtained.

Further, according to the present invention, it is determined whether an AAL2 connection to a variable channel can be set based on the peak cell rate of the virtual channel, the number of AAL2 connections in the virtual channel, and the average cell rate of the AAL2 connections. Thereby, the quality of the AAL2 connection can be managed. In particular, when the virtual path has a variable bit rate, statistical multiplex gain between virtual channels can be obtained.

[Brief description of the drawings]

FIG. 1 is a network configuration diagram

FIG. 2 is a configuration diagram of an ATM switch;

FIG. 3 is a flowchart for explaining the operation of the ATM exchange when setting a VC connection;

FIG. 4 is a network configuration diagram.

FIG. 5 is a configuration diagram of an AAL2 end system.

FIG. 6 is a view for explaining information stored in the AAL2 end system.

FIG. 7 is a view for explaining information stored in the AAL2 end system.

FIG. 8 is a flowchart illustrating a procedure for setting an AAL2 connection in a VC.

FIG. 9 is a conceptual diagram of an ATM network.

[Explanation of symbols]

101 to 103: ATM switch, 104: VP cross connector, 105 to 107: Transmission path, 108 to 110
... VP, 111-122 ... terminals, 201, 202 ... line input unit, 203 ... switch unit, 204 ... processor, 2
05, 206: VP-based buffer unit, 207, 208: line output unit, 401 to 408: information source, 409 to 412:
AAL2 end system, 413,414 ... ATM switch, 501-504 ... CPS packetizer, 505
506: Cellular device, 507, 508: Cell sending queue, 509: VP buffer, 510: Outgoing line device, 5
11 Processor, 512 Signal transmission / reception device

Claims (10)

[Claims] 1. A variable bit rate (VBR: Variable B)
In an Asynchronous Transfer Mode (ATM) network that provides a virtual channel (VC: Virtual Channel) and a virtual path (VP: Virtual Path) of a variable rate, a virtual path of a variable bit rate is determined by a first predetermined virtual path. A traffic descriptor of a virtual channel already accommodated in the virtual path, a traffic descriptor of a newly accommodated virtual channel, and a peak cell rate (PC
R: Peak Cell Rate), a second evaluation formula for evaluating whether a virtual channel can be accommodated, a traffic descriptor of a virtual channel already accommodated in the virtual path, a traffic descriptor of a newly accommodated virtual channel, and Sustainable Cell Rate (SCR: Virtual Path)
Rate), the virtual path of the variable bit rate is determined when both of the second and third evaluation expressions are accommodable based on the third evaluation expression for evaluating whether or not the virtual channel can be accommodated. A variable bandwidth management method characterized by accommodating a new virtual channel. 2. The method according to claim 1, wherein the sum of the sustainable rates of the virtual channels already accommodated in the virtual path and the newly accommodated virtual channel is less than or equal to the sustainable rate of the virtual path. The variable bandwidth management method according to claim 1, wherein accommodating of a virtual channel is enabled. 3. The evaluation formula according to claim 1, wherein the first evaluation formula is an evaluation formula using a peak cell rate and a sustainable cell rate of each virtual path in the transmission path.
The variable bandwidth management method described in the above. 4. In an ATM network providing an AAL2 (ATM Adaptation Layer 2) connection, a predetermined quality is satisfied corresponding to the peak cell rate based on a fourth evaluation formula using the peak cell rate of a virtual channel. When the maximum number of AAL connections in the virtual channel is obtained in advance and an AAL2 connection is set in the virtual channel, the virtual channel is set to a continuous bit rate (CBR:
nt Bit Rate), when the number of AAL2 connections already set in the virtual channel is smaller than the maximum number of AAL connections corresponding to the peak cell rate of the virtual channel, it is determined that the setting of the AAL2 connection is accepted. When the virtual channel has a variable bit rate, the number of AAL2 connections already set in the virtual channel is smaller than the maximum number of AAL connections corresponding to the peak cell rate of the virtual channel, and When the evaluation result of the predetermined fifth evaluation expression is acceptable for the value of the number of connections + 1, AA
A variable bandwidth management method, comprising: determining to accept setting of an L2 connection. 5. The variable bandwidth management method according to claim 4, wherein the fourth evaluation expression is an evaluation expression using the number of AAL connections and a peak cell rate of a virtual channel. 6. The variable bandwidth according to claim 4, wherein the fifth evaluation expression evaluates that the average cell rate corresponding to the number of AAL2 connections is acceptable when the average cell rate is equal to or less than the sustainable cell rate of the virtual channel. Management method. 7. When the setting of the AAL2 connection cannot be accepted, it is determined that the AAL2 connection is not accepted, or a new virtual channel is set or the peak cell rate of the virtual channel is changed. AAL again with new or changed virtual channel
5. The variable bandwidth management method according to claim 4, wherein two connection acceptance determinations are performed. 8. An ATM providing an AAL2 connection.
In the network, a new AAL2 into a virtual channel that has already been set up
A variable bandwidth management method comprising: setting a new virtual channel or changing a parameter of the virtual channel that has already been set, when it is impossible to determine whether to accept a connection. 9. The virtual channel is a virtual channel of a variable bit rate, and accommodation to the virtual path is determined based on an evaluation formula using a peak cell rate and a sustainable cell rate of the virtual channel of each variable bit rate. The variable bandwidth management method according to any one of claims 4 to 8, wherein: 10. When setting a new virtual channel or changing a parameter of a virtual channel, the setting or changing is performed based on an evaluation formula using a peak cell rate and a sustainable rate of the virtual channel of each variable bit rate. 10. The variable bandwidth management method according to claim 8, wherein the determination is made as to whether the variable bandwidth management is possible.