JP2000261434A - Method and system for variable queue length control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent transmission characteristic by setting a threshold strictly. SOLUTION: In the case that queue information with respect to respective queues is fetched from a queue length measurement section 8 in this variable queue length control method, an output queue decision section 9 receives a notice of a queue number to output an output queue. Variable threshold control is a processing among a plurality of queues with respect to a same output port and this threshold has information that is used to discriminate to which of output ports 1-4 the queue number received in advance from the output queue decision section 9 belongs or whether or not an optional queue belongs to the output port. In the variable threshold processing, a threshold, before the queue length information is revised by an output of the queue number from the output queue decision section 9 where the queue length information received from the queue length measurement section 8 is used for a processing trigger, is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable queue length control method and apparatus for performing queue length management for limiting an output band in a switch (circuit switching) process and a shaping process in a communication network with a variable threshold value. With regard to
In particular, the threshold set for each queue is set to the required value when only that queue exists for the output port, and the threshold set for interference by other queue-accommodated traffic may be changed as needed. And a variable queue length control method and apparatus for changing the variable queue length.

[0002]

2. Description of the Related Art Recently, for example, TCP / IP (Transm
ission Control Protocol / Internet Protocol)
P packet communication network and broadband (B) IS
ATM (Asynchtra) for multimedia such as DN
(sfer mode / asynchronous transfer mode) In a switch (circuit switching) or shaping processing in a communication network, input data is transmitted in connection units or service quality (Qos / Quality of service) in order to limit an output band.
e) Queuing is performed in units (service units) and the queue length management control is performed. Hereinafter, only the ATM communication will be described.

The ATM communication system uses a synchronous digital hierarchy (SDH / Synchronous) applied to B-ISDN or the like.
ous Digital Hierarchy) The connection setting for the output link is statistically multiplexed as compared with communication that secures a transmission band for each connection such as a communication system.
Therefore, in the ATM communication system, although the bandwidth utilization rate in the entire communication network is improved, ATM cells are discarded due to congestion between connections due to the statistical multiplexing process.

An apparatus for performing such queue management control includes:
For example, queue management control is performed once for each output port, connection and service quality (Qos) unit obtained by multiplexing and demultiplexing an input signal to be multiplexed, and an output queue is determined according to the bandwidth of the output port and the queuing situation. are doing. Then, the head cell of the corresponding queue is read at a predetermined timing and transmitted to the corresponding output port.

In the queue management control in this case, the threshold is set in advance so as to correspond to the delay characteristic and the discard characteristic, and control is performed to discard the arriving cell. In this threshold setting, it is necessary to consider relatively complicated congestion between queues to be output from a plurality of output ports, and thus it is difficult to set a strict threshold. In other words, as described above, AT
M cells will be discarded.

In such queue management control, various proposals have been made for the configuration and processing. For example, JP-A-61-232744, "Buffer management system"
According to the conventional example, when the number of allocations to the reception buffer and the transmission queue length are dynamically changed in accordance with the number of empty buffers, when a line device or the like having a severe time condition from reception of information to transmission is connected. The data transmission / reception is performed while suppressing an increase in the delay time. Further, Japanese Patent Application Laid-Open No. 4-34653
In the conventional example of No. 9, "route queue length control method", small-sized and simple software is used for route queue length control for keeping the number of stored packets in a queue for storing packets for each transmission route to a certain value or less. And the routing control adapted to the change of the outgoing line state.

[0007]

However, in the above-mentioned conventional example, setting of a threshold value in queue management control for guaranteeing transmission characteristics has the following problems.
There is a need for a communication network that improves transmission characteristics due to TM cell discard.

(1) In the setting of the threshold value as described above, it is necessary to find an average use bandwidth ratio (utilization rate) to a bandwidth of a queue corresponding to an output link bandwidth. For the calculation of the bandwidth of the corresponding queue, all pieces of traffic information to be accommodated in other queues are required. In other words, it is difficult to set by calculating the optimum threshold value.

(2) For the same reason as the problem pointed out in (1) above, it is necessary to change the threshold value for each change in the traffic characteristics of another queue accommodating due to the change of the connection setting accommodated in another queue. There is. In this case, it is difficult to set an optimal threshold.

(3) For the same reason as the problem pointed out in the above (1), when the threshold value is set to be larger than the value required for obtaining the characteristic in setting the threshold value, Therefore, the utilization rate of a high band, which is an advantage of the ATM communication system, is reduced.

The present invention solves such a problem in the prior art, and sets a threshold value set for each queue when only that queue is present at an output port.
By setting the required value, the interference caused by other queued traffic can be changed at any time from the set threshold value, so that a more strict threshold value can be set, resulting in good transmission. It is an object of the present invention to provide a variable queue length control method and device capable of obtaining characteristics.

[0012]

In order to achieve the above object, a variable queue length control method according to the present invention discards an arriving cell by using a variable threshold. The process of changing the setting to a value corresponding to the bandwidth characteristics of each output port of the queue and not considering the traffic characteristics of other queues, and dynamically based on the queue length and the set threshold Variably determining a variable threshold.

In the process of variably determining the variable threshold value, when a cell is output from a queue other than the target queue, and the buffer accumulation queue length is smaller than a value obtained by subtracting the set threshold value from the variable threshold value. If it is larger, it is added to the variable threshold, and at the time of cell output from the target queue, and
If the value obtained by subtracting the buffer accumulation queue length from the variable threshold is equal to or greater than the set threshold, the variable threshold is subtracted.

Further, when two types of cells are queued in one queue, storage judgment of the queue is individually performed, and threshold and queue length management control are individually performed on the two types of cells. are doing.

According to the variable queue length control device of the present invention, the arriving cell is discarded by a variable threshold value.
Queue management control is performed on the input signal at least for each unit of output port, connection, and service quality, and further, an output queue is determined according to at least the bandwidth of the output port and the queuing state, and the head cell of the corresponding queue is determined at a predetermined timing. And the switch processing means for reading out and sending out to the corresponding output port, and setting the variable threshold value to a value corresponding to the band characteristic of each output port of the queue, and a value not considering traffic characteristics of other queues And a variable threshold value setting processing means for dynamically varying the queue length and the set threshold value to determine the variable threshold value.

When the variable threshold setting processing means outputs a cell from a queue other than the target queue and the buffer accumulation queue length is larger than a value obtained by subtracting the set threshold from the variable threshold. , When the cell is output from the target queue and the value obtained by subtracting the buffer accumulation queue length from the variable threshold is equal to or greater than the set threshold, And a variable threshold value is set by subtraction.

Further, when two types of cells are queued in one queue, the switch processing means and the variable threshold value setting processing means individually determine the storage of the queues, and perform two types of cell determination. , The threshold and queue length management control are individually executed.

Further, the switch processing means and the variable threshold setting processing means include a multiplexing unit for multiplexing the data unit from the input port in cell units, an input port number, an output port number from the cell header information, A cell information extraction unit that extracts cell information that determines information necessary for circuit switching of service quality information, a cell discard unit that sends out data discarding cell information and switch processing information, and queuing for each of the queues. A buffer unit for transmitting a state change of each queue read from the queue, a separation unit for separating the output for each cell unit, and a threshold value information for all the queues,
A threshold setting unit for transmitting variable threshold information with the set threshold information as an initial value; queue length information of a queue to be queued by switch processing information; and variable threshold information for the queue A cell discard determination unit that notifies when the corresponding queue is a variable threshold of “queue length ≧ applicable queue”, a queue length measurement unit that measures the queue length for all held queues,
An output queue determining unit for determining a queue to be output based on queue length information for each of the queues and output queue determination logic information preset as switch processing characteristics is provided.

Also, the variable queue length control device described above is
The configuration is applied to an ATM cell communication network or an IP packet communication network.

As described above, in the variable queue length control method and apparatus according to the present invention, according to the queue management control conventionally performed, the cell arriving by the threshold value set in advance to satisfy the delay characteristic and the discard characteristic is determined. Has been discarded. That is, the input signal is output to the output port, connection,
Performs queue management control for each unit of service quality, then determines an output queue according to the bandwidth of the output port and the queuing status, reads the head cell of the queue at a predetermined timing, and sends it to the output port. .

On the other hand, in the present invention, the threshold value is set to a value corresponding to the band characteristic of each output port of each queue, and the setting is changed to a value that does not take into account the traffic characteristics of other queues. Then, the threshold (variable threshold) used for the queue length management control is dynamically varied from the cell output from the set threshold and the relationship between the queue length and the set threshold at that time. I have decided.

In the specific example, the variable threshold value of an arbitrary queue among a plurality of queues output to the same output port has a threshold value set as an initial value. And
At the time of cell output from a queue other than the target queue, and when the buffer accumulation queue length is larger than a value obtained by subtracting the set threshold from the variable threshold, for example, 1 is added to the variable threshold. ing. Further, at the time of outputting a cell from the target queue, and when the value obtained by subtracting the buffer accumulation queue length from the variable threshold is equal to or larger than the set threshold, for example, 1 is subtracted from the variable threshold. I have.

Thus, in this variable queue length control,
The set threshold value for each queue is set to a value required when only that queue is present at the output port, and the interference from other queue-accommodated traffic can be changed at any time from the set threshold value. As a result, a more strict threshold value can be set, and good transmission characteristics can be obtained.

Further, the variable queue length control method and apparatus of the present invention, when two types of cells are queued in one queue, individually determine the storage of the queue,
The threshold and queue length management control are individually executed for the two types of cells.

As a result, when it is difficult to realize queuing with a plurality of queues, or when it is difficult to determine the output queue when a plurality of queues are provided, only a plurality of traffic managements accommodating the queues are required. It is possible to suppress interference between the traffics that perform the management.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a variable queue length control method and apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration according to an embodiment of a variable queue length control method and device thereof according to the present invention. In FIG. 1, the variable queue length control device includes a multiplexing unit 1 that performs a multiplexing process using a data unit input to an input port (1, 2, 3, 4) as a cell unit, an input port number, and a cell header. Output port number and Qo from information
a cell information extraction unit 2 for extracting cell information for determining information necessary for switch (circuit switching) processing such as s information.

The variable queue length control device includes a cell discarding unit 3 for transmitting data obtained by discarding cell information and switch processing information from the cell information extracting unit 2, queuing to each queue, and reading from the queue. A buffer unit 4 for transmitting the status change of each queue at any time, a separating unit 5 for separating and transmitting to a predetermined output port (1, 2, 3, 4) for each cell, and setting for all queues. A threshold setting unit 6 for sending threshold information and variable threshold information with the set threshold information as an initial value.

Further, the variable queue length control device fetches the queue length information of the queue to be queued based on the switch processing information determined by the cell information extracting unit 2 and the variable threshold information for the corresponding queue, and Has a cell discard determination unit 7 for notifying when the variable threshold value is “queue length ≧ applicable queue”. Further, a queue length measuring unit 8 that manages queue length information for all held queues, and queue length information on each queue from the queue length measuring unit 8 and determination of an output queue preset as a switch processing characteristic An output queue determining unit for determining a queue to be output based on the logical information;

Next, the operation of this embodiment will be described. The data input to the input ports (1 to 4) is input to the multiplexing unit 1. The multiplexing unit 1 performs a multiplexing process using a data unit as a cell unit, and the multiplexed data is input to the cell information extracting unit 2. In the cell information extraction unit 2,
Information necessary for switch processing, such as an output port number and QoS information, is determined from the input port number and the cell header information. Based on the switch processing information determined by the cell information extraction unit 2, the cell discard determination unit 7 fetches queue length information for the queue to be queued from the queue length measurement unit 8. Further, the cell discard determination unit 7 fetches variable threshold information for the corresponding queue from the threshold setting unit 6 and, when the corresponding queue has a variable threshold of “queue length ≧ applicable queue”, The notification is sent to the cell discarding unit 3.

The cell discarding unit 3 sends the data obtained by discarding the cell information and the switch processing information from the cell information extracting unit 2 to the buffer unit 4. The buffer unit 4 performs queuing on an input cell (data) not discarded by the cell discarding unit 3 in a queue determined by switch information of the cell. The buffer unit 4 reads cells from the corresponding queue based on the queue number from the output queue determining unit 9. The separation unit 5 separates and sends the output to predetermined output ports (1 to 4) for each cell.

The buffer unit 4 also notifies the queue length measuring unit 8 of changes in the status of each queue due to the queuing of each queue and the process of reading from each queue. The queue length measuring unit 8 manages queue length information for all held queues. The output queue determining unit 9 determines a queue to be output based on the queue length information of each queue from the queue length measuring unit 8 and the output logic of the output queue which is set in advance as a switch process. Notify the buffer unit 4.

As described above, the switching process is performed by the operation from the multiplexing unit 1 to the output queue determining unit 9.

Next, the operation of determining the variable threshold will be described in detail. The threshold in the threshold setting unit 6 in FIG. 1 has set threshold information for all queues and variable threshold information with the set threshold information as an initial value. Also, when the queue information of each queue is input from the queue length measuring unit 8, the threshold setting unit 6 receives a notification of the queue number output by the output queue determining unit 9.

The variable threshold control using the threshold in the threshold setting unit 6 is a process between a plurality of queues for the same output port. For this reason, the threshold value is determined in advance by the queue number that has received the notification from the output queue determining unit 9.
Which of the output ports (1 to 4) or an arbitrary queue has information that can be used to determine which of the output ports (1 to 4) belongs. Further, the processing by the variable threshold using the threshold in the threshold setting unit 6 is as follows.
The queue length information from the queue length measurement unit 8 used for the variable threshold value processing is used as the value before the queue length information is changed by the output of the queue number from the output queue determination unit 9 serving as a processing trigger.

FIG. 2 is a flowchart for explaining the variable threshold processing for each queue. 1 and 2
, The variable threshold information Qth1 has set threshold information Qth1_def1 as an initial value, and the notified output queue number belongs to the own queue number or the output port to which the own queue is to be output. If it is a queue, it will be processed. Conversely, in the output queue number notification in which the own queue does not belong to the output port to be output, the processing is not performed, and the variable threshold does not change.

The notified output queue number is another queue number belonging to the output port to be output of the own queue, and the input queue length information is “variable threshold value−set threshold value”. If greater, set the variable threshold to 1
Is added (routine process 1 in FIG. 2), and otherwise the variable threshold is not changed (routine process 2 in FIG. 2).
The notified output queue number is the own queue number, and when “variable threshold value−buffer accumulation queue length” is equal to or larger than the set threshold value, the variable threshold value is subtracted by 1 (see FIG. 2). In other cases, the variable threshold is not changed (routine process 4 in FIG. 2).

FIG. 3 is a diagram for explaining the operation of the variable threshold value process. Processes 1, 2, 3, and 4 in the operation of the variable threshold value process correspond to the routine processes 1 to 4 shown in FIG.
e) The variable threshold value processing state for number 1 is shown. Note that the queue (Queue) number 2 corresponds to the queue (Q
Queue) This is a case where another queue belonging to the output port to be output with the number 1 is output. Queue
e) The set threshold value (Qth1_def1), which is the initial value of the variable threshold value (Qth1) of No. 1, is based on the output link bandwidth determined by the rate at which the output port to which the own queue belongs as an output cell is determined. When the output port to which the own queue belongs to the output cell is determined, the value necessary for acquiring the characteristics of the own queue is set as the determination of the own queue.

In process 1 in FIG. 3, the queue (Qucu)
e) No. 2 is selected as the output queue, and the output is not performed even though a cell that can be output is stored in queue (Queue) number 1. As a result, the queue length (Qlen1) does not decrease. This is an operation for maintaining the proof stress by increasing the variable threshold value (Qth1) because the buffer amount secured by the threshold necessary for acquiring the characteristics of the input cell, that is, 1 in the proof stress decreases. is there.

In the process 2 in FIG. 3, the queue (Queue) number 2 is selected as the output as in the process 1 described above, but the variable threshold (Qth1) is
en1), it has a set threshold value (Qth1_def1) as a cell-unstored area, and has a sufficient proof stress without reducing the queue length (Qlen1) by reading. Therefore, the variable threshold value (Qth1) is not changed.

In process 4 in FIG. 3, a queue (Qucu
e) Number 1 is selected as the output queue, and the cell end storage area obtained by subtracting the queue length (Qlen1) from the variable threshold (Qth1) is the set threshold (Qth1_def).
1) It has no minutes. Therefore, the variable threshold (Qth1) is not changed so that the proof stress by the cell output increases by one.

In the process 3 in FIG. 3, the queue (Queue) number 1 is selected as the output queue as in the process 4, but the queue length (Qlen1) is subtracted from the variable threshold (Qth1). This is a state where the cell end storage area has the set threshold value (Qth1_def1). That is, since the proof stress is more than necessary by the cell output, 1 is subtracted from the variable threshold value (Qth1), and the proof stress of the set threshold value (Qth1_def1) is obtained.
The maintenance operation is performed.

In other words, as a whole operation, the variable threshold value (Qth1) is equal to the set threshold value (Qt
h1_def1), the proof strength of the set threshold value (Qth1_def1) is secured for reading the queue (Queue) number 1,
This is an operation that makes a transition in a direction to reduce unnecessary proof stress.

FIG. 4 is a diagram for explaining another embodiment. In FIG. 4, two types of cells are queued in one queue. Here, the storage determination of the queue is individually performed. Therefore, the threshold and the queue length are separately managed and controlled for the two types of cells. This is because when it is difficult to implement queuing with a plurality of queues, or when it is difficult to determine the output queue when there are multiple queues, only a plurality of traffic managements containing queues are used to manage the queues. This is to suppress interference between traffics to be performed. Also in this case, by applying the variable queue length control of the above-described embodiment, the same advantages as those of the above-described embodiment can be obtained. That is, the above-mentioned problem can be solved.

Next, the operation of the embodiment of the present invention will be summarized and described. FIG. 5 is a diagram for explaining an operation summary of the embodiment of the present invention, and FIG. 6 is a diagram for explaining another operation summary of the embodiment of the present invention. In case 1 shown in FIG. 5, only one queue is provided for the output port. The setting of the threshold value in this case is determined by the ratio of the input link band to the output link band, the traffic characteristics to be accommodated in the queue, and the average use band ratio (use rate) to the output link band. One of them is a content based on a physical configuration, and the other is information on traffic accommodated in a queue.

On the other hand, in case 2 shown in FIG. 6, two queues are provided for the output port. That is, this is an example in which selection output is performed based on an arbitrary reference. In this case, the setting of the threshold value requires that an average utilization bandwidth ratio (utilization rate = ρ) to a virtual link bandwidth (Virtual Link Band Wide) of the corresponding queue with respect to the output link bandwidth be required. In order to calculate the bandwidth of the corresponding queue, all information on the traffic accommodated in another queue is required.

As a result, as described in the prior art,
It becomes difficult to set an optimum threshold value, and a threshold value must be changed each time another queue-accommodated traffic characteristic is changed due to a change in another queue-accommodated connection setting. Also,
When the threshold value is set to a value larger than the value required for acquiring the characteristics, a higher bandwidth utilization rate, which is an advantage of the ATM communication system, is obtained, and the utilization rate decreases.

On the other hand, in the embodiment of the present invention, the threshold value of each queue can be set only by information on the traffic accommodated in the target queue. That is, after setting the set threshold value to a value derived in the form of case 1 shown in FIG.
As described in the case 2 shown in FIG.

[0048]

As is apparent from the above description, according to the variable queue length control method and apparatus of the present invention, the threshold value set for each queue is determined when only that queue exists for the output port. From the set threshold for interference with other queued traffic,
It can be changed at any time. As a result, the threshold value can be set more strictly, and good transmission characteristics can be obtained.

Further, according to the variable queue length control method and apparatus of the present invention, when two types of cells are queued in one queue, the storage determination of the queue is individually performed, and the two types of cells are queued. The threshold and the queue length management control are individually executed for the cells. As a result, it is possible to suppress interference between the traffics to be managed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a variable queue length control method and apparatus according to the present invention.

FIG. 2 is a flowchart for explaining variable threshold processing for a queue in the embodiment.

FIG. 3 is a diagram illustrating an operation of a variable threshold value process in the embodiment.

FIG. 4 is a diagram for explaining another embodiment.

FIG. 5 is a diagram for describing an operation summary in the embodiment.

FIG. 6 is a diagram illustrating a summary of another operation in the embodiment.

[Explanation of symbols]

 Reference Signs List 1 multiplexing unit 2 cell information extracting unit 3 cell discarding unit 4 buffer unit 5 separating unit 6 threshold setting unit 7 cell discarding judging unit 8 queue length measuring unit 9 output queue determining unit

Claims (8)

[Claims] 1. A variable queue length control method for discarding an arriving cell using a variable threshold value, wherein the variable threshold value is set to a value corresponding to a band characteristic of each output port of the queue, and Changing the setting to a value that does not take into account the traffic characteristics of other queues, and dynamically determining a variable threshold based on the queue length and the set threshold. And a variable queue length control method. 2. The method according to claim 1, further comprising the steps of: when outputting a cell from a queue other than the target queue, and when the buffer accumulation queue length is larger than a value obtained by subtracting the set threshold from the variable threshold. When the cell is output from the target queue and the value obtained by subtracting the buffer accumulation queue length from the variable threshold is equal to or greater than the set threshold, 2. The variable queue length control method according to claim 1, wherein the subtraction is performed. 3. When two types of cells are queued in the one queue, storage determination of the queue is individually performed, and threshold value and queue length management control are individually performed on the two types of cells. 3. The method according to claim 1, wherein the step is executed.
The variable queue length control method described in the above. 4. A variable queue length control device for discarding an arriving cell by using a variable threshold value, wherein the input signal is subjected to queue management control at least for each output port, connection, and unit of service quality. A switch processing means for determining an output queue according to the bandwidth of the output port and the queuing state, reading a head cell of the corresponding queue at a predetermined timing, and transmitting the read cell to the corresponding output port; Values that correspond to the bandwidth characteristics of each output port, and change the setting to a value that does not take into account the traffic characteristics of other queues. And a variable threshold value setting processing means for variably determining a variable threshold value. 5. The variable threshold value setting means, when outputting a cell from a queue other than the target queue, and wherein the buffer accumulation queue length is larger than a value obtained by subtracting the set threshold value from the variable threshold value. Variable threshold value, and when the cell is output from the target queue, and the value obtained by subtracting the buffer accumulation queue length from the variable threshold value is equal to or greater than the set threshold value, the variable threshold value 5. The variable queue length control device according to claim 4, wherein a variable threshold value is set by subtracting the variable queue length from the threshold value. 6. When two types of cells are queued in one queue, the switch processing unit and the variable threshold value setting processing unit individually determine the storage of the queue, and 6. The variable queue length control device according to claim 4, wherein threshold value and queue length management control are individually performed on the variable queue length control device. 7. A multiplexing unit for multiplexing a data unit from an input port in cell units as the switch processing unit and the variable threshold value setting processing unit, an input port number, an output port number from cell header information, A cell information extraction unit that extracts cell information that determines information necessary for circuit switching of service quality information, a cell discard unit that sends data discarding cell information and switch processing information, and queuing for each of the queues. A buffer unit that sends out the status change of each queue read from the queue, a separating unit that separates out each cell unit and sends it to the output port, setting threshold information for all queues, and setting threshold information Threshold setting unit that sends variable threshold information with the initial value of queuing, and queuing by switch processing information A cell discard determination unit that fetches queue length information of a queue to be performed and variable threshold information for the queue, and notifies when the queue is a variable threshold of “queue length ≧ applicable queue”; A queue length measuring unit for measuring the queue length of all queues to be executed, and a queue to be output based on queue length information for each of the queues and output queue determination logic information set in advance as switch processing characteristics. The variable queue length control device according to claim 4, further comprising: an output queue determination unit. 8. A variable queue length control device according to claim 4, wherein the variable queue length control device is applied to an ATM cell communication network or an IP packet communication network.