JP3085516B2 - Adaptive transmission rate control communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a packet switching network or an asynchronous transfer mode (ATM).
er Mode) It relates to rate control and traffic control in a network.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional packet network or ATM.
FIG. 3 is a diagram illustrating rate control in a network. here,
Terminals 611 to 613 are originating terminals, and exchanges 631 to 63-6 are provided between terminals 621 to 623, which are destination terminals.
It is assumed that connections 641, 642, and 643 are established via the connection 33. These connections 641, 6
42 and 643 are transmission lines 65 between the exchanges 631 to 633.
1, 652 are commonly used. The rate control is performed as follows. In other words, the terminals 611-
A control cell 613 generates and inserts a control cell at regular cell intervals, reciprocates the control cell between terminals 621 to 623, which are destination terminals, and exchanges 631 to 633 write information to the cell and transmit the information. The terminals 611 to 613, which are terminals, perform rate control with reference to them.

For example, ATM Forum specifications (95-0013R
ABR (Available Bi) by 2, 94-0983, 95-0195, etc.
In the rate control used in the “t Rate” protocol, the originating terminal is controlled fairly and without congestion in accordance with the available bandwidth and the required bandwidth of the route sharing the transmission rate of each connection. A control cell is transmitted at every cell interval, and each exchange through which the control cell passes reads the allowable transmission rate of the terminal from the control cell, and calculates congestion information and an acceptable transmission rate for the exchange itself.
In the control cell, the maximum value (PCR) of the allowable transmission rate for each connection is described as an initial value of an acceptable transmission rate when the calling terminal transmits. Only when the acceptable transmission rate calculated by the exchange is smaller than the acceptable transmission rate written in the returning control cell, each exchange writes the calculated rate in the control cell and sends it to the calling terminal. Notice. The calling terminal sets its own allowable transmission rate (ACR: Allowed Cell Rate) below the notified acceptable transmission rate, and performs transmission at a rate equal to or lower than the ACR.

FIGS. 7 to 9 are diagrams showing the flow of control in the exchange, and FIG. 7 shows control when congestion is determined.
FIG. 8 shows control when a control cell arrives from the calling terminal side,
FIG. 9 shows control when the control cell is looped back from the called terminal. Each exchange observes the queue length in the transmission waiting cell buffer. If the queue exceeds the threshold value, it judges that its own exchange is congested, and otherwise judges that it is not congested. Then, when it is determined that the state is congested, a value obtained by reducing the current allowable transmission rate at a fixed rate is calculated as an acceptable transmission rate in the exchange.

The 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. When the control cell arrives from the calling terminal, the current allowable transmission rate ccr _j written in the control cell is ccr
_j × min (1, R ₀ / rate _j ) is obtained and 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 . Here, 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 Into ERQ _j ,
As if ERQ _j ≧ ER _c, it relays the control cell to the source terminal.

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

FIG. 10 shows a control flow of the exchange when it is determined that there is no congestion. If it is determined that there is no congestion, the exchange increases the acceptable transmission rate in the exchange from 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 one with the smallest _j × ERU and R ₀ is a new ERQ _j, and the one with the largest ERQ _j and MACR _j × ERD is a new ERQ _j . The control when the control cell arrives from the calling terminal side and the control when the control cell is looped back from the destination terminal side are the same.
CR increases.

[0008]

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

SUMMARY OF THE INVENTION The present invention solves such a problem and aims to change the direction in which the available bandwidth of each connection is maximized while satisfying the fairness of an acceptable transmission rate notified between the connections. It is an object of the present invention to provide an adaptive transmission rate control communication device that can perform the control.

[0010]

SUMMARY OF THE INVENTION An adaptive transmission rate control communication device according to the present invention comprises: a plurality of connections accommodated in an exchange and sharing a transmission line; Acceptable transmission that collects and retains information on all bandwidths and all input bandwidths of the shared transmission path and the number of connections sharing the transmission path, and notifies the originating terminal based on the information. The rate is calculated for each connection.

[0011] Thereby, the receivable transmission rate notified between each connection is not rewritten in the same direction as increase or decrease as a whole, but is rewritten individually in a direction to increase fairness and notified. Can be. Also, the transmission rate that can be accepted for each connection can be rewritten and notified in a direction to increase the available bandwidth of each connection within a range where congestion does not occur.

[0012] Only the exchange accommodating the calling terminal can notify the calling terminal of the acceptable transmission rate.
In this case, the exchange directly accommodating the terminal that is the originating terminal has, for a plurality of connections that share the route with the connection that is the originating terminal, the permissible transmission rate allowed for each connection and the actual transmission rate. Transmission rate, the bandwidth of the shared route and the total input bandwidth, and a means for collecting and holding each information of the number of connections sharing the route, based on the information held in the holding means, Preferably, a means for calculating an acceptable transmission rate notified by the notifying means for each connection is provided.

[0013] In this case, the load required to generate and notify the control information in the exchanges in the communication network is reduced, and when the transmission rate of each connection changes, the acceptable transmission rate corresponding to the change is reduced. The time required for the calculation is short, the notification to the calling terminal can be performed at high speed, and the calculation can be performed only by the local exchange without calculating the transmission rate that can be accepted by all exchanges. When the transmission starts, the rate can be controlled immediately.

The information notified by the notifying means to the terminal may be the data of the transmission rate itself, or may be the information instructing to increase or decrease 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 means for calculating is a variance V ({ccr ₁ , ccr ₂ ,..., Ccr _n }, Δr ₁ , r ₂ ,. r _n ｝) = (1 / n) Σ _j (ccr _j / r _j − (1 / n) Σ _i ccr _i / r _i ) ² and ERQ _j = ccr _j −α _j · sign ｛n・ Ccr _j / r _j −w ・ Σ _i ccr _i / r
The _i}, connection j (j = 1,2, ..., n) may include a computing means for determining the transmission rate ER Q _j acceptable in that switch on. Where Σ _i and Σ _j are the sum of i, j = 1 to n, ccr _j and r _j are the allowable transmission rate and request rate of connection j, respectively, and n is the number of connections transmitting data. Also,
α _j and w are weight 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 · { _i ccr _i / r _i }}. Particularly in the case of using a constant as alpha _j is, alpha _j greater the ER Q _j is but error increases instantaneously changed, it takes time to correct a certain but change ER Q _j Smaller alpha _j in the opposite 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 connection. Specifically, the function w = (B _all + p ₁ ) / (B _use + p ₂ ) × p ₃ of the total bandwidth B _all of the transmission path or route shared by the connection and the total input bandwidth B _use Is good. Here, 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 amplitude. Further, a function w = −p ₄ · B _use + p ₅ of the total input bandwidth B _use of the transmission path or the route shared by the connection may be used. p ₄ is a positive constant for setting the amplitude, p ₅ is a constant for correction.

If the request rate of each connection is not clear, if the terminal is transmitting at a certain rate or more of the current allowable transmission rate, the maximum value of the allowable transmission rate of the connection is regarded as the request rate. Otherwise, the minimum possible transmission rate may be considered as the requested rate.

[0019]

FIG. 1 is a block diagram showing a first embodiment of the present invention. Here, the description will focus on the connections 41 to 43 between the terminals 11 to 13 and the terminals 21 to 23 that allow the transmission path. That is, the terminal 11
And 21, 12 and 22, 13 and 33 are transmission lines 5 respectively.
They are connected to each other by connections 41 to 43 via exchanges 31 to 33 which are connected to each other via 1 and 52, and transmit and receive information at a variable transmission rate. Exchange 3
Switching units 301 for performing circuit switching are respectively denoted by 1-3.
Control of the switching unit 301, notification of information on an acceptable transmission rate to the originating terminals 11 to 13 of the connections 41 to 43 to be accommodated, an allowable transmission rate allowed for the connections 41 to 43, and A control unit 302 that collects information on 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, and holds the information collected by the control unit 302. Storage unit 303
And an operation unit 304 that calculates an acceptable transmission rate for each connection, which is to be notified to the calling terminals 11 to 13 based on the information held in the storage unit 303.

In this configuration, the originating terminals 11 to 13
Generates a control cell at intervals of a fixed number of cells, and transmits the control cell to 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 cells, the originating terminals 11 to 13 store the current allowable cell rate ACR _j (j = 1, 2,...) Of each connection in the CCR field.
Write n).

Each control unit 30 of the exchanges 31 to 33
2 is the number n of connections that pass, the total bandwidth B _all and the total input bandwidth B _{use of} the output-side transmission path, and the current transmission rate rate _j (j = 1, 2,
.., N), and the information is stored in the storage unit 3 in the exchange.
03. Also, the permissible 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 the state when a control cell arrives. The control is shown respectively. Here, the exchange 32
Will be described as an example. Here, each connection j (j = 1, j = 1
In 2,..., N), the maximum and minimum allowable transmission rates are determined by negotiation with the communication network at the time of call connection. 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 a connection number n, a total bandwidth B _all , a total input bandwidth B _use , and a current transmission rate ra.
te _j , the allowable transmission rate ccr _j (j = 1, 2,...,
Each data of n) is stored in the storage unit 303.

The exchange 32 determines the allowable transmission rate and the actual transmission rate for each connection, ie, ccr ₁ and ra
By comparing te ₁ , ccr ₂ with rate ₂ , ccr ₃ and rate ₃ , the actual transmission rate rate _j is equal to or more than a certain ratio of the allowable transmission rate, that is, rate _j > ccr _j · G
If (G is a constant from 0 to 1), the requested cell rate r _j (j = 1, 2,..., N) of the connection j is set to PC
_Assume R _j . Conversely, if the allowable transmission rate is less than a certain percentage, the required cell rate of the connection is M
CR _j . The value of G is the variance of the ratio of the permissible transmission rate to the request rate of each connection V ({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 an evaluation function. Then, the arithmetic unit _{304, ERQ j = ccr j -α} j · sign {n · ccr j / r j -w · Σ i
ccr _i / r _i } to calculate connection j (j = 1, 2,
..., acceptable transmission rates ER Q _j in switch 32 for n) is obtained. Where Σ _i and Σ _j are i, the sum of j = 1 to n respectively, ccr _j and r _j are the allowable transmission rate and request rate of connection j, n is the number of connections transmitting data, and α _j , W are weight functions, and sign ｛｝ is a function representing the sign of the value in ｛｝.

Α _j is a positive constant value that differs for each connection. w is a decreasing function of the total input bandwidth of the transmission path shared by the connection, for example, a function of the total bandwidth B _all and the total input bandwidth B _use of the transmission path shared by the connection w = (B _all + p ₁ ) / (B _use + p ₂ ) × p ₃ . However, p ₂ is a constant for preventing the denominator is zero, p ₁ is a constant for setting a correction constant, p ₃ is amplitude for p _2.

Α _j may be a value equal to the absolute value of {n · ccr _j / r _j −w · { _i ccr _i / r _i }}. As w,
A function of the total input bandwidth B _use of the transmission path shared by the connection may be w = −p ₄ · B _use + p ₅ . However, p ₄ is a positive constant for setting the amplitude, p ₅ is a constant for correction.

The switch 32 further comprises, as in 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 called terminal, the ER field is rewritten to the newly calculated value, Otherwise, without rewriting, the control cell is relayed next and the calling terminal is notified. However, when the originating terminal of the connection j generates the control cell, it is assumed that the PCR _j of the connection _j is written in the ER field.

FIG. 5 is a diagram showing a second embodiment of the present invention, only the subscriber exchange to calculate the acceptable transmission rates to show line Cormorant usage scenario. In this configuration, the transmission path 51,
A plurality of exchanges 31 to 32 connected to each other via
And a plurality of terminals 11 to 13 and 21 to 23 which are connected to each other by connections 41 to 43 via these exchanges 31 to 32 and transmit and receive information at a variable transmission rate. The exchange 31 that directly accommodates the terminal 13 includes a control unit 302 that notifies the terminals 11 to 13 of information on an acceptable transmission rate when the terminal 11 to 13 that acts as an originating terminal. Further, the exchange 31 has terminals 11 to 1 accommodated therein.
3 is an allowable transmission rate and an actual transmission rate permitted for each connection for a plurality of connections sharing a route with the connection that is the originating terminal;
A storage unit 303 that collects and holds information on the bandwidth of the shared route and the total input bandwidth, and information on the number of connections sharing the route, and notifies the terminal based on the information held in the storage unit 303 And an operation unit 304 for calculating an acceptable transmission rate for each connection.

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

In the above embodiment, the terminal is notified of the acceptable transmission rate. However, the terminal is notified of information instructing to increase or decrease the allowable transmission rate, and the terminal determines its own allowable transmission rate 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 smaller than the current allowable transmission rate used for the calculation, the fact that there is congestion in the control cell returned by the destination terminal is written. , And notify it to the receiving terminal. The destination terminal may automatically reduce the allowable transmission rate when notified of the congestion.

[0031]

As described above, the adaptive transmission rate control communication device of the present invention provides an allowable transmission rate and an actual transmission rate permitted for each connection, a total bandwidth and a total input of a shared transmission line. Information on the bandwidth and the number of connections sharing the transmission path is collected and held, and based on the information, an acceptable transmission rate to be notified to the terminal on the calling side is calculated for each connection. As a result, the acceptable transmission rate for each connection can be changed in a direction that maximizes the available bandwidth of each connection while satisfying fairness.

When only the exchange accommodating the originating terminal notifies the originating terminal of the acceptable transmission rate, the load required to generate and notify the control information in the exchange within the communication network is reduced, and each connection is reduced. When the transmission rate changes, the time required to calculate the acceptable transmission rate according to the change is short, the notification to the calling terminal can be performed at high speed, and transmission that can be accepted by all exchanges The rate can be calculated only by the local exchange without calculating the rate, and the rate can be controlled immediately 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 the exchange, and showing calculation of an acceptable transmission rate.

FIG. 3 is a diagram showing control related to 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 for explaining conventional rate control.

FIG. 7 is a diagram showing a control flow in the exchange, and showing control when congestion is determined.

FIG. 8 is a diagram showing a control flow 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 a control cell is looped back from the destination terminal side.

FIG. 10 is a diagram showing a control flow 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 Exchangers 41 to 43, 641 to 643 Connections 51, 52, 651, 652 Transmission path 301 Switching unit 302 Control unit 303 Storage unit 304 Operation unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References IEICE Communication Society Conference B-347 (August 15, 1995) IEICE Technical Report SS E95-14 (May 19, 1995) JP) IEICE Technical Report SS E95-105 (October 20, 1995) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/28 H04L 12/56

Claims (7)

(57) [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 more of the plurality of exchanges and transmitting and receiving information at a variable transmission rate. An adaptive transmission rate control communication device comprising: a plurality of exchanges, each of which includes a unit for notifying a terminal on an originating side of a connection to accommodate the information about an acceptable transmission rate. For a plurality of connections accommodated in the exchange and sharing the transmission line, the allowable transmission rate and the actual transmission rate permitted 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 information on the number of connections to be shared, and information held by the holding means. It means the notification to means viewing contains a means for calculating an acceptable transmission rate to notify the caller terminal for each connection, to the calculation based on _{the, ERQ j = ccr j -α j} · sign { n ・ ccr _j / r _j −w ・ Σ _i ccr _i /
r _i に , connection j (j = 1, 2,..., n)
To determine the acceptable transmission rate ERQ _j at that exchange.
An adaptive transmission rate control communication device, characterized by including a calculating means for determining . Here, Σ _i and Σ _j are i, j = 1, respectively.
To n, ccr _j and r _j are the connection j
Allowable transmission rate and request rate, n is the data transmission
Α _j , w are weight functions, sig
n ｛｝ is a function representing the sign of the value in ｛｝. 2. The adaptive transmission rate control communication device according to claim 1, wherein α _j is a positive constant . 3. The adaptive transmission rate control communication device according to claim 1, wherein α _j is a value equal to the absolute value of {n · ccr _j / r _j −w · { _i ccr _i / r _i }} . 4. w is a transmission path shared by connections
The adaptive transmission rate control communication device according to claim 1 , wherein the adaptive transmission rate control communication device is a decreasing function of the total input bandwidth of the route . 5. w is a transmission path shared by the connection.
Or the total bandwidth Ball of the route and the total input bandwidth Buse
Function _{w = (B all + p 1} ) / (B use + p 2) adaptive transmission rate control communication apparatus according to claim 4, wherein a × p _3. Was
However , p ₂ is a constant for preventing the denominator from becoming zero.
Number, p ₁ is set the correction constant, p ₃ is amplitude for p ₂
Is a constant for 6. w is a transmission path shared by connections
There is adaptive transmission rate control communication apparatus according to claim 4, wherein the function _{w = -p 4 · B use +} p 5 of the total input bandwidth B _use of the route. Was
However, p ₄ is a positive constant for setting the amplitude, p ₅ is the complement
It is a constant for positive. 7. The method according to claim 1, wherein the calculating means requests each connection.
If the rate is not clear, the terminal will send the current allowable transmission rate
If you are sending more than a certain percentage of the
Requires the maximum possible transmission rate for the
Requested rate, otherwise allowed transmission rate
Adaptive transmission rate control communication apparatus according to claim 1 including means regarded as request rate a lowest possible.