JPH1132050A - Method for controlling priority control queue in atm exchanging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a queue control method in an ATM exchanging device, in which communication quality can be improved in heavier traffic than those in exchanging devices having queues with the same capacity by effectively utilizing resources in the exchanging device. SOLUTION: This method controls queues of an ATM exchanging device having plural queues for each priority class, and at the time of registering queues for a cell received by a line interface part based on steps 301-312, the requirement of queues corresponding to the priory class is monitored (304). Then, when the requirement of the required priority class queues of a VC (logical communication connection) exceeds a certain constant amount, a management pointer for each priority class is changed (307) for temporarily and dynamically assigning the constant amount of unused queues from the other priority class queues as the required priority class queues of the VC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM (Asynchro
nous Transfer Mode: In a communication network using switching technology, when requesting communication quality for each type of traffic such as data, voice, image, etc., multiple The present invention relates to a technique effective when applied to a queue control method in an ATM switching device having a priority control queue (hereinafter, simply referred to as a queue).

[0002]

2. Description of the Related Art For example, according to the study by the present inventor, in an ATM switching device constituting an ATM network, an ATM Forum UNI 3.0 / 3.1,
In order to realize the QoS (Quality of Service) class specified in 4.0, CBR (Constant Bit Rate), VBR
(Variable Bit Rate), ABR (Available Bit Rat)
e) A queue corresponding to a priority class required by each logical communication connection (hereinafter referred to as VC) is fixedly assigned to a plurality of queues for each priority class such as an UBR (Unspecified Bit Rate), and an ATM cell (hereinafter referred to as an ATM cell). A technique for performing cell transfer (hereinafter, simply referred to as a cell) is known.

[0003] As a technique related to such an ATM switching apparatus, for example, "ATM-LAN" P111-111 issued by Soft Research Center on February 10, 1995.
The technology described in P127 is exemplified.

[0004]

By the way, in the above-described ATM switching apparatus, when traffic is concentrated in one priority class, the amount of use of a queue corresponding to this class becomes high, and a cell is discarded to cause communication. There is a risk that the quality will decrease. Further, in such a case, even when a queue corresponding to another priority class is not used, the queue in the priority class requested by the VC is fixedly allocated, so that the resources in the ATM switching device are effectively used. Not available.

That is, in the above ATM switching device technology, a queue corresponding to a priority class requested by a VC is fixedly used, so that unused VCs are effectively used to increase the number of VCs. A problem that cannot be transferred is considered.

Accordingly, an object of the present invention is to monitor the queue usage in an ATM switching device having a plurality of queues for each priority class, and to determine the queue corresponding to the priority class requested by each VC according to the status of use of the queue. Can dynamically utilize the resources in the ATM switching device by dynamically changing the quota of the ATM, and improve the communication quality for more traffic than the switching device having the queue of the same capacity.
An object of the present invention is to provide a queue control method in a switching device.

[0007]

To solve the above-mentioned problems, a queue control method in an ATM switching apparatus according to the present invention uses a plurality of queues corresponding to priority classes in an ATM switching apparatus having a queue for each priority class. By monitoring the amount and dynamically changing the queue allocation corresponding to the priority class requested by the VC at the time of cell transfer, effective use of resources is achieved. This enables more traffic to be transferred as compared with.

[0008] As a specific example, a queue control method capable of improving the efficiency of using limited resources in an ATM switching device and further efficiently setting a larger number of VCs by further reducing the cell discard rate is described in each prior art. A function to dynamically change the management pointer that controls the queue allocation amount for each class is provided, and the queue size corresponding to each priority class can be changed, so that the traffic class increases and the queue usage increases. A function to temporarily allocate a certain amount of unused queues corresponding to other priority classes with low queue usage, and to return queues to priority classes with a small queue size when queue usage is low Is provided.

That is, when a queue for a cell received by the line interface unit is registered, if the usage of the request priority class queue of the VC exceeds a certain amount,
Efficient use of resources in the ATM switching equipment by changing the management pointer for each priority class to temporarily allocate a certain amount of unused queues from other priority class queues as request priority class queues for the VC. In addition, the cell discard rate can be further reduced to more efficiently guarantee communication quality.

[0010] As another specific example, it is possible to improve the use efficiency of limited resources in the ATM switching device, reduce the cell discard rate, and efficiently set more VCs, and to increase the number of cells on the line. The queue control method which can prevent the order inversion from occurring in the unit of cell when transmitting a frame is provided with a function of recognizing a frame for each VC, and a priority class required by a certain VC (hereinafter referred to as a request priority class). ), The usage of the queue corresponding to each priority class is changed to a priority class having a higher priority and a lower queue usage (hereinafter referred to as a high priority class). When changing the queue size corresponding to the request priority class apparently from the line interface by changing to the original request priority class according to It is obtained to perform a frame-by-frame basis of the VC.

That is, when a queue is registered for a cell received by the line interface unit, if the usage of the request priority class queue exceeds a certain amount, the priority of the queue is higher than that of the request priority class. By changing to a high-priority class with low volume or changing to the original request priority class in frame units according to queue usage,
It is possible to effectively utilize resources in the ATM switching apparatus, further reduce the cell discard rate, and more efficiently guarantee communication quality.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic configuration diagram showing an ATM switching apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a diagram showing a case where a queue size is changed in the ATM switching apparatus according to Embodiment 1 of the present invention. FIG. 3 is a flowchart showing processing for changing the queue size.

First, FIG. 1 shows an ATM according to the first embodiment.
The schematic configuration of the switching device will be described.

The ATM switching apparatus according to the first embodiment is, for example, an ATM switching apparatus 1 having a plurality of queues for each priority class, and includes a cell switch section 2 and line interface sections 51 to 55. Cell switch unit 2
Is a queue for each priority class, and a cell transfer for registering the queues 31 to 34 when transmitting cells on each VC from the line interface units 51 to 55 accommodating the ATM network to the cell switch unit 2. A mechanism 41 for processing the queues 31 to 34 and transmitting cells to the line interface units 51 to 55 in accordance with the priority order;
And are provided.

The queues 31 to 34 are denoted by 31, 32, 33 and 34 in descending order of priority. Hereinafter, when a priority class is represented, the priority class of the queue 31 is denoted by the same code as "priority class 31". Shall be treated. Also, as shown in FIG. 2 described later, the cell transfer mechanisms 41 and 42 have
A frame recognition function 7 for recognizing each frame, a buffer 8 for temporarily storing cells, and the like are provided.

Here, the outline of changing the queue size will be described with reference to FIG.

FIG. 2 shows, as an example, the queue usage in the queue 33 specified by two management pointers 631 and 632 for controlling the queue allocation amount, and the queue 34 specified by the management pointers 641 and 642. A fixed amount of unused queues designated by the management pointers 632 and 633 from a queue 33 with a low queue
4, the queue 33 becomes the management pointers 631 and 633, and the queue 34 becomes the management pointer 64.
1 and 643 show a structure changed to the queue size specified respectively.

A certain amount of queue designated by the management pointers 632 and 633 is used when the usage of the queue 34 becomes low and queues corresponding to other priority classes become insufficient, or when the usage of the queue 33 of the allocation source becomes insufficient. Becomes higher and the original queue size is required, the queue usage is monitored, and the queue is dynamically allocated from the low priority class to the high priority class.

Next, the ATM switching device 1 of the first embodiment
With regard to the queue control method described above, a processing procedure for changing the queue size will be described with reference to FIG.

According to the queue control method shown in FIG. 3, when the queue usage of the VC request priority class is high in accordance with the queue usage, a certain amount of unused queues corresponding to the priority classes with low queue usage are removed. This implements a process of temporarily assigning a queue to the request priority class of the VC.

For example, a VC that sets a request priority class having a high queue usage to a priority class 34 may assign a certain amount of unused queues to the priority class 33 having a low queue usage to the queue 34.
, Cell transfer of the VC is enabled.

In this queue control method, first, cells on the VC requesting the priority class 34 received by the line interface unit 51 (52 to 55) are sent to the cell transfer unit 41 (steps 301 and 302). Then, the cell transfer mechanism 4
1 checks the queue usage of the priority class 34 requested by the VC (step 303).

As a result, when the queue usage is less than a certain amount and the queue usage is low, the queue size of the queue 34 is not changed and the queue 34 is continuously registered in the queue 34 (step 30).
8). If the queue usage is higher than the certain amount and the queue usage is high, the queue usage of another priority class is monitored (step 304).

As a result of this monitoring, an unused queue specified by the management pointers 632 and 633 is allocated from the queue 33 in which the queue usage is low among other priority class queues and a certain amount of unused queue can be allocated. Change the queue sizes of the queues 33 and 34 (steps 305 and 305).
06).

To change the queue size, the management pointer designating the queue 33 is changed from the management pointers 631 and 632 to the management pointers 631 and 633, and the management pointer designating the queue 34 is changed from the management pointers 641 and 642 to the management pointers 641 and 643. (Step 307).

On the other hand, as a result of the monitoring, when the usage amount is low among other priority class queues and there is no queue to which a certain amount of unused queue can be allocated, the cells are temporarily stored in the buffer 8 in the cell transfer mechanism 41. (Steps 309 and 31)
0).

During this time, the processing of the queue 34 progresses to reduce the queue usage, or an unused queue of another priority class can be allocated, and the queue 34 is registered in the queue 34 by increasing the queue size. If possible, the cells stored in the buffer 8 are registered in the queue 34 (steps 311 and 308).

If the cells cannot be stored in the buffer 8 or if the cells cannot be transferred to the queue 34 within a predetermined time after being stored in the buffer 8, the cells are discarded (step 312).

The processing for changing the queue size as described above is performed in the other queues 31 and 32 as well.
Similarly to 34, the queue usage can be monitored and the queue management pointer can be changed to change the queue size. These queues 31 to 34 are transmitted from the line interface unit 55 (51 to 54) via the cell transfer mechanism 42 in accordance with the priority order.

Therefore, according to the ATM switching device 1 of the first embodiment, when the queues 31 to 34 are registered for the cells received by the line interface units 51 to 55, the VC
When the usage of the request priority class queue exceeds a certain amount, each priority class is used to temporarily allocate a certain amount of unused queue from other priority class queues as the request priority class queue of the VC. By changing the management pointer for each, the resources in the ATM switching device 1 can be effectively used, and the cell discard rate can be further reduced to guarantee the communication quality more efficiently.

(Embodiment 2) FIG. 4 is an explanatory diagram when a priority class is changed for each frame in an ATM switching apparatus according to a second embodiment of the present invention, and FIG. 5 is a diagram where the priority class is changed for each frame. It is a flowchart which shows a process.

The ATM switching device 1 according to the second embodiment is an ATM switching device having a plurality of queues for each priority class, similarly to the first embodiment, and includes queues 31 to 34 and a queue 31 for each priority class. , A cell switch unit 2 provided with a cell transfer mechanism 42 for transmitting cells, and line interface units 51 to 5.
5 is different from that of the first embodiment in that a process of changing the priority class is executed for each frame as a queue control method.

Here, an outline of a case where the priority class is changed for each frame will be described with reference to FIG.

FIG. 4 shows, by way of example, the priority class 3 having a low queue usage when the queue 34 usage is high at the time of receiving a cell of a VC having the priority class 34 as a request priority class.
When the priority class is changed to 3 and the queue is registered, the registration is continued in the queue 34 until the last cell 91 of the frame is received by the frame recognition function 7, and the queue 33 is transferred from the cell 92 constituting the next frame. Shows the structure to be registered.

Since the priority class is changed on a frame-by-frame basis, it is registered in the queue 34 until the next frame is received, or if the queue 34 does not have a considerable amount of unused queue corresponding to the frame being received. Are temporarily stored in the buffer 8 of the cell transfer mechanism 41, and are registered in the queue 34 after waiting for an empty state of the queue 34.

By changing the priority class to be used, the priority class can be changed while preventing the cell order from being reversed between the cell transferred by the original request priority class and the cell transferred by the high priority class. . Also, when the priority class is returned to the original request priority class, it is similarly performed in frame units.

Next, the ATM switching device 1 of the second embodiment
In the queue control method described above, a processing procedure when changing the priority class in frame units will be described with reference to FIG.

FIG. 5 shows a case in which, when the queue usage of the VC request priority class is high in accordance with the queue usage, the priority class is changed in frame units to a priority class having a high priority and a low queue usage, and the queue is changed. This realizes the registration process.

For example, from the request priority class 34 with a high queue usage to the high priority class queue 3 with a low queue usage
By changing the priority class to 3, the cell transfer of the VC is enabled.

In this queue control method, first, cells on the VC requesting the priority class 34 received by the line interface unit 51 (52 to 55) are sent to the cell transfer unit 41 (steps 501 and 502). Then, the cell transfer mechanism 4
1 checks the queue usage of the priority class 34 requested by the VC (step 503).

As a result, when the queue usage is less than the certain amount and the usage is low, the priority class is not changed and the queue is continuously registered in the queue 34 (step 508). If the queue usage is higher than the certain amount and the usage is high, the queue usage of another priority class is monitored (step 504).

As a result of this monitoring, if the queue 33 has a low usage and a high priority among other priority class queues, the priority class of the VC is changed from the queue 34 to the queue 33 (step 505).

In order to change the priority class, it is checked whether or not the received cell is in the middle of a frame.
If there is no vacancy, the buffer 8 temporarily stores the last cell of the frame until it is received (steps 506 to 508,
512).

In the meantime, if the queue 34 is processed and the queue usage is reduced and the queue 34 can be registered in the queue 34, it is registered in the queue 34; otherwise, the cell is discarded (step 5).
13, 511).

When the buffer 8 receives the first cell 92 of the next frame while accumulating the cells 91 as shown in FIG. 4, for example, it registers the cell 92 in the queue 33 (steps 509 and 510). If the cell 92 received at the time when the change to the queue 33 is determined is the head of the frame, the priority class is immediately changed and registration in the queue 33 is started.

On the other hand, as a result of monitoring, if there is no queue with low queue usage and high priority among other priority classes,
Discard the cell without changing the priority class (step 51)
1).

When the used amount of the priority class queue 33 is increased and the priority class is returned to the original priority class, the same operation is performed for each frame.

As described above, when the priority class is changed to a higher priority class with a smaller queue usage in accordance with the use status of the priority class, the priority class is changed on a frame basis, thereby preventing the order from being reversed on a cell basis. can do. The process of changing the priority class for each frame is as follows.
In the other queues 31 and 32, the queues 33 and 34 are also used.
Can be performed in the same manner.

Therefore, according to the ATM switching apparatus 1 of the second embodiment, when the queues 31 to 34 are registered for the cells 91 and 92 received by the line interface units 51 to 55, the request priority class queue If the usage exceeds a certain amount, change to a higher priority class with higher priority than the request priority class and lower queue usage, or change to the original request priority class according to the queue usage status By performing the processing in units of frames, it is possible to effectively utilize resources in the ATM switching apparatus 1, further reduce the cell discard rate, and more efficiently guarantee communication quality.

The present invention is not limited to the first and second embodiments, and it goes without saying that various changes can be made without departing from the scope of the present invention. For example, the queue control method may be any method that can dynamically assign and change unused priority control queues according to the usage status of each queue.
Cell transfer can be performed while effectively utilizing resources in the M switching device.

[0052]

According to the present invention, in an ATM switching apparatus having a plurality of queues for each priority class, when a cell is transferred, an unused queue is replaced with a queue having a higher queue usage according to the usage of the queue. Assigned as a class queue,
Alternatively, by changing the priority class instead of the priority class having a high queue usage and using the queue, the resources can be used efficiently and the cell loss rate can be reduced.

As a result, by dynamically changing the quota according to the use state of the queue, a large number of cells can be transferred without affecting the traffic. Quality can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an ATM switching device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram when a queue size is changed in the ATM switching device according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a process of changing a queue size in the ATM switching device according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram when a priority class is changed for each frame in the ATM switching device according to the second embodiment of the present invention;

FIG. 5 is a flowchart showing a process of changing a priority class for each frame in the ATM switching device according to the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... ATM switching device, 2 ... Cell switch part, 7 ... Frame recognition function, 8 ... Buffer, 31-34 ... Queue, 4
1, 42: Cell transfer mechanism, 51-55: Line interface unit, 91, 92: Cell, 631-633, 641-
643... Management pointer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norihiro Niwa 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Prefecture Hitachi, Ltd. Office Systems Division (72) Inventor Tomohisa Nishijima 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Hitachi, Ltd. (72) Inventor Nobuhito Matsuyama 1 Horiyamashita, Hadano City, Kanagawa Prefecture

Claims (1)

[Claims] 1. A plurality of priority control queues for controlling transfer of ATM cells corresponding to a plurality of priority classes, and a priority class required by each logical communication connection from a line interface unit for each logical communication connection. Means for registering each priority control queue to be executed, and means for processing the priority control queue for transmitting an ATM cell to the line interface unit from each of the priority control queues in accordance with priority. Monitoring the amount of use of the priority control queue corresponding to the priority control queue, and dynamically changing the allocation amount of the priority control queue corresponding to the priority class requested by the logical communication connection when transferring the ATM cell. Priority control queue control method in an ATM switching device.