JP3328562B2 - Transmittable rate determination notification method and ATM communication node - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM (Asynchro
The present invention relates to a transmittable rate determination notification method for determining a transmittable rate to be notified to each terminal in a communication network and an ATM communication node in a communication network using a (nous Transfer Mode) method.

[0002]

2. Description of the Related Art In a communication network using the ATM system, A
An ABR (Available Bit Rate) service defined as one of the service categories of the TM layer has a maximum transmittable rate (maximum rate) PC when a connection is set up.
R (Peak Cell Rate) and minimum value (minimum guaranteed rate) MC
R (Minimum Cell Rate) is determined by negotiation between the user and the network, and the transmittable rate AC from each connection is set so as to minimize cell loss.
R (Allowed Cell Rate) is set to maximum value PCR and minimum value MC
It is characterized by operating while controlling between R.

[0003] ABR service targets data communication services such as the Internet. In this ABR service, the necessary bandwidth is not reserved in advance, but in that case,
Normally, there is a possibility that cell loss occurs at a high load. Then, in a communication network using the ATM system, discarding of one cell leads to retransmission of the entire packet, and the efficiency of the network may be reduced. Therefore, in the ARB service, the transmittable rate ACR from each connection is adjusted by an operation status notification function between a terminal and a network by a resource management cell (hereinafter simply referred to as an RM cell) in order to avoid a decrease in network efficiency. To avoid network congestion. This RM cell is usually mixed with a cell for information transfer,
Data is exchanged between the transmitting terminal and the receiving terminal at a rate of one cell every several tens of cells.

[0004] In order to perform the above control, the ABR service has a control method called an ER (Explicit Cell Rate) mode. The ER mode is a method in which a node at a congestion point writes an allocated bandwidth for each connection calculated in the node in an RM cell from a terminating terminal, notifies the transmitting terminal, and controls a transmittable rate. Conventional ER
The rate control using the mode is roughly classified into the following two control methods.

In a node, a current transmittable rate (hereinafter, referred to as CCR) stored in a predetermined field in an RM cell sent from each connection and notified to the node from each connection is read, and each transmitting terminal is read. A method of calculating and controlling an average value of CCR (hereinafter, referred to as MACR) from a computer.

For each connection, the state of the CCR, whether or not each connection is active, whether or not another node becomes a bottleneck and cannot be controlled by this node, is managed in the node, and the connection is based on these. Available transmission rate E for each
A method of calculating and controlling RQ.

[0007] Of the two conventional methods in the ER mode described above, in the method using the MACR, the MACR and the ERQ are calculated without discriminating each connection, so that the connection with the MCR higher than the ERQ has a higher CCR. If mixed, the MACR converges higher due to the higher CCR, delays in avoiding congestion delays cell discard, and may reduce network efficiency. Conversely, when a low CCR is mixed from a connection with a PCR lower than the ERQ or a connection where another node is a bottleneck, the MACR converges lower and the bandwidth in the network cannot be used up. there is a possibility.

In the method of managing and controlling the state for each connection, since the ERQ is calculated for each connection, the problem in the method using the MACR may be solved. However, in the method of preparing a table and managing the state for each connection, for example, in the method of managing the latest CCR, an RM cell (hereinafter, referred to as an f-RM cell) from a transmitting terminal is read every time a node arrives. A table for each connection is prepared in the node based on the information on the RM cell (hereinafter, b
−RM cell) arrives at the node, a process of reading the table managing the ERQ calculated for each connection and writing the value to the b-RM cell occurs, so that the processing load is the largest. Become.

As a method for solving the above problem, Japanese Patent Application No. 09-119927 (“Transmittable rate determination method and device and ATM node”) has been proposed. According to this method, even if connections with various negotiation parameters are mixed without performing state management for each connection, a high MCR, a low PCR, or other nodes are used so that the MACR does not converge higher or lower. The node which does not increase the rate as a bottleneck, calculates the MACR except for the CCR of the connection which cannot be controlled by the node, avoids congestion, and can use the bandwidth efficiently to maintain high throughput.

[0010]

However, in the above-mentioned method, since the transmittable rate ERQ is returned to the transmitting terminal uniformly without discriminating for each connection, for example, a high P
The transmittable rate of the CR connection is the same as that of the low PCR connection, and the P
It is not possible to deal with the case where allocating a band corresponding to the CR value is considered to be fair allocation. On the other hand, if the state management is performed for each connection, the ERQ can be calculated for each connection, so that it is possible to comply with various ideas of fairness. If connection is supported, a problem of processing load occurs.

On the other hand, in the above-mentioned method using the MACR, the transmittable rate (ERQ) is calculated uniformly.
Is allocated to each connection according to the weight determined assuming the traffic condition, if the actual traffic condition is different from the assumed traffic condition,
There is a possibility that the input rate may be reduced or a congestion state may be continued.
If the ratio of the number of high-class connections (connections with a large weight) is larger than the assumed ratio, MACR converges higher, congestion avoidance is delayed, cell discards increase, and network efficiency decreases. There is fear. Conversely, if the ratio of the number of low-class connections (connections with low weight) is larger than the assumed ratio, there is a possibility that MACR converges lower and the band in the network cannot be used up. is there.

[0012] An object of the present invention is to solve the above-described problem by controlling the current cell transmission rate C notified from each connection to a node without managing the state for each connection.
The CR is normalized by the weight for each connection, the average value MACR is obtained, and a provisional transmission available rate (provisional transmission available rate) ERQ is calculated according to the state of the load applied to the node around the value. Is weighted and distributed to each connection, so that even when connections of various negotiation parameters (PCR, MCR) requested by the user are mixed, the transmission possible rate determination that can fairly allocate the bandwidth between the users and allocate the bandwidth can be performed. It is to propose a notification method and an ATM communication node.

Here, the above-mentioned “weight” is a parameter assigned to a connection (substantially the same as “user”).
It reflects the importance in band allocation. For example, the connection # 1 is contracted for 30,000 yen per month, and the connection # 2 is contracted for 10,000 yen per month, and when both use the ABR service, a difference is made in the bandwidth allocation according to the difference in charge. Will be fairer. The above weights can be used in such cases. In addition, the weight does not have to be determined only in accordance with the fee as described above, but may be appropriately selected from various factors, reflecting the values of what is fair for the network provider. I just need.

[0014]

In order to solve the above-mentioned problems, the invention according to claim 1 is used in a communication network of an ATM system, and is an average of a current transmittable rate CCR notified from a plurality of connections. Using the value MACR, calculate a provisional transmission available rate ERQ that provisionally determines a transmission available rate to be notified to each connection, and determine a transmission available rate to be notified to each connection based on the provisional transmission available rate ERQ In the possible rate decision notification method,
The weight w for each connection is managed in advance by an intra-node management table, and each time the CCR is notified from the connection, the CCR is determined based on the congestion state of the link and the magnitude relationship between the CCR and the ERQ.
While updating the MACR so as to suppress the fluctuation of the MACR due to, the ERQ is determined at a certain time interval based on the MACR, when the node receives an RM cell toward the transmission side of a certain connection, Reading the weight w for the connection from the intra-node management table, finally determining the transmittable rate to be notified to the connection by w × ERQ, and notifying the finally determined transmittable rate to the connection. Features.

According to a second aspect of the present invention, there is provided a transmission system which is used in a communication network of the ATM system and notifies each connection using an average value MACR of a current transmittable rate CCR notified from a plurality of connections. In a transmittable rate determination notification method for calculating a provisional transmission available rate ERQ in which an available rate is provisionally determined and determining a transmission available rate to be notified to each connection based on the provisional transmission available rate ERQ, a weight w for each connection Is stored in advance in the intra-node management table, the number of arrivals Count of the cell to the link is measured within a certain measurement time interval T, and based on this, the input rate Rate to the node is calculated, and the transmission side of a certain connection is calculated. From the current cell transmission rate CCR
When the node receives a resource management cell (hereinafter, referred to as an RM cell) in which is written, the CCR value is read out, the weight w for the connection is read out from the management table in the node, and the input rate at that time is read.
Exceeds the input rate threshold value R1 for detecting congestion, the MACR update decay coefficient α is used to calculate (1−α) ×
MACR + α × min (MACR, CCR / w)
When the CR is updated and the input rate at that time does not exceed the congestion state detection input rate threshold value R1, using the ERQ managed in the node and a predetermined transmittable rate fluctuation absorption ε, The value of CCR / w is compared with the value of ε × ERQ, and if CCR / w> εERQ, MA
CR is not updated, CCR / w ≦ εERQ, and the input rate Rate is the input rate threshold value R2 for non-congestion state detection.
If smaller, (1−α) × MACR + α × max
(MACR, CCR / w) to update the MACR, C
If CR / w ≦ εERQ and the input rate is larger than the non-congestion state detection input rate threshold R2, the MACR is calculated by (1−α) × MACR + α × CCR / w.
Is updated, and the number of cells in the output waiting buffer to the link in the node is set to a predetermined congestion detection threshold thre.
shold, whether or not the link is in a congested state or a non-congested state, and when it is determined that the link is congested, the updated MACR and the input rate
And a pre-stored rate-of-congestion rate decrease attenuation coefficient β,
Rapid change suppression lower limit value ERD and target input rate R0
Is used to calculate min (β × MACR + (1−β) × R0 / Rat
e × MACR, (1-ERD) × MACR)
Q is calculated, when it is determined that the non-congestion state, the updated MACR, the input rate Rate, the non-congestion rate increase attenuation coefficient γ stored in advance, sudden fluctuation suppression upper limit ERU, And using the target input rate R0, mi
n (γ × MACR + (1−γ) × R0 / Rate × MAC
R, (1 + ERU) × MACR), and calculates the ERQ. When the node receives an RM cell toward the transmission side of the connection, the node reads a weight w for the connection from the intra-node management table, and reads the weight w for the connection. A value obtained by multiplying the weight w by the calculated ERQ is written in the RM cell as a transmittable rate and is notified to the transmitting side.

The invention described in claim 3 is the same as the invention described in claim 2.
In the transmittable rate determination notification method according to the above, instead of storing the weight w for each connection in the intra-node management table in advance, a transmission terminal, or a connection between the transmission terminal and the node is installed for each connection The virtual transmission terminal manages the weight w for the connection, writes the weight w for the connection together with the CCR in the RM cell to the node, and the node transmits the RM cell from the transmission side of the connection to the node. At the time of reception, the CCR and weight w are read from the RM cell, the MACR is updated and the ERQ is calculated using the CCR and the weight w.
When the node receives an M cell, the node reads a weight w for the connection from the RM cell, writes a value obtained by multiplying the read weight w by the calculated ERQ into the RM cell as a transmittable rate, and notifies the transmitting side. It is characterized by doing.

According to a fourth aspect of the present invention, there is provided a transmission system which is used in a communication network of the ATM system and notifies each connection using an average value MACR of a current transmittable rate CCR notified from a plurality of connections. In a transmittable rate determination notification method for calculating a provisional transmission available rate ERQ in which an available rate is provisionally determined and determining a transmission available rate to be notified to each connection based on the provisional transmission available rate ERQ, a weight w for each connection Is stored in advance in the intra-node management table, the number of arrivals Count of the cell to the link is measured within a certain measurement time interval T, and based on this, the input rate Rate to the node is calculated, and the transmission side of a certain connection is calculated. From the current cell transmission rate CCR
And when the node receives a resource management cell (hereinafter, referred to as an RM cell) in which a minimum guaranteed rate MCR determined at the time of connection setting is written for the connection, the CCR value and the MCR value are read and the The weight w is read from the intra-node management table, and when the input rate at that time exceeds the congestion state detection input rate threshold value R1,
(1-α) × MAC using MACR update attenuation coefficient α
When MACR is updated by R + α × min (MACR, (CCR−MCR) / w), and the input rate at that time does not exceed the input rate threshold R1 for detecting congestion,
Using the ERQ managed in the node and the predetermined transmission available rate fluctuation absorption ε, (CCR-MCR) /
The value of w is compared with the value of ε × ERQ, and (CCR-MC
R) / w> εERQ, do not update MACR,
If (CCR-MCR) / w ≦ εERQ and the input rate Rate is smaller than the non-congestion state detection input rate threshold value R2, (1−α) × MACR + α × max (MA
CR, (CCR-MCR) / w) to update the MACR, (CCR-MCR) / w ≦ εERQ, and the input rate Rate is the input rate threshold R2 for non-congestion state detection
If larger than (1−α) × MACR + α × (CC
R-MCR) / w to update the MACR, and determine whether the link is in a congested state or not depending on whether or not the number of cells in the buffer waiting for output to the link in the node exceeds a predetermined congestion detection threshold value threshold. It is determined whether the state is a congestion state. If the state is determined to be a congestion state, the updated MA
CR, the input rate Rate, a pre-stored rate-of-congestion rate decrease attenuation coefficient β, a sudden fluctuation suppression lower limit ERD,
And using the target input rate R0, min (β × MA
CR + (1-β) × R0 / Rate × MACR, (1-ER
D) × MACR) is calculated, and if it is determined that the state is the non-congestion state, the updated MACR, the input rate Rate, the previously stored non-congestion rate increase attenuation coefficient γ, Using the fluctuation suppression upper limit value ERU and the target input rate R0, min (γ × MACR + (1-
γ) × R0 / Rate × MACR, (1 + ERU) × MAC
R), an ERQ is calculated, and when the node receives an RM cell heading for the transmission side of the connection, the node reads an MCR from the RM cell, and reads a weight w for the connection from the intra-node management table, The read weight w is multiplied by the calculated ERQ, and a value obtained by adding the MCR value read from the RM cell is written to the RM cell as a transmittable rate and notified to the transmitting side.

The invention described in claim 5 is the same as the claim 4.
In the transmittable rate determination notification method according to the above, instead of storing the weight w for each connection in the intra-node management table in advance, a transmission terminal, or a connection between the transmission terminal and the node is installed for each connection The virtual transmission terminal manages the weight w for the connection, and writes the weight w for the connection together with the CCR and MCR in the RM cell to the node, and the node transmits the RM cell from the transmission side of the connection. When the node receives, the CC from the RM cell
R, MCR, and weight w are read, MACR is updated and ERQ is calculated using the R, MCR, and when the node receives an RM cell toward the transmission side of the certain connection, the node calculates the weight w for the connection. Read from the RM cell, multiply the read weight w by the calculated transmittable rate ERQ, and add a value obtained by adding the MCR value read from the RM cell to the RM cell as a transmittable rate, and notify the transmitting side. It is characterized by doing.

The invention according to claim 6 is the same as the invention according to claim 2.
In the transmission possible rate determination notification method according to any one of to 5, among the nodes, or the transmission terminal, or a virtual transmission terminal installed for each connection between the transmission terminal and the node, Instead of storing the weight w for each connection in advance, the RM
The value of the MCR written in the cell and the MC stored in advance
Using a reference value MCR ^{* of} R and a parameter δ stored in advance to prevent the weight w from becoming 0 when the MCR is 0, max (MCR, δ) / MCR ^* is calculated as the weight of the connection. w and the MAC using the weight w
R and ERQ are calculated, a transmittable rate is determined based on the calculated result, and the transmission rate is notified to the transmitting side.

The invention according to claim 7 is used in an ATM communication network, and transmits to each connection using the average MACR of the current transmittable rate CCR notified from a plurality of connections. MACR storage means storing the MACR in an ATM communication node which calculates a provisional transmission possible rate ERQ in which provisional transmission rates are provisionally determined and determines a transmission possible rate to be notified to each connection based on the provisional transmission possible rate ERQ ERQ storage means storing the ERQ, a weight management table storing weights w for the respective connections in advance,
Input rate calculating means for calculating an input rate of a cell, detecting means for detecting a CCR from a resource management cell (hereinafter referred to as an RM cell) transmitted from a transmitting side of the plurality of connections, and CCR by the detecting means. If detected, the CCR reads the weight w for the transmitted connection from the weight management table,
The MAC based on the value of CR and the read weight w
MACR updating means for updating the MACR stored in the R storage means; and determining whether the link is in a congested state or a non-congested state.
An ERQ updating unit that updates the ERQ stored in the ERQ storage unit based on the MACR stored in the storage unit and a predetermined parameter, and when the node receives an RM cell heading to the transmission side of each connection. And its R
The weight w for the connection to which the M cell is directed is read from the weight management table, and the transmittable rate determined based on the read weight w and the ERQ stored in the updated ERQ storage means is set to the RM. And writing means for writing to the cell and notifying the transmitting side.

The invention described in claim 8 is the same as the invention described in claim 7.
In the ATM communication node described in the above, the MACR updating means may include a congestion state detection input rate threshold value R1 for determining that the link is in a congested state, and a MACR updating means for determining that the link is in a non-congested state. An input rate threshold value R2 for non-congestion state detection, a MACR update attenuation coefficient α for determining how much the detected CCR is reflected on the MACR, and a value of the detected CCR for the MAC.
R, a first storage means for storing a transmittable rate fluctuation absorption parameter ε for determining whether or not to add to the R, and when a CCR is detected by the detection means,
The weight w for the connection to which R was sent is read from the intra-node management table, and the input rate at that time is
Is greater than the congestion state detection input rate threshold value R1, (1)
MACR is updated by (−α) × MACR + α × min (MACR, CCR / w), and when the input rate Rate does not exceed the congestion state detection input rate threshold value R1, the MACR is stored in the ERQ storage means. Using the ERQ and the transmittable rate fluctuation absorption parameter ε, the value of CCR / w is compared with the value of ε × ERQ. If CCR / w> εERQ, the MACR is not updated and CCR / w ≦ εERQ
And when the input rate Rate is smaller than the non-congestion state detection input rate threshold value R2, (1−α) ×
MACR + α × max (MACR, CCR / w)
When the CR is updated and CCR / w ≦ εERQ and the input rate Rate is larger than the non-congestion state detection input rate threshold value R2, (1−α) × MACR + α × CCR /
It is characterized in that MACR is updated by w.

According to a ninth aspect of the present invention, there is provided a transmission system which is used in an ATM communication network and notifies each connection using an average value MACR of a current transmittable rate CCR notified from a plurality of connections. MACR storage means storing the MACR in an ATM communication node which calculates a provisional transmission possible rate ERQ in which provisional transmission rates are provisionally determined and determines a transmission possible rate to be notified to each connection based on the provisional transmission possible rate ERQ ERQ storage means storing the ERQ, a weight management table storing weights w for the respective connections in advance,
An input rate calculating means for calculating an input rate of a cell; and a CCR from a resource management cell (hereinafter referred to as an RM cell) transmitted from a transmitting side of the plurality of connections and a connection to which the RM cell is transmitted. Detecting means for detecting the minimum guaranteed rate MCR determined at the time of connection setting; and when the detecting means detects the CCR and MCR, the weight w for the connection from which the CCR and MCR have been transmitted is read from the weight management table. MACR updating means for updating the MACR stored in the MACR storage means based on the values of the CCR and MCR and the read weight w, and determining whether the link is in a congested state or a non-congested state. And a MACR stored in the MACR storage means in accordance with the determination result. An ERQ updating unit for updating the ERQ stored in the ERQ storage unit based on a predetermined parameter, and an RM cell directed to the transmitting side of each connection when the node receives the RM cell. The weight w for the connection is read from the weight management table, and the transmittable rate determined based on the read weight w, the MCR, and the ERQ stored in the updated ERQ storage means is written to the RM cell. , Writing means for notifying the transmitting side.

According to a tenth aspect of the present invention, in the ATM communication node according to the ninth aspect, the MACR updating means performs a congestion state detection input rate for determining that the link is in a congestion state. A threshold value R1, a non-congestion state detection input rate threshold value R2 for determining that the link is in a non-congestion state, and a MACR update attenuation count for determining how much the detected CCR is reflected in the MACR. α, and the value of the detected CCR
A first storage unit for storing a transmittable rate fluctuation absorption parameter ε for determining whether to add to the CR, and when the detection unit detects the CCR and the MCR, the CCR is sent. The weight w for the connection is read from the intra-node management table. If the input rate at that time exceeds the congestion state detection input rate threshold value R1, the MACR update decay coefficient α is used as (1- α) × MACR + α × min (MACR,
(CCR-MCR) / w), the MACR is updated, and the input rate is equal to the input rate threshold R for detecting congestion.
If it does not exceed 1, the value of (CCR-MCR) / w and ε × ERQ are calculated using the ERQ stored in the ERQ storage means and the transmittable rate fluctuation absorption parameter ε.
And (CCR-MCR) / w> εERQ, the MACR is not updated, and (CCR-MCR) /
If w ≦ εERQ and the input rate Rate is smaller than the non-congestion state detection input rate threshold R2,
(1−α) × MACR + α × max (MACR, (CCR−
MCR) / w) to update the MACR and (CCR-M
(CR) / w ≦ εERQ and when the input rate Rate is larger than the input rate threshold R2 for non-congestion state detection, (1−α) × MACR + α × (CCR−MCR) / w
It is characterized in that the MACR is updated according to.

According to an eleventh aspect of the present invention, in the ATM communication node according to any one of the seventh to tenth aspects, the ERQ updating means determines the target input rate R0 and the link is in a congested state. And a predetermined rate decrease attenuation coefficient β used in the calculation of the ERQ, and a sudden fluctuation suppression lower limit ER which is a parameter for suppressing the ERQ from becoming insufficiently small.
D and if the link is determined to be in a non-congested state ER
A second storage means for storing a predetermined rate increase attenuation coefficient γ used for calculating Q and a sudden fluctuation suppression upper limit value ERU which is a parameter for suppressing ERQ from becoming excessively large; When it is determined that the state is congested, the MACR, the input rate Rate, the rate decrease decay coefficient β during congestion, the rapid fluctuation suppression lower limit ERD, and the target input rate R0 are used to calculate min (β × MACR + (1
−β) × R0 / Rate × MACR, (1-ERD) × MA
CR), the provisional transmittable rate ERQ is updated, and when it is determined that the state is the non-congestion state, the updated MACR
Min (γ × MAC) using the input rate Rate, the rate increase attenuation coefficient γ, the sudden fluctuation suppression upper limit ERU, and the target input rate R0 stored in advance.
R + (1−γ) × R0 / Rate × MACR, (1 + ER
U) × MACR) is used to update the provisional transmission available rate ERQ.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ATM communication node according to the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram showing a configuration of an ATM communication node according to the present embodiment. In FIG.
1 is an arrival cell number measurement unit, 2 is a Rate calculation unit, 3 is Ra
te management unit, 4 is an f-RM cell detection unit, 5 is a MACR calculation unit, 6 is a MACR management unit, 7 is a cell storage unit, 8 is a buffer cell number management unit, 9 is a cell transfer unit, and 10 is an ERQ calculation. , 11 is an ERQ management unit, 12 is a b-RM cell detection unit, 13 is a rate writing unit, and 14 is a weight management table.

Further, as shown in FIG. 2, the MACR calculation section 5 includes a MACR calculation execution section 51, a state detection threshold value storage section 52, and a smoothing parameter storage section 53. Also,
As shown in FIG. 3, the ERQ calculation unit 10 includes an ERQ calculation execution unit 101, a target input rate storage unit 102, and a smoothing parameter storage unit 103.

Hereinafter, each part will be described. The arriving cell measuring unit 1 counts the number of cells transmitted from the transmitting terminal,
Notify the Rate calculation unit 2. The Rate calculation unit 2 divides the number of cells Count notified from the number-of-arrived-cells measurement unit 1 by the measurement time interval T of the number of cells Count, and inputs the number of cells transmitted to the ATM communication node shown in FIG. Rate Ra
Calculate te. The Rate management unit 3 is a Rate calculation unit 2
, And notifies the ERQ calculation unit 10 of the result.

When the f-RM cell detector 4 detects an f-RM cell from cells transmitted from a transmitting terminal (not shown), it reads the CCR written in the f-RM cell,
It requests the MACR calculator 5 to calculate. Further, it requests the weight management table 14 to read the weight w of the connection to which the f-RM cell belongs. The MACR calculator 5 calculates f
When receiving the CCR from the RM cell detector 4, the state detection threshold storage 52, the smoothing parameter storage 53, and E
RQ management unit 11, weight management table 14, and Rate
The MACR is calculated using the information of the management unit 3. In addition,
This calculation method will be described later.

Upon receiving the notification from the f-RM cell detection unit 4, the MACR calculation execution unit 51 checks the Rate management unit 3, ER
Information of Q management unit 11 and state detection threshold value storage unit 5
2. The MACR is calculated using the information stored in the smoothing parameter storage unit 53 and the weight management table 14 (the calculation method will be described later). The state detection threshold value storage unit 52 stores a predetermined congestion state detection input rate threshold value R1 and a non-congestion state detection input rate threshold value R2, and stores R1 according to an instruction from the MACR calculation execution unit 51. , R2 to the MACR calculation execution unit 51.

The input rate threshold R1 for detecting a congestion state is a value used to determine whether or not the link is in a congestion state. When the input rate exceeds this value, the network is in a congestion state. Is determined. Also,
The non-congestion state detection input rate threshold R2 is a value used to determine whether or not the link is in a non-congestion state. If the input rate Rate falls below this value, the network is in a non-congestion state. Is determined.

The smoothing parameter storage unit 53 stores predetermined smoothing parameters α and ε,
According to the instruction of the calculation execution unit 51, α and ε are calculated by MACR
The calculation execution unit 51 is notified. Here, the smoothing parameter α (attenuation coefficient for MACR update) reflects the current transmittable rate CCR notified from each connection to the node to what extent and reflects the average value MA of the CCR of each connection.
This is a value that determines whether to update the CR. Further, the smoothing parameter ε (transmission rate fluctuation absorption) is obtained by updating the CCR value notified from each terminal when updating the MACR.
This value is used to determine whether or not to add to CR. If CCR> εERQ, the CCR value is MACR
Do not add to

The MACR management section 6 manages the result of calculation by the MACR calculation section 5 and notifies the ERQ calculation section 10 of the result. The cell storage unit 7 temporarily stores cells when a cell transmitted from a transmitting terminal (not shown) arrives at the ATM communication node shown in FIG.

The number-of-cells-in-buffer management unit 8 monitors the number of cells stored in the cell storage unit 7 and determines a predetermined threshold value thre.
If shold is exceeded, congestion is determined and Congflag is set to “1”
Otherwise, the congestion state is managed by setting Congflag to “0” as non-congestion. The cell transfer unit 9 transfers the cells temporarily stored in the cell storage unit 7 according to the link capacity.

ERQ calculation section 10 includes target input rate storage section 102, smoothing parameter storage section 103, and MAC
Using the information of the R management unit 6, the Rate management unit 3, and the number-of-cells-in-buffer management unit 8, a provisionally determined transmittable rate (temporary transmittable rate) ERQ is calculated (the calculation method will be described later). The target input rate storage unit 102 stores a predetermined target input rate R0 and stores the ERQ calculation execution unit 1
01, the ERQ calculation execution unit 10
Send to 1. This target input rate R0 is the input rate
This is the target value of Rate, which is the value of A in this embodiment.
The TM communication node sets the input rate Rate to the target input rate R
The transmittable rate of each connection is controlled so that the value becomes zero.

The smoothing parameter storage unit 103 stores predetermined smoothing parameters β, γ, ERU, and ERD.
The γ, ERU, and ERD are notified to the ERQ calculation execution unit 101. Here, regarding the content of each smoothing parameter,
This will be described below.

Β (decay coefficient for rate reduction during congestion): a value that determines to what extent the measured input rate Rate is reflected when calculating the provisional transmittable rate ERQ. It is used when it is determined by the above-mentioned buffer cell number management unit 8 that the link is in a congested state. γ (decay coefficient for rate increase during non-congestion): input rate measured when calculating provisional transmittable rate ERQ
Value that determines how much is reflected. It is used when the link in the non-congestion state is determined by the above-mentioned buffer cell number management unit 8.

ERU (Early Fluctuation Suppression Upper Limit): A value used to prevent the provisional transmission available rate ERQ from becoming excessively large when the link is in a non-congested state. ERD (sudden fluctuation suppression lower limit value): A value used to prevent the provisional transmission available rate ERQ from becoming insufficiently small when the link is in a congested state.

The values of these parameters are appropriately determined by simulation or the like.

Next, the ERQ management unit 11 manages the calculation result in the ERQ calculation unit 10, and notifies the value according to the instruction of the rate writing unit 13. b-RM cell detector 12
Is the b-RM from the cells sent from the called terminal.
When the cell is detected, the rate writing unit 13 is notified of the detection. Further, it requests the weight management table 14 to read the weight w of the connection to which the b-RM cell belongs. The rate writing unit 13 reads the weight w from the weight management table 14 with reference to the value of the ERQ managed by the ERQ management unit 11, calculates the value of w × ERQ,
Compared with the value already written in the ER field of the b-RM cell, if the calculated w × ERQ is smaller,
In the ER field in the RM cell, the above calculated w × ER
A process of writing the value of Q as a transmittable rate for notification is performed. If the calculated value of w × ERQ is larger, this writing is not performed, and the b-RM cell transmitted from the receiving terminal is transferred to the transmitting terminal as it is.

The weight management table 14 stores a predetermined weight for each connection.
In response to instructions from the cell detector 4 and the b-RM cell detector 12, the weight w of the connection to which the RM cell belongs is read.

Next, the MACR calculation execution section 51,
The MACR calculation method and the ERQ calculation method respectively performed by the ERQ calculation unit 10 will be described below.

[MACR Calculation Method] The MACR calculation execution unit 51 calculates MACR by the following equation. if (Rate> R1) MACR ← (1−α) × MACR ⁻¹ + α × min (MAC
R, CCR / w) else if (CCR / w ≦ εERQ) if (Rate ≦ R2) MACR ← (1−α) × MACR ⁻¹ + α × max (MAC
R, CCR / w) else MACR ← (1−α) × MACR ⁻¹ + α × CCR / we
1se MACR ← MACR ^-1

That is, when an f-RM cell is detected in an arrival cell by the f-RM cell detection unit 4, the MACR calculation execution unit 51 makes the MAR calculation based on the following conditions and calculation formulas.
CR is calculated. (i-1) When the value of the input rate Rate is larger than the input rate threshold value R1 for detecting a congestion state: MACR = (1−α)
× MACR ⁻¹ + α × min (MACR ⁻¹ , CCR / w) Here, MACR ⁻¹ in the above equation is the MAC calculated last time.
R, and min (MACR ⁻¹ , CCR / w) is the MAC
This means that the smaller of R- ¹ and CCR / w is adopted (the same applies hereinafter).

(I-2) When the value of the input rate Rate is equal to or less than the input rate threshold value R1 for detecting congestion: The MACR is calculated according to the following conditions.

(I-2-a) When CCR / w is equal to or smaller than εERQ and the value of the input rate Rate is equal to or smaller than the input rate threshold R2 for non-congestion state detection: MACR = (1-α) ×
MACR ⁻¹ + α × max (MACR ⁻¹ , CCR / w) where max (MACR ⁻¹ , CCR / w) is the MACR
^This means that the larger of ^-1 and CCR / w is adopted (the same applies hereinafter).

(I-2-b) When CCR / w is equal to or smaller than εERQ and the value of the input rate Rate is larger than the input rate threshold R2 for non-congestion state detection: MACR = (1-
α) × MACR ⁻¹ + α × CCR / w (i-2-c) When CCR / w is larger than εERQ: MAC
R = MACR ^-1

[ERQ Calculation Method] The ERQ calculation unit 10
Each time a predetermined measurement time interval T elapses, ERQ is calculated by the following equation. At the time of non-congestion (when congflag = “0”) ERQ = min (γ × MACR + (1−γ) × R0 / Rate × MACR, (1+
ERU) × MACR) During congestion (when congflag = “1”) ERQ = min (β × MACR + (1−β) × R0 / Rate × MACR, (1-
(ERD) × MACR)

Next, the operation of the above-described ATM communication node will be described with reference to FIGS. here,
FIG. 4 is a MACR calculation flowchart, FIG. 5 is an ERQ calculation flowchart, and FIG. 6 is a flowchart showing a procedure for writing the calculated ERQ to the b-RM cell. First, each of the steps SA1 to SA1 in the flowchart of FIG.
Next, the MACR calculation flow will be described with reference to FIG.

First, the ATM communication node shown in FIG.
When the RM cell detecting unit 4 detects an f-RM cell in a cell transmitted from the transmitting terminal, the process proceeds to step SA1.
To the CCR written in the detected f-RM cell.
Is read out and notified to the MACR calculation execution unit 51. Then, the process proceeds to Step SA2, where the MACR calculation execution unit 51
Reads from the weight management table 14 the weight of the connection to which the f-RM cell belongs.

Next, the flow advances to step SA3, where the MACR calculation execution unit 51 sends the current input rate from the Rate management unit 3.
Rate and the congestion state detection input rate threshold R1 are read from the state detection threshold storage unit 52, respectively.
Then, in step SA4, the read input rate Rate
Is compared with the congestion state detection input rate threshold value R1. If the value of the input rate Rate is larger than the congestion state detection input rate threshold value R1, step SA5 is performed.
If the value of the input rate Rate is equal to or less than the input rate threshold value R1 for detecting congestion, the process proceeds to step SA7. Here, it is assumed that the value of the input rate Rate is larger than the input rate threshold value R1 for detecting congestion, that is, the network is in a congestion state, and the process proceeds to step SA5.

At step SA 5, the MACR calculation execution section 51 reads the smoothing parameter α from the smoothing parameter storage section 53 and reads the MACR from the MACR management section 6. Next, proceeding to step SA6, the MACR calculation execution unit 51 updates MACR by the following equation. MACR = (1−α) × MACR ⁻¹ + α × min (MAC
R ^-1 , CCR / w)

As described above, when an f-RM cell is detected from the cells transmitted from the transmitting terminal,
If it is determined that the network is in a congested state when a CCR is notified from a certain connection, the CCR
Value divided by the weight w of the connection or current A
After the smaller one of the MACR values managed by the TM communication node is smoothed by the smoothing parameter α, the MA currently managed by the ATM communication node is
It is added to the value of CR.

On the other hand, if the value of the input rate Rate is equal to or less than the input rate threshold value R1 for detecting congestion in step SA4, the process proceeds to step SA7, where the MACR calculation executing section 51 sends the current Is read out. Then, the process proceeds to Step SA8, and Step S8
A value (CCR / w) obtained by dividing the CCR read at A1 by the weight w read at step SA2 is compared with a value (εERQ) obtained by multiplying the ERQ read at step SA7 by the smoothing parameter ε.

If the value of CCR / w is the value of εERQ, the flow proceeds to step SA9. If the value of CCR is larger than the value of εERQ, the flow proceeds to step SA15. Here, it is assumed that the value of CCR / w is equal to or smaller than the value of εERQ, and the process proceeds to step SA9. Step SA
At 9, the MACR calculation execution unit 51 reads the value of the input rate Rate from the Rate management unit 3 and the input rate threshold value R2 for non-congestion state detection from the state detection threshold value storage unit 52, and proceeds to step SA10. move on.

At step SA10, the value of the input rate Rate read at step SA9 is compared with the input rate threshold R2 for non-congestion state detection. If the value of the input rate Rate is equal to or less than the non-congestion state detection input rate threshold value R2, that is, if it is determined that the network is in the non-congestion state, the process proceeds to step SA11, and the non-congestion state detection When it is larger than the input rate threshold value R2, the process proceeds to Step SA13. here,
It is assumed that the value of the input rate Rate is equal to or less than the non-congestion state detection input rate threshold value R2, and the process proceeds to step SA11.

In step SA 11, the MACR calculation execution unit 51 stores the smoothing parameter α from the smoothing parameter storage unit 53 and the MACR
Is read. Next, proceeding to step SA12, the MACR calculation execution unit 51 updates MACR by the following equation. MACR = (1−α) × MACR ⁻¹ + α × max (MAC
R ^-1 , CCR / w)

That is, the network is not in the congestion state when the CCR is notified from a certain connection, and the value obtained by dividing the CCR value by the weight w of the connection is equal to or less than the value obtained by multiplying the smoothing parameter ε by ERQ. And when it is determined that the network is in a non-congested state, the value obtained by dividing the CCR value by the weight w of the connection or the MACR currently managed by the ATM communication node.
Is smoothed by the smoothing parameter α, and then added to the MACR value currently managed by the ATM communication node.

On the other hand, in step SA10, the value of the input rate Rate is set to the non-congestion state detection input rate threshold value R.
If it is determined that the value is larger than 2 (if it is determined that the state is not the non-congestion state), the process proceeds to step SA13, where the MAC
The R calculation execution unit 51 reads the smoothing parameter α from the smoothing parameter storage unit 53 and reads the MACR from the MACR management unit 6, and then proceeds to step SA14 to update the MACR according to the following equation. MACR = (1−α) × MACR ⁻¹ + α × CCR / w

As described above, from a certain connection, the CCR
When the network is not in the congestion state when the notification of is received, the value obtained by dividing the CCR value by the weight w of the connection is
When it is determined that the value is equal to or less than the value obtained by multiplying the smoothing parameter ε by the ERQ, and the network is not in the non-congestion state, a value obtained by dividing the CCR value by the weight w of the connection is determined by the smoothing parameter α. After smoothing,
It is added to the value of MACR currently managed by the ATM communication node.

Each MACR calculated according to the above procedure
Is managed by the MACR management unit 11, and the MACR calculation execution unit 51 next sends the fR
The apparatus enters a standby state until an M cell is detected. If it is determined in step SA8 that the value of CCR / w is larger than the value of εERQ, the MACR calculation execution unit 51
Proceeds to step SA15, maintains the current MACR value without changing the MACR (MACR = MAC
R ^-1 ).

Next, the ERQ calculation flow will be described along steps SB1 to SB7 of the flowchart of FIG. First, when the measurement time interval T has elapsed, the process proceeds to step SB1, where the ERQ calculation execution unit 101 reads the value of Congflag from the number-of-cells-in-buffer management unit 8, and determines whether or not the state is congested. And the value of Congflag is “1”
If so, it is determined that the state is congested, and the process proceeds to step SB2. Here, it is assumed that the state is the congestion state and the process proceeds to step SB2.

At step SB 2, ERQ calculation execution section 101 reads out target input rate R 0 from target input rate storage section 102 and smoothing parameter β and ERD from smoothing parameter storage section 103. Next, proceeding to step SB3, the ERQ calculation execution unit 101
The value of the input rate Rate is read from the te management unit 3, and in step SB4, the ERQ is updated by the following equation. ERQ = min (β × MACR + (1-β) × R0 / Rate × MACR, (1-ER
D) × MACR) Then, the ERQ calculation execution unit 101 enters a standby state until the measurement time interval T elapses.

On the other hand, if it is determined in step SB1 that the vehicle is in the non-congested state (congflag = "1"), the flow advances to step SB5. In step SB5, the ERQ calculation execution unit 101 stores the target input rate R0 from the target input rate storage unit 102 and the smoothing parameter storage unit 10
3 and the smoothing parameters γ and ERU are read out. Then, the process proceeds to Step SB6, where the ERQ calculation execution unit 101
Reads the value of the input rate Rate from the Rate management unit 3. Next, the process proceeds to step SB7, where the ERQ calculation execution unit 1
01 updates ERQ by the following equation. ERQ = min (γ × MACR + (1-γ) × R0 / Rate × MACR, (1 + E
RU) × MACR) Then, the ERQ calculation execution unit 101 enters a standby state until the measurement time interval T elapses.

As described above, by calculating the ERQ according to the flowchart of FIG. 5, the transmittable rate can be appropriately adjusted, and the rapid fluctuation can be suppressed. The ERQ calculated according to the above procedure is ERQ
After being managed by the RQ management unit 11 and appropriately processed when the b-RM cell is transmitted from the called terminal, the b-RM cell is written in the ER field as a transmittable rate and transferred to the transmitting terminal. To state).

Next, an ERQ write flow will be described along steps SC1 to SC3 of the flowchart of FIG. First, when the b-RM cell detection unit 12 detects a b-RM cell from cells transmitted from the terminating terminal, in step SC1, the rate writing unit 13 determines whether the detected b-RM cell belongs to the cell. The weight w of the connection is read from the weight management table 14. Then, the process proceeds to step SC2, where the rate writing unit 13 sets the ERQ management unit 11
From the ERQ value.

Next, proceeding to step SC3, the rate writing section 13 uses the read value of w and the value of ERQ to
w × ERQ is calculated, and the calculated value of w × ERQ and b−
W × ER already written in the ER field of the RM cell
The value of Q is compared with the value of Q, and if the calculated value of w × ERQ is smaller, the calculated value of w × ERQ is written in the ER field as a transmittable rate for notification and transferred to the transmitting terminal. If the calculated value of w × ERQ is larger, the above-mentioned writing is not performed, and the b-RM cell transmitted from the receiving terminal is transferred to the transmitting terminal as it is.

[Second Embodiment] An ATM communication node according to a second embodiment is an ATM communication node as described in the first embodiment.
Instead of having a weight management table in the communication node, the weight w of the connection is written in the RM cell in the transmitting terminal or in the virtual transmitting terminal installed between the transmitting terminal and the ATM communication node of the present embodiment. Therefore, in the present embodiment, in the ATM communication node of the [first embodiment], instead of the process of reading the weight w from the weight management table 14, the process of reading the weight w from the RM cell when receiving the RM cell is performed. become. Other processes are the same as those in the first embodiment.

[Third Embodiment] Next, an ATM communication node according to a third embodiment will be described. The block configuration of the ATM communication node in the present embodiment is the same as that of the ATM communication node shown in FIGS.
The processing contents in some blocks are different. Hereinafter, blocks that perform processing different from the blocks of the ATM communication node according to the first embodiment, and the contents of the processing will be described with reference to FIGS. 1 and 2.

F-RM cell detector 4: In the first embodiment, a CCR is transmitted from the f-RM cell sent from the transmitting terminal.
Read out only the weight, request the MACR calculation unit 5 to calculate, and request the weight management table 14 to read the weight w of the connection to which the f-RM cell belongs.
In the present embodiment, when an f-RM cell is detected from the cells transmitted from the transmission terminal, the CCR and MCR written in the f-RM cell are read, and a calculation request is sent to the MACR calculation unit 5. It should be noted that the f
-The request for reading the weight w of the connection to which the RM cell belongs is the same as in the first embodiment.

MACR calculation execution unit 51: In the first embodiment, the CCR supplied from f-RM cell detection unit 4,
An input rate Rate stored in the Rate management unit 3, a congestion state detection input rate threshold R 1 and a non-congestion state detection input rate threshold R 2 stored in the state detection threshold storage unit 52, Various determinations are made using the smoothing parameter α stored in the smoothing parameter storage unit 53 and the weight w stored in the weight management table 14, and the MACR is calculated using a calculation formula according to the determination result. I was seeking. On the other hand, the MAC in the third embodiment
The R calculation execution unit 51 performs various judgments and calculates the MACR using the MCR supplied from the f-RM cell detection unit 4 in addition to the various parameters described above. The method of calculating the MACR in the third embodiment will be described later in detail.

B-RM cell detector 12: In the first embodiment, b-RM cells are detected from cells transmitted from the terminating terminal.
When the M cell is detected, the rate writing unit 13 is notified of the fact. However, in the third embodiment, when the b-RM cell is detected from the cells transmitted from the called terminal, the b-RM cell is detected.
The MCR is read from inside the cell and notified to the rate writing unit 13. Note that the detected b-R is stored in the weight management table 14.
It is the same as in the first embodiment in that a request is made to read the weight w of the connection to which the M cell belongs.

Rate writing unit 13: In the first embodiment,
The weight w is read from the weight management table 14 with reference to the ERQ value managed by the ERQ management unit 11, and w
XERQ is calculated, and the value is compared with the value already written in the ER field of the b-RM cell. If the calculated w × ERQ is smaller, the ER field in the b-RM cell is calculated. Was written as a transmittable rate for notifying the calculated value of w × ERQ. In the first embodiment, when the calculated value of w × ERQ is larger, this writing is not performed, and the b-RM cell transmitted from the receiving terminal is directly transferred to the transmitting terminal.

On the other hand, in the third embodiment, b-RM
The MRQ is received from the cell detection unit 12 and the ERQ management unit 1 is received.
The weight w is read out from the weight management table 14 with reference to the ERQ value managed from 1 and MCR + w × ERQ
Is calculated, and the calculated value is compared with the value already written in the ER field of the b-RM cell.
If CR + w × ERQ is smaller, ER of b-RM cell
A process of writing the calculated value of MCR + w × ERQ in the field as a transmittable rate for notification is performed. If the calculated value of MCR + w × ERQ is larger, this writing is not performed and the b-RM cell sent from the called terminal is transferred to the sending terminal as it is.

Next, a method of calculating the MACR in the MACR calculation executing section 51 according to the third embodiment will be described.

[MACR Calculation Method] MA of Third Embodiment
The CR calculation execution unit 51 calculates MACR by the following equation. if (Rate> R1) MACR ← (1-α) × MACR ⁻¹ + α × min (MACR, (CC
R-MCR) / w) else if ((CCR-MCR) / w ≦ εERQ) if (Rate ≦ R2) MACR ← (1-α) × MACR ⁻¹ + α × max (MACR, (CC
R-MCR) / w) else MACR ← (1-α) × MACR ⁻¹ + α × (CCR-MCR) /
weld MACR ← MACR ^-1

That is, when the f-RM cell detecting section 4 detects an f-RM cell in the arrival cell, the MACR calculation executing section 51 makes the MAR calculation based on the following conditions and formulas.
CR is calculated. (i-1) When the value of the input rate Rate is larger than the input rate threshold value R1 for detecting congestion: MACR = (1-α) × M
ACR ^-1 + α × min (MACR, (CCR-MCR) / w)

(I-2) When the value of the input rate Rate is equal to or less than the input rate threshold value R1 for detecting congestion: The MACR is calculated according to the following conditions.

(I-2-a) When (CCR-MCR) / w is equal to or less than εERQ and the value of the input rate Rate is equal to or less than the input rate threshold R2 for non-congestion state detection: MACR =
(1-α) × MACR ⁻¹ + α × max (MACR, (CCR-MCR) /
w) (i-2-b) (CCR-MCR) / w is not more than εERQ, and
When the value of the input rate Rate is larger than the non-congestion state detection input rate threshold value R2: MACR = (1-
α) × MACR ⁻¹ + α × (CCR-MCR) / w (i-2-c) When (CCR-MCR) / w is larger than εERQ: M
ACR = MACR ^-1

Next, the operation of the ATM communication node according to the third embodiment will be described with reference to FIG. 7 and FIG. Here, FIG. 7 is a MACR calculation flowchart, and FIG.
9 is a flowchart showing a procedure for writing a transmittable rate notified based on a calculated ERQ to a b-RM cell. Note that the ATM communication node in the third embodiment also calculates ERQ as in the first embodiment.
The RQ calculation flow is the same as the flowchart of FIG. 5 described in the first embodiment, and a description thereof will be omitted.

First, the MACR calculation flow will be described along steps SA1 to SA14 in the flowchart of FIG. In this figure, steps that perform the same processing as in the flowchart shown in FIG. 4 are denoted by the same reference numerals, and steps that perform different processing are denoted by dashes (').

First, the ATM communication node shown in FIG.
When the RM cell detecting unit 4 detects an f-RM cell in a cell transmitted from the transmitting terminal, the process proceeds to step SA
Proceed to 1 ′, and C written in the detected f-RM cell
The CR and MCR are read out, and the MACR calculation execution unit 51
Notify. Then, the process proceeds to Step SA2, where the MACR
The calculation execution unit 51 reads out the weight w of the connection to which the f-RM cell belongs from the weight management table 14.

Next, the flow advances to step SA3, where the MACR calculation execution unit 51 sends the current input rate from the Rate management unit 3
Rate and the congestion state detection input rate threshold R1 are read from the state detection threshold storage unit 52, respectively.
Then, in step SA4, the read input rate Rate
Is compared with the congestion state detection input rate threshold value R1. If the value of the input rate Rate is larger than the congestion state detection input rate threshold value R1, step SA5 is performed.
If the value of the input rate Rate is equal to or less than the input rate threshold value R1 for detecting congestion, the process proceeds to step SA7. Here, it is assumed that the value of the input rate Rate is larger than the input rate threshold value R1 for detecting congestion, that is, the network is in a congestion state, and the process proceeds to step SA5.

At step SA 5, the MACR calculation execution section 51 reads out the smoothing parameter α from the smoothing parameter storage section 53 and reads out the MACR from the MACR management section 6. Next, proceeding to step SA6, the MACR calculation execution unit 51 updates MACR by the following equation. MACR = (1-α) × MACR ⁻¹ + α × min (MACR, (CC
R-MCR) / w)

Thus, when an f-RM cell is detected from the cells transmitted from the transmitting terminal,
If it is determined that the network is in a congested state when a CCR is notified from a certain connection, the CCR
The value obtained by dividing the value obtained by subtracting the MCR from the value by the weight w of the connection or the value of the MACR currently managed by the ATM communication node, whichever is smaller, is smoothed by the smoothing parameter α. After that, it is added to the value of the MACR currently managed by the ATM communication node.

On the other hand, if the value of the input rate Rate is equal to or less than the input rate threshold value R1 for detecting congestion in step SA4, the process proceeds to step SA7, where the MACR calculation executing section 51 Is read out. Then, the process proceeds to Step SA8 ′, and the value obtained by subtracting the MCR from the CCR read in Step SA1 is
The value divided by the weight w read in step SA2 ((CCR-M
CR) / w) is compared with a value (εERQ) obtained by multiplying the ERQ read in step SA7 by the smoothing parameter ε.

If the value of (CCR-MCR) / w is the value of εERQ, the process proceeds to Step SA9, where the value of CCR is εERQ.
If it is larger than the value, the process proceeds to step SA15.
Here, it is assumed that the value of (CCR-MCR) / w is equal to or smaller than the value of εERQ, and the process proceeds to step SA9. In step SA9, the MACR calculation execution unit 51 sets Ra
The value of the input rate Rate is read from the te management unit 3 and the input rate threshold value R2 for non-congestion state detection is read from the state detection threshold value storage unit 52, and the flow advances to step SA10.

In step SA10, the value of the input rate Rate read out in step SA9 is compared with the value of the input rate threshold R2 for non-congestion state detection. If the value of the input rate Rate is equal to or less than the non-congestion state detection input rate threshold value R2, that is, if it is determined that the network is in the non-congestion state, the process proceeds to step SA11, and the non-congestion state detection When it is larger than the input rate threshold value R2, the process proceeds to Step SA13. here,
It is assumed that the value of the input rate Rate is equal to or less than the non-congestion state detection input rate threshold value R2, and the process proceeds to step SA11.

At step SA 11, the MACR calculation execution section 51 stores the smoothing parameter α from the smoothing parameter storage section 53 and the MACR
Is read. Next, the process proceeds to step SA12 ′, where the MACR
The calculation execution unit 51 updates the MACR according to the following equation. MACR = (1-α) × MACR ⁻¹ + α × max (MACR, (CC
R-MCR) / w)

That is, when the CCR is notified from a certain connection, the network is not in the congestion state, and the value of (CCR-MCR) / w is set to the smoothing parameter ε as ER.
If the value is equal to or less than the value multiplied by Q and the network is determined to be in a non-congested state,
Divided by the weight w of the connection,
Or MACR currently managed by the ATM communication node
Is smoothed by the smoothing parameter α, and then added to the MACR value currently managed by the ATM communication node.

On the other hand, in step SA10, the value of the input rate Rate is set to the input rate threshold R for non-congestion state detection.
If it is determined that the value is larger than 2 (if it is determined that the state is not the non-congestion state), the process proceeds to step SA13, where the MAC
After reading the smoothing parameter α from the smoothing parameter storage unit 53 and reading the MACR from the MACR management unit 6, the R calculation execution unit 51 proceeds to step SA14 ′ and updates the MACR according to the following equation. MACR = (1−α) × MACR ⁻¹ + α × (CCR-MCR) /
w

As described above, from a certain connection, the CCR
Is notified that the network is not in a congestion state and the value of (CCR-MCR) / w is
If it is determined that the value is equal to or less than the value obtained by multiplying by Q and the network is not in the non-congestion state, the value of (CCR-MCR) / w is smoothed by the smoothing parameter α, and then the current ATM communication is performed. It is added to the value of MACR managed by the node.

Each MACR calculated according to the above procedure
Is managed by the MACR management unit 11, and the MACR calculation execution unit 51 next sends the fR
The apparatus enters a standby state until an M cell is detected. If it is determined in step SA8 that the value of CCR / w is larger than the value of εERQ, the MACR calculation execution unit 51
Proceeds to step SA15, maintains the current MACR value without changing the MACR (MACR = MAC
R ^-1 ).

Next, an ERQ write flow will be described along steps SD1 to SD4 in the flowchart of FIG. First, when the b-RM cell sent from the called terminal arrives at the ATM communication node of the present embodiment, the process proceeds to step SD1, where the b-RM cell detecting unit 12
-Read the MCR from the RM cells. Then, the process proceeds to step SD2, where the rate writing unit 13 determines that the arriving b-R
The weight w of the connection to which the M cell belongs is read from the weight management table 14. Then, the process proceeds to step SD3, where the rate writing unit 13 sends the ERQ
Read the value of.

Next, proceeding to step SD4, the rate writing section 13 adds a value obtained by multiplying the value of w and the value of ERQ to the value of MCR read by the b-RM cell detection section 12 ( MCR + w × ERQ) is compared with the value already written in the arrived b-RM cell, and the calculated MCR +
If the value of w × ERQ is smaller, the calculated MCR
The value of + w × ERQ is written in the ER field as the transmission available rate to be notified, and is transferred to the transmitting terminal.
If the calculated value of MCR + w × ERQ is larger, the above-mentioned writing is not performed, and the b-RM cell transmitted from the receiving terminal is transferred to the transmitting terminal as it is.

[Fourth Embodiment] The ATM communication node of the fourth embodiment is different from the third embodiment in that the ATM communication node has the weight management table 14 in the ATM communication node.
In the transmitting terminal or the virtual transmitting terminal installed between the transmitting terminal and the ATM communication node of the present embodiment, the weight w of the connection is written in the RM cell. Therefore, in the embodiment, the ATM of [Third Embodiment]
In the communication node, instead of the process of reading the weight w from the weight management table 14, the process of reading the weight w from the RM cell when receiving the RM cell is performed. Other processes are the same as those in [Third Embodiment].

[Fifth Embodiment] Instead of setting the weight w for each connection in advance in the ATM communication node according to the fifth embodiment as in [First Embodiment] to [Fourth Embodiment],
When the ATM communication node receives an RM cell, the RM cell
Read the MCR from inside the cell, max (MCR, δ) / M
Let CR ^{* be} the weight w of the connection. Where M
CR ^* is a reference value of the MCR stored in the node in advance, and δ is a preset parameter (provided that δ> 0) in order to prevent the weight from becoming 0 when MCR = 0.
It is. Therefore, a weight management table is not required in the ATM communication node, and a process of writing the weight in the RM cell is not required. Other processes are the same as those in [First Embodiment] to [Fourth Embodiment].

Next, the effect of the transmittable rate determination method in each ATM communication node described in the first and third embodiments will be described by simulation. In addition, as a comparison object, MA as in the conventional method was used.
The calculation of CR is simply MACR ← (1−α) × MACR + α
× CCR (α = 1/16), and a simple method of distributing the calculated ERQ to each connection by weight (hereinafter, referred to as a weight distribution method) is also simulated. The specific algorithm is as follows.

[Weight distribution method] MACR update method: MACR ← (1−α) × MACR +
α × CCR ERQ calculation method: 0.75 × MACR <ER <1.25
× Increase or decrease by an amount corresponding to the ratio between the input rate Rate and the target input rate (95% of the link capacity) within the range of MACR. At the time of congestion, ERQ = 0.75 × MACR. ERQ writing: When the b-RM cell arrives, the weight w is read out, written as w × ERQ, and then written to the RM cell.

FIG. 9 shows a simulation model used for the evaluation. In FIG. 9, the source groups (SG) of the transmitting terminal and the receiving terminal are SG1 to SG5, respectively.
It has five connections (therefore, the total number of connections of the transmitting terminal and the receiving terminal is 25
Becomes). In addition, each of the five source groups is connected to two nodes (node 1 and node 2 in FIG.
Share [Mbps] link. Source group i
Various traffic conditions are simulated by changing the combination of PCRi and MCRi (i = 1 to 5). Furthermore, each connection has an initial rate = 6 [Mbps],
At time 0 [sec], the active state is activated at the same time, and a cell to be transmitted always exists on the transmitting terminal side.

The values of various parameters used in this simulation are as follows. -Target input rate R0 = 0.95 x 150 [Mbps];-Congestion state detection input rate threshold R1 = 0.98 x
150 [Mbps]; input rate threshold R2 = 0.98 for non-congestion state detection
× 150 [Mbps]; transmission possible rate fluctuation absorption ε (first embodiment) = 1; transmission possible rate fluctuation absorption ε (third embodiment) = 100000
00: Attenuation coefficient for MACR update α = 1/16; Attenuation coefficient for rate decrease during congestion β = 0.25; Attenuation coefficient for rate increase during non-congestion γ = 0.75; Rapid change suppression upper limit ERU = 1; ・ Sudden fluctuation suppression lower limit ERD = 1/16; ・ Measurement period T = 100 × (53 × 8/150) [μse
c]; ・ Congestion detection threshold value (threshold) = 256 [cell]
(The buffer size is 4096 [cell])

The simulation conditions were PCR / MCR
= 150 [Mbps] / 3 [Mbps] Class 1, PCR / MCR =
50 [Mbps] / 1 [Mbps]) class 2 and two classes are mixed. That is, class 1 has three times the priority of class 2.

Further, in evaluating the ATM communication node of this embodiment, the following two simulations were performed.

[Simulation 1] When the number of active connections of class 2 is larger than the assumed number of active connections: the combination of the number of active connections (total number is 25) is 15 for class 1 and 10 for class 2; Simulate two cases where 1 is 5 and class 2 is 20. In the case of, PCR1 / MCR1 = PCR2 / MCR2 = PCR3 / MCR3 = 150 [Mbps] /
3 [Mbps] PCR4 / MCR4 = PCR5 / MCR5 = 50 [Mbps] / 1 [Mbps] In this case, PCR1 / MCR1 = 150 [Mbps] / 3 [Mbps] PCR2 / MCR2 = PCR3 / MCR3 = PCR4 / MCR4 = PCR5 / MCR5 = 50
[Mbps] / 1 [Mbps]

Further, the weights of the weight distribution method are set so that the ratio of the number of active connections is 15 for class 1 and 10 for class 2 so as to satisfy the following. ｛(W_high × ERQ) × 15 + (w_low × ERQ) × 1
0｝ / 25 = ERQ (where w_high: w_low = 3: 1) At this time, the weight of class 1 is w_high = 75/55, and the weight of class 2 is w_low = 25/55.

[Simulation 2] When the number of active connections of class 1 is larger than the assumed number of active connections: the combination of the number of active connections is 10 for class 1 and 15 for class 2;
Simulate two cases where class 1 is 20 and class 2 is 5.

The weight of the weight distribution method indicates the ratio of the number of active connections, that is, 10 for class 1 and 1 for class 2.
Assuming that 5 is set so as to satisfy the following. ｛(W_high × ERQ) × 10 + (w_low × ERQ) × 1
5｝ / 25 = ERQ (however, w_high: w_low = 3:
1) At this time, the weight of class 1 is w_high = 75/45, and the weight of class 2 is w_low = 25/45.

Note that the weights in [First Embodiment] and [Third Embodiment] can be set regardless of the combination of the number of active connections.
[Simulation 2], w_high = 1, w_low = 1
/ 3. Below, based on these conditions,
The results of the simulation are described.

[Simulation 1] FIG. 10 shows the transmission rate of each system when the combination of the number of active connections is changed in Simulation 1. In this figure, (a) shows that the number of active connections of class 1 is 15, and the number of active connections of class 2 is 1
The transmission rate when the number of active connections of class 1 is 5 and the number of active connections of class 2 are 20 are shown in FIG. The figure also shows the target transmission rate. The target transmission rate is obtained as follows.

Target transmission rate of class 1 = 3 × R0 / {(number of connections of class 1) × 3 + (number of connections of class 2) × 1} target transmission rate of class 2 = 1 × R0 / ｛(class 1 connection number) x 3 + (class 2 connection number) x 1

FIG. 11 shows the transient behavior of the input rate when the number of active connections is class 1 → 5 and class 2 → 20, and FIG. 12 shows the class 1 → 5,
The transition behavior of the transmission rate of class 1 when class 2 → 20 is shown. As can be seen from these figures, in the ATM communication nodes of the [first embodiment] and [third embodiment], the transmission rate can be converged to the target transmission rate under any conditions, but the [weight distribution method] ( In the conventional method), the combination of the number of active connections is different from that assumed, and when the number of connections of class 2 is large,
The transmission rate becomes lower than the target transmission rate (see FIG. 10). As a result, the link has not been effectively used up (see FIG. 11).

[Simulation 2] FIG. 13 shows the transmission rate and the target transmission rate of each system in simulation 2 when the combination of the number of active connections is changed. In this figure, (a) shows the transmission rate when the number of class 1 active connections is 10 and the number of class 2 active connections is 15,
(B) shows that the number of active connections of class 1 is 20,
Indicates the transmission rate when the number of active connections of class 2 is 5. FIG. 14 shows the transient behavior of the Q length in the buffer of the node when the number of active connections is class 1 → 20 and class 2 → 5, and FIG. 15 shows the transient behavior of the class 1 transmission rate.

As can be seen from these figures, the ATM communication nodes of the [first embodiment] and [third embodiment] can converge the transmission rate to the target transmission rate under any of the conditions. ] (Conventional method), the combination of the number of active connections is different from that assumed, and when the number of connections of class 1 is large, the transmission rate becomes higher than the target transmission rate (see FIG. 13). As a result, congestion cannot be avoided and cell loss occurs (see FIG. 14).

[0113]

As described above, according to the present invention,
Current cell transmission rate CCR reported from each connection to node without managing state for each connection
Is normalized by the weight for each connection, the average value MACR is obtained, the transmittable rate ERQ is calculated according to the load situation applied to the node around the value, and the transmission rate ERQ is weighted and distributed to each connection. Even when connections from various negotiation parameters such as PCR and MCR are mixed, the convergence width of the MACR can be adjusted to suppress a sudden change in the MACR value, and the network bandwidth can be used efficiently. In addition, even when connections of various negotiation parameters (PCR, MCR) requested by the user are mixed, it is possible to fairly assign the weight to the bandwidth among the users.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of an ATM communication node according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a MACR calculation unit in the same ATM communication node.

FIG. 3 is a block diagram showing a configuration example of an ERQ calculation unit in the ATM communication node.

FIG. 4 is a flowchart showing a procedure of a MACR calculation process in the same ATM communication node.

FIG. 5 is a flowchart showing a procedure of an ERQ calculation process in the same ATM communication node.

FIG. 6 is a flowchart showing an ERQ writing procedure in the ATM communication node.

FIG. 7 is a flowchart illustrating a procedure of a MACR calculation process in an ATM communication node according to a third embodiment of the present invention.

FIG. 8 is a flowchart showing an ERQ writing procedure in the ATM communication node.

FIG. 9 is an ATM in the first and third embodiments of the present invention.
FIG. 4 is an explanatory diagram for describing a configuration of a model used when simulating an operation of a communication node.

FIG. 10 is a diagram showing transmission rates obtained by simulation when changing the combination of the number of active connections in the conventional transmission rate determination notification method and the transmission rate determination notification method according to the present invention.

FIG. 11 is a diagram illustrating transitional behavior of an input rate in a conventional transmission rate determination notification method and a transmission rate determination notification method according to the present invention, obtained by simulation.

FIG. 12 is a diagram illustrating transitional behavior of a transmission rate in a conventional transmission rate determination notification method and a transmission rate determination notification method according to the present invention, obtained by simulation.

FIG. 13 is a diagram showing transmission rates obtained by simulation when the combination of the number of active connections is changed in the conventional transmission rate determination notification method and the transmission rate determination notification method according to the present invention.

FIG. 14 is a diagram showing a transient behavior of a Q length in a buffer obtained by a simulation in a conventional transmission rate determination notification method and a transmission rate determination notification method according to the present invention.

FIG. 15 is a diagram illustrating transitional behavior of a transmission rate in a conventional transmission rate determination notification method and a transmission rate determination notification method according to the present invention, obtained by simulation.

[Explanation of symbols]

 Reference Signs List 1 Arrived cell number measurement unit 2 Rate calculation unit 3 Rate management unit 4 f-RM cell detection unit 5 MACR calculation unit 6 MACR management unit 7 Cell storage unit 8 Cell number management unit in buffer 9 Cell transfer unit 10 ERQ calculation unit 11 ERQ Management unit 12 b-RM cell detection unit 13 Rate writing unit 14 Weight management table 51 MACR calculation execution unit 52 State detection threshold storage unit 53 Smoothing parameter storage unit 101 ERQ calculation execution unit 102 Target input rate storage unit 103 Smooth Parameter storage

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-265333 (JP, A) JP-A-11-98142 (JP, A) JP-A-9-307557 (JP, A) JP-A-10-1998 308750 (JP, A) Ryoichi Kawahara, Hiroshi Saito, Masatoshi Kawaharazaki, Masaaki Shigetani, ABR rate control algorithm considering CR / MCR, SSE 97-56, IEICE Technical Report, July 25, 1997 ) Surveyed field (Int.Cl. ⁷ , DB name) H04L 12/56 200

Claims (11)

(57) [Claims] 1. A current transmittable rate CC used in an ATM communication network and notified from a plurality of connections.
Using the average value MACR of R, a provisional transmission available rate ERQ that temporarily determines the transmission available rate to be notified to each connection is calculated, and the transmission available rate notified to each connection is calculated based on the provisional transmission available rate ERQ. In the transmission available rate determination notification method to be determined, the weight w for each connection is managed in advance by an intra-node management table, and each time the CCR notification is received from the connection,
The MACR is updated based on the congestion state of the link and the magnitude relationship between the CCR and the ERQ so as to suppress the fluctuation of the MACR due to the CCR.
The ERQ is determined at a fixed time interval based on the above, and when the node receives an RM cell heading for the transmission side of a certain connection, the weight w for that connection is read from the intra-node management table, and A transmittable rate determination notification method, wherein a transmittable rate to be notified to a connection is finally determined, and the finally determined transmittable rate is notified to the connection. 2. A current transmittable rate CC used in an ATM communication network and notified from a plurality of connections.
Using the average value MACR of R, a provisional transmission available rate ERQ that temporarily determines the transmission available rate to be notified to each connection is calculated, and the transmission available rate notified to each connection is calculated based on the provisional transmission available rate ERQ. In the transmission available rate determination notification method to be determined, the weight w for each connection is stored in advance in the intra-node management table, and the number of arrivals Count of the cell to the link is determined by a certain measurement time interval
And the input rate to the node based on this
te is calculated, and the current cell transmission rate C from the transmission side of a connection is calculated.
When the node receives a resource management cell (hereinafter, referred to as an RM cell) in which the CR is written, the CCR value is read out, and the weight w for the connection is read out from the in-node management table, and the input rate Rate at that time is congested. If the input rate threshold value for state detection R1 is exceeded, the MACR update attenuation coefficient α is used to obtain (1−α) × MACR + α × min (MACR,
CCR / w), the MACR is updated, and if the input rate at that time does not exceed the input rate threshold R1 for detecting a congestion state, the ERQ managed in the node and a predetermined transmittable rate fluctuation absorption The value of CCR / w is compared with the value of ε × ERQ by using ε. If CCR / w> εERQ, the MACR is not updated, CCR / w ≦ εERQ, and the input rate Rate is If the input rate threshold value R2 is smaller than the non-congestion state detection input rate threshold value R2, the MACR is updated by (1−α) × MACR + α × max (MACR, CCR / w), and CCR / w ≦ εERQ and the input rate If the Rate is larger than the non-congestion state detection input rate threshold R2, the MAC is calculated by (1−α) × MACR + α × CCR / w.
Update R, whether or not the number of cells in the output waiting buffer to the link in the node exceeds a predetermined congestion detection threshold value threshold, to determine whether the link is congested or non-congested, If it is determined that the state is congested, the updated MACR
Min (β × MACR) using the input rate Rate, the rate-decay coefficient β at the time of congestion stored in advance, the rapid fluctuation suppression lower limit ERD, and the target input rate R0.
+ (1-β) × R0 / Rate × MACR, (1-ERD)
X MACR), and if the ERQ is determined to be non-congested, the updated MAC
R, the input rate Rate, a pre-stored non-congestion rate increase attenuation coefficient γ, a sudden fluctuation suppression upper limit ERU,
And using the target input rate R0, min (γ × MA
CR + (1-γ) × R0 / Rate × MACR, (1 + ER
U) × MACR) to calculate an ERQ. When the node receives an RM cell heading for the transmission side of the connection, the node reads a weight w for the connection from the intra-node management table, and reads the weight w
Transmitting a value obtained by multiplying the calculated ERQ to the RM cell as a transmittable rate and notifying the RM cell of the RM cell, and notifying the transmittable side of the RM cell. 3. The transmission available rate determination notification method according to claim 2, wherein the weight w for each connection is stored in advance in the intra-node management table,
A virtual transmission terminal installed for each connection between the transmission terminal and the node, and a weight w for the connection
And the weight w for the connection is also written in the RM cell toward the node together with the CCR. When the node receives an RM cell from the transmission side of a certain connection, the node determines the CCR from the RM cell as the CCR. Read the weight w and use it to update the MACR and ER
Q is calculated. When the node receives an RM cell toward the transmission side of the certain connection, the node reads a weight w for the connection from the RM cell, and multiplies the read weight w by the calculated ERQ. RM as the transmittable rate
A transmittable rate determination notification method, comprising writing to a cell and notifying a transmission side. 4. A current transmittable rate CC used in an ATM communication network and notified from a plurality of connections.
Using the average value MACR of R, a provisional transmission available rate ERQ that temporarily determines the transmission available rate to be notified to each connection is calculated, and the transmission available rate notified to each connection is calculated based on the provisional transmission available rate ERQ. In the transmittable rate determination notification method to be determined, the weight w for each connection is stored in advance in the intra-node management table, and the number
Is measured within a certain measurement time interval T, and based on this, an input rate Rate to the node is calculated.
When the node receives a resource management cell (hereinafter referred to as an RM cell) in which a CR and a minimum guaranteed rate MCR determined at the time of connection setting are written for the connection, the node reads out the CCR value and the MCR value and reads the connection. Is read from the intra-node management table, and when the input rate at that time exceeds the congestion state detection input rate threshold value R1, (1-α) × MACR + α using the MACR update attenuation coefficient α. × min (MACR,
(CCR-MCR) / w), the MACR is updated, and if the input rate at that time does not exceed the input rate threshold value R1 for detecting congestion, the ERQ managed in the node and a predetermined transmission Using the possible rate fluctuation absorption ε, the value of (CCR-MCR) / w is compared with the value of ε × ERQ, and if (CCR-MCR) / w> εERQ, the MAC
If R is not updated and (CCR−MCR) / w ≦ εERQ, and the input rate Rate is smaller than the input rate threshold R2 for non-congestion state detection, (1−α) × MACR + α × max ( MA
If the MACR is updated by CR, (CCR-MCR) / w), and (CCR-MCR) / w ≦ εERQ, and the input rate Rate is larger than the input rate threshold R2 for non-congestion state detection, 1−α) × MACR + α × (CCR−
MCR) / w to update the MACR according to whether the number of cells in the buffer waiting to be output to the link in the node exceeds a predetermined congestion detection threshold value threshold or not. And if it is determined that the state is congested, the updated MACR
Min (β × MACR) by using the input rate Rate, the rate-decay coefficient β for congestion rate pre-stored, the rapid fluctuation suppression lower limit ERD, and the target input rate R0 stored in advance.
+ (1-β) × R0 / Rate × MACR, (1-ERD)
X MACR), and when it is determined that the state is not congested, the updated MAC
R, the input rate Rate, a pre-stored non-congestion rate increase attenuation coefficient γ, a sudden fluctuation suppression upper limit ERU,
And using the target input rate R0, min (γ × MA
CR + (1-γ) × R0 / Rate × MACR, (1 + ER
U) × MACR) to calculate an ERQ. When the node receives an RM cell heading for the transmission side of the certain connection, the node reads out the MCR from the RM cell and sets the weight w for the connection in the in-node management table. , And the read weight w is multiplied by the calculated ERQ, and the MCR value read from the RM cell is added thereto.
A transmittable rate determination notification method, comprising writing to an M cell and notifying a transmission side. 5. The transmittable rate determination notification method according to claim 4, wherein instead of storing the weight w for each connection in the intra-node management table in advance, the transmitting terminal or
A virtual transmission terminal installed for each connection between the transmission terminal and the node, and a weight w for the connection
And the weight w for the connection is also written in the RM cell toward the node together with the CCR and the MCR. When the node receives an RM cell from a transmission side of a connection, the node transmits the RM cell from the RM cell. CCR, MC
R and weight w are read, and MACR
When the node receives an RM cell toward the transmission side of the certain connection, the node reads out a weight w for the connection from the RM cell, and calculates the calculated transmission possible with the read weight w. Multiplied by the rate ERQ, and the RM
A transmittable rate determination notification method, characterized in that a value obtained by adding an MCR value read from a cell is written to the RM cell as a transmittable rate and notified to a transmitting side. 6. The transmission available rate determination notification method according to claim 2, wherein each of the nodes, the transmission terminal, or each connection between the transmission terminal and the node is provided. In the virtual transmission terminal installed in the RM cell, instead of storing in advance the weight w for each connection, the MC written in the RM cell is used.
Using the value of R, the previously stored reference value MCR ^* of the MCR, and a parameter δ stored in advance to prevent the weight w from becoming 0 when the MCR is 0, max (M
CR, δ) / MCR ^* as the weight w of the connection, calculate the MACR and ERQ using the weight w, determine the transmittable rate based on the calculated result, and notify the transmitting side. Characteristic transmission available rate determination notification method. 7. A current transmittable rate CC used in an ATM communication network and notified from a plurality of connections.
Using the average value MACR of R, a provisional transmission available rate ERQ that temporarily determines the transmission available rate to be notified to each connection is calculated, and the transmission available rate notified to each connection is calculated based on the provisional transmission available rate ERQ. In the ATM communication node to be determined, a MACR storage unit storing the MACR, an ERQ storage unit storing the ERQ, a weight management table storing a weight w for each connection in advance, and calculating a cell input rate Rate Input rate calculating means, detecting means for detecting a CCR from a resource management cell (hereinafter referred to as an RM cell) transmitted from the transmitting side of the plurality of connections, and when the detecting means detects a CCR, the CCR is detected. Reads the weight w for the transmitted connection from the weight management table MACR updating means for updating the MACR stored in the MACR storage means based on the value of the CCR and the read weight w, determining whether the link is in a congested state or a non-congested state, An ER that updates the ERQ stored in the ERQ storage means based on the MACR stored in the MACR storage means and a predetermined parameter according to the determination result.
Q updating means, when the node receives an RM cell destined for the transmission side of each connection, reads a weight w for the connection to which the RM cell is directed from the weight management table, and reads the read weight w and the weight w An ATM communication node comprising: a writing unit that writes a transmittable rate determined based on an ERQ stored in an updated ERQ storage unit into the RM cell and notifies a transmission side of the RM cell. 8. The congestion state detection input rate threshold value R1 for judging that a link is in a congestion state, and a non-congestion state for judging that a link is in a non-congestion state. Input rate threshold R for detection
2. a MACR update decay coefficient α that determines how much the detected CCR is reflected in the MACR;
A first storage unit for storing a transmittable rate fluctuation absorption parameter ε for determining whether or not to add the detected CCR value to the MACR; and when the CCR is detected by the detection unit, Read the weight w for the connection to which the CCR was sent from the intra-node management table. If the input rate at that time exceeds the congestion state detection input rate threshold value R1, the MACR update attenuation count α Using (1-
α) × MACR + α × min (MACR, CCR / w), and if the input rate Rate does not exceed the congestion state detection input rate threshold value R1,
Using the ERQ stored in the RQ storage means and the transmittable rate fluctuation absorption parameter ε, the value of CCR / w is compared with the value of ε × ERQ, and if CCR / w> εERQ, the MACR is Not updated, CCR / w ≦ εERQ
And when the input rate Rate is smaller than the non-congestion state detection input rate threshold value R2, (1−α) ×
MACR + α × max (MACR, CCR / w)
When the CR is updated and CCR / w ≦ εERQ and the input rate Rate is larger than the non-congestion state detection input rate threshold value R2, (1−α) × MACR + α × CCR /
8. The MACR is updated by w.
An ATM communication node according to claim 1. 9. A current transmittable rate CC used in an ATM communication network and notified from a plurality of connections.
Using the average value MACR of R, a provisional transmission available rate ERQ that temporarily determines the transmission available rate to be notified to each connection is calculated, and the transmission available rate notified to each connection is calculated based on the provisional transmission available rate ERQ. In the ATM communication node to be determined, a MACR storage unit storing the MACR, an ERQ storage unit storing the ERQ, a weight management table storing a weight w for each connection in advance, and calculating a cell input rate Rate An input rate calculating means, a CCR from a resource management cell (hereinafter referred to as an RM cell) transmitted from a transmitting side of the plurality of connections, and a minimum guarantee determined at the time of connection setting for the connection to which the RM cell is transmitted. Detecting means for detecting the rate MCR; And MC
When R is detected, the weight w for the connection from which the CCR and MCR have been transmitted is read from the weight management table, and stored in the MACR storage means based on the values of the CCR and MCR and the read weight w. MACR updating means for updating the calculated MACR, determining whether the link is in a congested state or a non-congested state, and determining the MACR stored in the MACR storage means according to the determination result; ER that updates the ERQ stored in the ERQ storage means based on
Q updating means, when the node receives an RM cell destined for the transmission side of each connection, reads a weight w for the connection to which the RM cell is directed from the weight management table, and reads the read weight w and the weight w ATM communication characterized by comprising writing means for writing the transmittable rate determined based on the MCR and the ERQ stored in the updated ERQ storage means to the RM cell, and notifying the transmission side of the RM cell. node. 10. The MACR updating means includes: a congestion state detection input rate threshold value R1 for determining that a link is in a congestion state; and a non-congestion state for determining that a link is in a non-congestion state. Input rate threshold R2 for detection, how much the detected CCR is MAC
A first storage storing a MACR update attenuation coefficient α for determining whether to reflect the value on R, and a transmittable rate fluctuation absorption parameter ε for determining whether to add the detected CCR value to MACR. When a CCR and an MCR are detected by the detecting means, a weight w for the connection to which the CCR is sent is read from the intra-node management table, and an input rate at that time is used for detecting the congestion state. Input rate threshold R
If it exceeds 1, the MACR update attenuation coefficient α is used to obtain (1−α) × MACR + α × min (MACR, (C
CR-MCR) / w), if the input rate Rate does not exceed the congestion state detection input rate threshold value R1, the ERQ stored in the ERQ storage means and the transmittable rate fluctuation Using the absorption parameter ε, the value of (CCR-MCR) / w is compared with the value of ε × ERQ. If (CCR-MCR) / w> εERQ, the MACR is not updated, and (CCR- MCR) / w ≦
If εERQ and the input rate Rate is smaller than the non-congestion state detection input rate threshold value R2, (1
−α) × MACR + α × max (MACR, (CCR-MC
R) / w) to update the MACR and (CCR-MC
R) / w ≦ εERQ, and if the input rate Rate is larger than the non-congestion state detection input rate threshold value R2, the MACR is updated by (1−α) × MACR + α × (CCR-MCR) / w. The ATM communication node according to claim 9, wherein: 11. The ERQ updating means, wherein the target input rate R0, a predetermined rate decrease attenuation coefficient β used for calculating the ERQ when it is determined that the link is congested, and an ERQ An abrupt fluctuation suppression lower limit value ERD, which is a parameter for suppressing the change from becoming sufficiently small, and a predetermined rate increase attenuation coefficient γ used when calculating the ERQ when it is determined that the link is in a non-congested state. And a sudden fluctuation suppression upper limit ER which is a parameter for suppressing ERQ from becoming excessively large.
U and a second storage means for storing U, when the congestion state is determined, the MACR, the input rate Rate, the congestion rate reduction attenuation coefficient β, the rapid fluctuation suppression lower limit ERD, and Using the target input rate R0, mi
n (β × MACR + (1−β) × R0 / Rate × MAC
R, (1−ERD) × MACR), and updates the provisional transmittable rate ERQ.
R, the input rate Rate, a pre-stored non-congestion rate increase attenuation coefficient γ, a sudden fluctuation suppression upper limit ERU,
And using the target input rate R0, min (γ × MA
CR + (1-γ) × R0 / Rate × MACR, (1 + ER
The ATM communication node according to any one of claims 7 to 10, wherein the provisional transmission available rate ERQ is updated by (U) x MACR).