JPH09107364A - Adaptive transmission rate control communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an available band width while satisfying impartiality of a transmission rate by providing a means collecting and storing various information and a means calculating an acceptable transmission rate based on the stored information to the communication equipment. SOLUTION: Terminal equipments 11 and 21, 12 and 22, 13 and 33 are connected by connectors 41-43 via exchanges 31-33 interconnected by transmission lines 51, 52. Then information is sent/received at a variable transmission rate. Each of the exchanges 31-33 is provided with an exchange section 301 making line exchange, and a control section 302 controlling the exchange section 301 and collecting various information such as notice of information relating a receptible transmission rate of contained connections 41-43 to caller terminal equipments 11-13. Furthermore, each of the exchanges 31-33 is provided with a storage section 303 storing information collected by the section 302 and an arithmetic section 304 calculating a transmission rate for each connection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet switching network or an asynchronous transfer mode (ATM: Asynchronous Trannsf).
er Mode) for rate control and traffic control in networks.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional packet network or ATM.
It is a figure explaining rate control in a network. here,
The terminals 611 to 613 are calling terminals, and the exchanges 631 to 6 are provided between the terminals 621 to 623, which are destination terminals.
Connections 641, 642, and 643 passing through 33 are set up. These connections 641, 6
42 and 643 are transmission lines 65 between the exchanges 631 to 633.
Shared use of 1,652. Rate control is performed as follows. That is, the terminal 611 to be the calling terminal
613 generates and inserts a control cell at fixed cell intervals, reciprocates the control cell between terminals 621 to 623, which are destination terminals, and exchanges 631 to 633 write information in the cell and issue a call. The terminals 611 to 613, which are terminals, perform rate control with reference to the terminals.

For example, ATM Forum specifications (95-0013R
2, 94-0983, 95-0195 etc.) ABR (Available Bi
In the rate control used in the (t Rate) protocol, the transmission rate of each connection is controlled fairly so that congestion does not occur in accordance with the available bandwidth of the shared route and the requested bandwidth, so that the calling terminal is A control cell is transmitted at each cell interval, and each exchange passing through the control cell reads the allowable transmission rate of the terminal from the control cell and calculates congestion information for the exchange itself and an acceptable transmission rate.
In the control cell, the maximum value (PCR) that the allowable transmission rate can take in each connection is written as the initial value of the transmission rate that can be accepted when the calling terminal transmits. Each exchange writes the calculated rate in the control cell and sends it to the calling terminal only when the acceptable transmission rate calculated by the exchange is smaller than the acceptable transmission rate written in the returned control cell. Notice. The calling terminal sets its own allowed transmission rate (ACR: Allowed Cell Rate) below the notified acceptable transmission rate, and transmits at a rate below the ACR.

FIGS. 7 to 9 are diagrams showing the flow of control in the exchange, and FIG. 7 shows the control when it is judged as congestion,
FIG. 8 shows control when a control cell arrives from the calling terminal side,
FIG. 9 shows the control when the control cell is returned from the destination terminal side. Each exchange observes the queue length in the transmission waiting cell buffer and determines that its own exchange is congested when the queue exceeds the threshold value, and determines that it is not congested otherwise. Then, when it is determined that there is a congestion state, a value obtained by subtracting the current allowable transmission rate at a constant rate is calculated as an acceptable transmission rate for the exchange.

J-th connection (j = 1, 2, ...,
n), the M related to the connection
E obtained by multiplying ACR _j by a constant ERD smaller than 1
Let RQ _j be an acceptable transmission rate. Then, when the control cell from the calling terminal arrives, ccr is compared with the current allowable transmission rate ccr _j written in the control cell.
_j × min (1, R ₀ / rate _j ) is obtained and this is set as a new allowable transmission rate ccr _j . From this new allowable transmission rate ccr _j , MACR _j + (ccr _j −MAC
R _j ) × AVF is obtained and set as a new MACR _j . However, R ₀ and AVF are constants, and rate _j is the actual transmission rate obtained from the current observation of the j-th connection. The switch and the control cells comes folded, with reference to the field value ER _c for notifying an acceptable transmission cell rate on the control cell, ERQ _j <ER if _c of the control cell ER _c To ERQ _j ,
If ERQ _j ≧ ER _c , the control cell is relayed to the calling terminal as it is.

[0006] Since the terminal sets the ACR below the notified acceptable transmission rate, as a result, the allowable transmission rate (ACR) decreases.

FIG. 10 shows the flow of control of the exchange when it is determined that there is no congestion. When it is determined that the exchange is not congested, the exchange increases the acceptable transmission rate of the exchange above the allowable transmission rate. That is, 1-rate _j / R ₀ is multiplied by a constant Gain to obtain 1
Was the ERX _j a plus, this as a new ERQ _j those by multiplying the ERQ _j, the ERQ _j and MACR
The smallest one of _j × ERU and R ₀ is set as a new ERQ _j, and the large one of ERQ _j and MACR _j × ERD is set as a new ERQ _j . The control is the same when the control cell arrives from the calling terminal side and when the control cell is returned from the called terminal side.
CR increases.

[0008]

In the prior art, the acceptable transmission rate is increased or decreased for the connections on the same switch based on the same congestion state. For this reason, the control is to perform a uniform operation of increasing or decreasing as a whole, and does not necessarily improve fairness.

The present invention solves such a problem, and changes the direction in which the available bandwidth of each connection is increased as much as possible while satisfying the fairness of the acceptable transmission rate notified between the connections. An object of the present invention is to provide an adaptive transmission rate control communication device that can be used.

[0010]

An adaptive transmission rate control communication device according to the present invention is, for a plurality of connections accommodated in an exchange and sharing a transmission line, an allowable transmission rate and an actual transmission rate allowed for each connection, Collects and retains information about the total bandwidth and total input bandwidth of the shared transmission path, and the number of connections that share the transmission path, and based on this information, notifies the originating terminal of acceptable transmission. The feature is that the rate is calculated for each connection.

As a result, the acceptable transmission rate to be notified between the respective connections is not individually directed to the same direction such as increasing or decreasing but is rewritten and notified individually in the direction of increasing fairness. You can In addition, the acceptable transmission rate for each connection can be rewritten and notified in the direction of increasing the usable bandwidth of each connection within the range where congestion does not occur.

It is also possible to notify the originating terminal of the acceptable transmission rate only by the exchange that accommodates the originating terminal.
In this case, the exchange directly accommodating the terminal on the originating side, for a plurality of connections sharing the route with the connection that the accommodating terminal is the originating terminal, and the allowable transmission rate and actual Based on the information held by the means for collecting and holding information on the transmission rate, the bandwidth of the shared route and the total input bandwidth, and the number of connections sharing the route. Means for calculating an acceptable transmission rate notified by the notification means for each connection may be provided.

In this case, the load required for the generation and notification of the control information in the exchange in the communication network is reduced, and when there is a change in the transmission rate of each connection, an acceptable transmission rate corresponding to the change is set. The time required for calculation is short, the notification to the calling terminal can be performed at high speed, and it is possible to calculate only the subscriber exchange without calculating the transmission rate that can be accepted by all exchanges. The rate can be immediately controlled even when the transmission starts.

The information notified by the notifying means to the terminal may be the data of the transmission rate itself, or the information for instructing the increase or decrease of the allowable transmission rate. When the latter information is used, the terminal increases or decreases its own allowable transmission rate according to a predetermined calculation formula.

In the above configuration, the calculating means is the variance V ({ccr ₁ , ccr ₂ , ..., Ccr _n }, {r ₁ , r ₂ , ..., Of the ratio of the allowable transmission rate to the request rate of each connection. r _n }) ＝ (1 /
n) Σ _j (ccr _j / r _j − (1 / n) Σ _i ccr _i / r _i ) ² as an evaluation function, ERQ _j = ccr _j −α _j · sign {n · ccr _j / r _j −w・ Σ _i ccr / r
_i }, it is preferable to include a calculating unit for obtaining the transmission rate ERG _j that can be accepted by the exchange for the connection j (j = 1, 2, ..., N). However, Σ _i , Σ _j
Is the sum of i and j = 1 to n, ccr _j and r _j are the allowable transmission rate and the requested rate of connection j, respectively.
n is the number of connections transmitting data. Further, α _j and w are weighting functions, and sign {} is a function representing the sign of the value in {}.

Α _j may be a positive constant or a value equal to the absolute value of {n · ccr _j / r _j −w · Σ _i ccr _i / r _i }. In particular, when a constant is used as α _j , ERG _j changes instantaneously as α _j increases, but the error increases, and conversely, if α _j is small, it takes time to change ERG _{j though} it is accurate. It can be set arbitrarily, keeping in mind that

W is a decreasing function of the total input bandwidth of the transmission line or route shared by the connections. Specifically, the function w = (B _all + p ₁ ) / (B _use + p ₂ ) × p ₃ of the total bandwidth B _all of the transmission lines or routes shared by the connections and the total input bandwidth B _use Is good. However, p ₂ is a constant for preventing the denominator from becoming zero, p ₁ is a correction constant for p ₂ ,
p ₃ is a constant for setting the swing width. Further, the function w = −p ₄ · B _use + p ₅ of the total input bandwidth B _use of the transmission line or route shared by the connection can be set. p ₄ is a positive constant for setting the shake width, and p ₅ is a constant for correction.

When the requested rate of each connection is not clear, the maximum possible allowable transmission rate of the connection is regarded as the requested rate when the terminal is transmitting at a certain rate or more of the current allowable transmission rate. In other cases, the minimum value of the allowable transmission rate should be considered as the required rate.

[0019]

FIG. 1 is a block diagram showing a first embodiment of the present invention. Here, description will be made focusing on the connections 41 to 43 between the terminals 11 to 13 and the terminals 21 to 23 that allow the transmission paths. That is, the terminal 11
And 21, 12 and 22, 13 and 33 are the transmission lines 5 respectively.
They are connected to each other by the connections 41 to 43 passing through the exchanges 31 to 33 which are connected to each other via 1 and 52, and exchange information at a variable transmission rate. Exchange 3
A switching unit 301 that performs circuit switching in each of 1 to 33.
And control of the exchange unit 301, notification of information about an acceptable transmission rate to the terminals 11 to 13 on the originating side of the connections 41 to 43 to be accommodated, an allowable transmission rate allowed for the connections 41 to 43, and Holds the information collected by the control unit 302, which collects the actual transmission rate, the total bandwidth and the total input bandwidth of the shared transmission line, and the number of connections that share the transmission line Storage unit 303
And an arithmetic unit 304 that calculates an acceptable transmission rate for notifying the terminals 11 to 13 on the originating side for each connection based on the information held in the storage unit 303.

In this structure, the terminals 11 to 13 on the calling side
Generates a control cell at regular intervals of the number of cells and transmits it to the destination terminals 21 to 23. The control cell is provided with a CCR field for notifying an allowable transmission rate of each connection and an ER field for notifying an acceptable transmission rate. When transmitting the control cell, the originating terminals 11 to 13 use the CCR field to indicate the current allowable cell rate ACR _j (j = 1, 2, ..., And) of each connection.
n) is written.

Each control unit 30 of the exchanges 31 to 33
2 is the number of passing connections n, the total bandwidth B _all and the total input bandwidth B _use of the transmission path on the output side, and the current transmission rate rate _j (j = 1, 2,
..., n) is measured, and the information is stored in the storage unit 3 in the exchange.
Keep it at 03. Also, the allowable transmission rate information for each connection written in the CCR field of the control cell passing through the exchange is read, and ccr _j (j = 1, 2,
, N), the information is stored in the storage unit 303 in each exchange.

2 to 4 are diagrams showing the flow of control by the exchange. FIG. 2 shows the calculation of an acceptable transmission rate, FIG. 3 shows the measurement of the transmission rate, and FIG. 4 shows when the control cell arrives. Controls are shown respectively. Here, the exchange 32
Will be described as an example. Here, each connection j (j = 1,
2, ..., N), the maximum value and the minimum value that the allowable transmission rate can take at the time of call connection are determined by negotiation with the communication network. The maximum value is represented by PCR _j (Peak Cell Rate) and the minimum value is represented by MCR _j (Minimum Cell Rate).

The exchange 32 has the number of connections n, the total bandwidth B _all , the total input bandwidth B _use , and the current transmission rate ra.
te _j , allowable transmission rate ccr _j (j = 1, 2, ...,
Each data of n) is held in the storage unit 303.

The exchange 32 has an allowable transmission rate and an actual transmission rate for each connection, that is, ccr ₁ and ra.
te ₁ , ccr ₂ and rate ₂ , ccr ₃ and rate ₃
And the actual transmission rate rate _j is equal to or higher than a certain ratio of the allowable transmission rate, that is, rate _j > ccr _j
If G (G is a constant of 0 or more and 1 or less), the requested cell rate r _j (j = 1, 2, ..., N) of the connection _j is regarded as PCR _j . On the contrary, when the transmission rate is less than the fixed rate, the requested cell rate of the connection is regarded as MCR _j . The value of G, the dispersion V of the ratio of the allowable transmission rate to requested rate for each connection _{({ccr 1, ccr 2,} ..., ccr n}, {r 1, r 2, ..., r n}) = (1 /
n) Σ _j (ccr _j / r _j − (1 / n) Σ _i ccr _i / r _i ) ² is determined as the evaluation function. Then, the arithmetic unit _{304, ERQ j = ccr j -α} j · sign {n · ccr j / r j -w · Σ i ccr / r
_i } to calculate an acceptable transmission rate ER at exchange 32 for connection j (j = 1, 2, ..., N).
G _j is required. However, Σ _i and Σ _j are i,
j = 1 to n total, ccr _j and r _j are the allowable transmission rate and the required rate of connection j, n is the number of connections transmitting data, α _j and w are weighting functions, and s
ign {} is a function that represents the sign of the value in {}.

As α _j , a positive constant value that differs for each connection is set. w is a reduction function of the total input bandwidth of the transmission line shared by the connections, for example, a function of the total bandwidth B _all and the total input bandwidth B _use of the transmission line shared by the connections w = (B _all + p ₁ ) / (B _use + p ₂ ) × p ₃ . However, p ₂ is a constant for preventing the denominator from becoming zero, p ₁ is a correction constant for p ₂ , and p ₃ is a constant for setting the swing width.

As α _j , a value equal to the absolute value of {n · ccr _j / r _j −w · Σ _i ccr _i / r _i } may be used. Also, as w,
It is also possible to set the function w = −p ₄ · B _use + p ₅ of the total input bandwidth B _use of the transmission line shared by the connections. However, p ₄ is a positive constant for setting the shake width, and p ₅ is a constant for correction.

The exchange 32 is further similar to the prior art,
When the newly calculated acceptable transmission rate is smaller than the acceptable transmission rate written in the ER field of the control cell returned by the destination terminal, the ER field is rewritten to the newly calculated value, Otherwise, the control cell is relayed next without rewriting and the calling terminal is notified. However, when the calling terminal of connection j generates a control cell, PCR _j of connection _j is written in the ER field.

FIG. 5 is a diagram showing a second embodiment of the present invention, in which only the subscriber exchange calculates the acceptable transmission rate. An example of the configuration is shown. In this configuration, the transmission line 5
A plurality of exchanges 31 to 31 connected to each other via 1, 52
32 and a plurality of terminals 11-13, 21-2 which are connected to each other by connections 41-43 passing through these exchanges 31-32 and which transmit and receive information at a variable transmission rate.
3, the exchange 31 which directly accommodates the terminals 11 to 13 on the originating side, when the terminals 11 to 13 accommodated therein are the originating terminals, the transmission rate acceptable to the terminals 11 to 13 A control unit 302 for notifying information regarding Further, the exchange 31 is provided with the terminals 11 accommodated therein.
~ 13 is a source terminal, for a plurality of connections that share a route with the connection, the allowable transmission rate and the actual transmission rate allowed for each connection, the bandwidth of the shared route and the total input bandwidth, and A storage unit 303 that collects and holds each piece of information about the number of connections sharing a route, and an arithmetic unit that calculates an acceptable transmission rate for notifying the terminal based on the information held in the storage unit 303 for each connection Thirty
4 is provided.

That is, the exchange 31 rewrites the control cells arriving from the terminals 11 to 13 to the newly-acceptable transmission rates calculated by the exchange 31 and returns the control cells to the original terminals. Thereby, the acceptable transmission rate is notified to the calling terminal.

In the above embodiments, the acceptable transmission rate is notified to the terminal. However, the terminal is notified of the information for instructing the increase / decrease of the allowable transmission rate, and the terminal allows its own acceptance according to a predetermined calculation formula. The transmission rate can be increased or decreased. For example, when the acceptable transmission rate newly calculated by the exchange becomes a value smaller than the current allowable transmission rate used for calculation, write that there is congestion in the control cell returned by the destination terminal. , And notifies it to the destination terminal. The destination terminal may automatically reduce the allowable transmission rate when the congestion is notified.

[0031]

As described above, according to the adaptive transmission rate control communication device of the present invention, the permissible transmission rate and the actual transmission rate allowed for each connection, the total bandwidth and the total input of the transmission line to be shared. Each piece of information about the bandwidth and the number of connections sharing the transmission line is collected and held, and an acceptable transmission rate for notifying the originating terminal is calculated for each connection based on the information. As a result, the acceptable transmission rate for each connection can be changed so as to maximize the usable bandwidth of each connection while satisfying the fairness.

Further, when only the exchange that accommodates the calling terminal notifies the calling rate of the acceptable transmission rate to the calling terminal, the load required for generating and notifying the control information in the switching equipment in the communication network is reduced, and each connection is connected. When there is a change in the transmission rate, the time required to calculate the acceptable transmission rate according to the change is short, the notification to the calling terminal can be sent at high speed, and the transmission that all exchanges can accept Even if the rate is not calculated, it can be calculated only by the subscriber exchange, and the rate can be immediately controlled even when a new connection starts transmission.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a flow of control by an exchange, showing a calculation of an acceptable transmission rate.

FIG. 3 is a diagram showing control regarding measurement of a transmission rate.

FIG. 4 is a diagram showing control when a control cell arrives.

FIG. 5 is a block diagram showing a second embodiment of the present invention.

FIG. 6 is a diagram illustrating conventional rate control.

FIG. 7 is a diagram showing a flow of control in the exchange, showing a control when it is determined that there is congestion.

FIG. 8 is a diagram showing a flow of control of the exchange when a control cell arrives from the calling terminal side.

FIG. 9 is a diagram showing a flow of control of the exchange when the control cell is returned from the destination terminal side.

FIG. 10 is a diagram showing a flow of control of the exchange when it is determined that there is no congestion.

[Explanation of symbols]

11-13, 21-23, 611-613, 621-6
23 Terminals 31 to 33, 631 to 633 Exchanges 41 to 43, 641 to 643 Connections 51, 52, 651, 652 Transmission line 301 Exchange section 302 Control section 303 Storage section 304 Calculation section

Claims (11)

[Claims] 1. A plurality of exchanges connected to each other via a transmission line, and a plurality of terminals connected to each other by a connection passing through one or a plurality of the plurality of exchanges and transmitting / receiving information at a variable transmission rate. In the adaptive transmission rate control communication device, wherein each of the plurality of exchanges has a means for notifying information regarding an acceptable transmission rate to the terminal on the side of the connection that it accommodates, wherein each of the plurality of exchanges is For multiple connections that are accommodated in the exchange and share a transmission line, specify the allowable transmission rate and actual transmission rate allowed for each connection, the total bandwidth and the total input bandwidth of the shared transmission line, and the transmission line. A means for collecting and holding each piece of information on the number of shared connections and the information held by this holding means. Adaptive transmission rate control communication apparatus, wherein said notification to means and means for calculating an acceptable transmission rate to notify the caller terminal for each connection based on. 2. A plurality of exchanges connected to each other via a transmission line, and a plurality of terminals connected to each other by a connection passing through one or a plurality of the plurality of exchanges and transmitting / receiving information at a variable transmission rate. An exchange that directly accommodates a terminal on the originating side of the plurality of exchanges, when the accommodated terminal is the originating terminal,
In an adaptive transmission rate control communication device including means for notifying information regarding an acceptable transmission rate to the terminal, in an exchange that directly accommodates the terminal that is the originating side, the terminal that accommodates the terminal becomes the originating terminal. For multiple connections that share a route with a connection, the allowable transmission rate and the actual transmission rate allowed for each connection, the bandwidth of the shared route and the total input bandwidth, and the number of connections sharing the route A means for collecting and holding each information, and a means for calculating an acceptable transmission rate notified by the notifying means for each connection based on the information held in the holding means Adaptive transmission rate control communication device. 3. The information notified to the terminal by the notifying means is information for instructing an increase / decrease of an allowable transmission rate, and each of the plurality of terminals increases or decreases its own allowable transmission rate according to a predetermined calculation formula. 3. The adaptive transmission rate control communication device according to claim 1, further comprising: 4. The calculating means calculates the variance V ({ccr ₁ , ccr ₂ , ..., Ccr _n }, {r ₁ , r ₂ , ..., R _n) of the ratio of the allowable transmission rate to the request rate of each connection. }) = (1 /
n) Σ _j (ccr _j / r _j − (1 / n) Σ _i ccr _i / r _i ) ² as an evaluation function, ERQ _j = ccr _j −α _j · sign {n · ccr _j / r _j −w・ Σ _i ccr / r
The adaptive transmission rate control communication according to any one of claims 1 to 3, further comprising arithmetic means for obtaining an acceptable transmission rate ERG _j at the exchange for connection j (j = 1, 2, ..., N) by _i }. apparatus. Where Σ _i and Σ _j are the sums of i and j = 1 to n, ccr _j and r _j are the allowable transmission rate and the requested rate of connection j, and n
Is the number of connections transmitting data, α _j and w are weighting functions, and sign {} is a function representing the sign of the value in {}. 5. The adaptive transmission rate control communication device according to claim 4, wherein α _j is a positive constant. 6. The adaptive transmission rate control communication device according to claim 4, wherein α _j is a value equal to an absolute value of {n · ccr _j / r _j −w · Σ _i ccr _i / r _i }. 7. The adaptive transmission rate control communication device according to claim 4, wherein w is a decreasing function of the total input bandwidth of the transmission line or route shared by the connections. 8. w is a function w = (B _all + p ₁ ) / (B _use + p ₂ ) × p ₃ of the total bandwidth B _all of the transmission lines or routes shared by the connections and the total input bandwidth B _use The adaptive transmission rate control communication device according to claim 7. However, p ₂ is a constant for preventing the denominator from becoming zero, p ₁ is a correction constant for p ₂ , and p ₃ is a constant for setting the swing width. 9. The adaptive transmission rate control communication device according to claim 7, wherein w is a function w = −p ₄ · B _use + p ₅ of the total input bandwidth B _use of the transmission line or route shared by the connections. However, p ₄ is a positive constant for setting the shake width, and p ₅ is a constant for correction. 10. The calculating means can take the allowable transmission rate of the connection when the request rate of each connection is not clear and when the terminal is transmitting at a certain rate or more of the current allowable transmission rate. 5. The adaptive transmission rate control communication device according to claim 4, further comprising: a unit that regards the maximum value as a requested rate, and otherwise considers a minimum value that an allowable transmission rate can take as a requested rate. 11. A switching device used as a switching device of the adaptive transmission rate control communication device according to claim 1. Description: