KR100204493B1 - Traffic scheduler apparatus by 2x1 switch with static priority queueing discipline of atm networks - Google Patents

Abstract

The present invention is characterized in that a plurality of FIFO queues are selectively selected by a plurality of 2x1 switches corresponding to a plurality of FIFO queues and cells of the selected FIFO queue are processed, whereby the scalability of the FIFO queue The present invention relates to a traffic scheduler apparatus using a 2 × 1 switch in a fixed priority queue service scheme in an ATM network, and more particularly, to a traffic scheduler apparatus using a 2 × 1 switch, ; N FIFO queues 10 to n are connected to the first FIFO queue to the Nth FIFO queue 10 to n, respectively, by the amplifier FIF flag signal EF from the first FIFO queue to the Nth FIFO queue 10 to n, And first to n < th > x 1 switches (20 to n) for connecting the first to nth FIFO queues (10 to n) and the server (15).

Description

Traffic Scheduler Using 2 × 1 Switch in Fixed Priority Queue Service Scheme in ATM Networks

The present invention relates to a traffic scheduler apparatus using a 2 × 1 switch in a fixed priority queue service scheme in an ATM network. More particularly, a plurality of 2 × 1 switches corresponding to a plurality of FIFO queues enable a plurality of FIFO queues to be selectively And the cell of the selected FIFO queue is processed to improve the scalability of the FIFO queue by the same effect as the distributed control method. In the fixed priority queue service method in the ATM network, the traffic scheduler apparatus using the 2x1 switch .

Meanwhile, in the international telecommunication union-telecommunication standardization sector (ITU-TS), an asynchronous transfer mode (ATM) is adopted as an underlying technology in order to effectively construct a broadband integrated information communication network, The packet is formed into a packet having a limited size of information unit called a cell and is statistically multiplexed and transmitted so that the bandwidth can be efficiently used while flexibly accommodating services of different characteristics.

Therefore, the ATM network allocates the required bandwidth for calls that are allowed to connect, but unless the bandwidth of the peak bit rate is provided, the traffic of the connected call is already allocated It is possible to temporarily exceed the bandwidth.

This can cause the network to fall into congestion. Especially, traffic with high bursts, such as moving images and high-speed data, has a great impact on congestion. Therefore, various preventive and reactive level network control techniques are required to eliminate the disadvantages of the ATM network. One of them is priority control, By buffering the cells entering the network and changing the transmission priority according to the network status and the quality of service (QOS) of each class, the quality of service of all classes is fairly guaranteed, .

Meanwhile, a queuing service scheme is collectively referred to as a method of storing and managing arrival cells in a queue and a control method of determining a transmission order of stored cells. This is called a queue service scheme, Is a traffic control method for efficiently using resources of a base station. This means that the queue service method developed around the data communication network is not suitable for the ATM network.

First of all, there will be an unpredictable number of services in the ATM network, which will have significantly different traffic characteristics, both qualitatively and quantitatively. This means that the queue service method, which is significantly different from that of the data communication network with similar characteristics of data traffic It becomes an important factor to demand.

Since the ATM network service requires various service qualities, it must be handled differently depending on whether the service is sensitive to cell loss or delay-sensitive services. In the existing data communication network, the loss rate is a main service quality parameter. Real-time services such as voice and image services are included in the service quality related to the delay.

Therefore, in case of data service, the average delay time is a condition related to delay. In case of real-time service, if the condition for delay is very strict, if it can not be transmitted within the time limit, the same effect as lost is obtained. As such, the conditions for varying quality of service and strict delays become another factor requiring a new queue service approach.

In the queue service scheme, the service order is determined according to the delay requirement, so that each cell performs a service within the delay limit. The control method includes a FCFS scheme and a static priority scheme, Method and a dynamic priority method. Since the first-in first-out method is easiest to implement, but it can tolerate only one delay limit regardless of the type of traffic, the characteristics of the traffic are difficult to use in various networks. In the fixed priority method, It is possible to provide a delay limit for each class by performing the service with a fixed priority.

1 is a diagram illustrating an example of a general fixed priority queue service scheme. Here, the server prioritizes the packets of the FIFO queue having the higher priority, so that the order of the FIFO queue having the higher priority, for example, the first FIFO queue, the second FIFO queue, , And the Nth FIFO queue are sequentially scanned to process the packet. In such a case, since the fixed priority is always used irrespective of the state of the network, there is a problem that the efficiency is slightly lowered.

In the dynamic priority scheme, priority is given to each cell, and then service is provided from the highest priority. This method is most efficient, but all the cells must be classified to select the highest priority cell A problem occurs.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide an apparatus and method for managing a plurality of FIFO queues, The present invention provides a traffic scheduler apparatus using a 2 × 1 switch in a fixed priority queue service scheme in an ATM network in which the scalability of a FIFO queue is improved.

According to an aspect of the present invention, there is provided a data transmission system including: a first FIFO queue to an Nth FIFO queue in which traffic data is input and stored; A first FIFO queue to an Nth FIFO queue, respectively, and a first FIFO queue to an Nth FIFO queue, wherein the first FIFO queue to the Nth FIFO queue are connected to the first FIFO queue by an amplifier FIF flag signal from the first FIFO queue to an Nth FIFO queue, 1 to n < 2 > x 1 switches.

According to the present invention configured as described above, a plurality of FIFO queues are selectively selected by a plurality of 2 × 1 switches corresponding to a plurality of FIFO queues, and cells of the selected FIFO queue are processed, The scalability of the queue is excellent.

If the previous 2 × 1 switch is scheduled using the amplifier tee flag signal of each FIFO queue, regardless of whether or not the cell exists in another FIFO, the cell to be served in a fixed priority order can be selected, . ≪ / RTI >

FIG. 1 is a diagram illustrating an example of a general fixed priority queue service scheme;

FIG. 2 is a diagram showing the operation principle of a 2 × 1 switch,

FIG. 3 is a diagram illustrating an embodiment of a traffic scheduler using a 2 × 1 switch in a fixed priority queue service scheme in an ATM network according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

9: DEMUXs 10 to n: first to n-th FIFO queues,

13: control unit 15: server,

20 to n: first to n < th >

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the delay of the ATM cell can be divided into two components of a certain size of delay and irregular delay. In the former case, the delay caused by the cell disassembly and assembly process of the AAL layer is the main cause. The latter causes echo problems when interworking with the ATM network and the existing PSTN network. The latter causes latency that occurs during the multiplexing or switching process at the ATM layer and transmission of the operation, administration and maintenance (OAM) cells of the physical layer And the delay caused by the above.

Traffic with various quality of service and traffic characteristics is multiplexed and transmitted in an ATM network, and traffic with a variable bit rate allocated to a bandwidth below the maximum bit rate may exceed the negotiated bandwidth, which also causes congestion. Therefore, priority control performs cell loss distribution through selective cell storage, discard and transmission control, and ensures quality of service of a class sensitive to time delay through cell transmission order control.

In addition, the priority control is performed by controlling the priority according to the quality of service among the different traffic classes and the case where the priority bit of the cell head (head) in the same traffic such as MPEG video is low and high And controlling the storage and transmission of priority cells.

The queue service discipline means a method of storing and managing the arriving cells in the queue and a method of determining the transmission order of the stored cells, It is a traffic control method to maximize. The queue service method is required everywhere where there is a queue, such as a BISN (B-NT) network termination at the network entrance or an ATM switch over the entire network. In particular, traffic arriving at the B- Therefore, the queue service in B-NT has a very important effect on network efficiency and service quality.

In addition, the queue service method has been mainly developed based on existing data communication networks, and transmission delay variation is not a concern, and there has been an attempt to reduce the average transmission delay by first servicing packets having a short length. In addition, FCFS (first come first serve), which provides the first packet to arrive first, round robin (RR), which provides a fair buffer for each channel, and HOL (head of line) It can be said that it is a representative queue service method of existing data network.

However, in order to effectively accommodate various types of services in a BISDN environment that speeds up the integration of services, research on a completely different queue service method becomes necessary. Therefore, it is necessary to consider the cell delay variation (CDV) due to the integration of real-time service, guarantee different quality for each service, and maintain the quality of other services even when there is a connection generating excessive traffic .

On the other hand, the fixed priority scheme has a disadvantage in that the efficiency is considerably lower than that of the dynamic priority scheme. However, since the complexity of the implementation is considerably small, the queue service scheme is the most usable in reality. In the fixed priority scheme, After separation, each class is assigned a fixed priority.

Therefore, in order to select a cell to be serviced, the server searches for the cell having the highest priority level at each time point, and then the cell having the highest priority is selected and served. If there is no corresponding cell, the search is performed to determine whether there is a corresponding cell. If there is no cell corresponding to the next cell, the cell corresponding to the next cell is searched. In this manner, if a cell is searched sequentially from the highest priority, the corresponding cell is selected and processed.

FIG. 2 is a diagram showing the operation principle of a 2 × 1 switch, in which the amplifier FIFO signal EF of the FIFO queue, for example, (empty flag) signal is 0, it indicates that the contact from the server is in the contact state b, When the signal is 1, it indicates that the contact from the server is in the a contact state.

FIG. 3 is a diagram illustrating an embodiment of a traffic scheduler using a 2 × 1 switch in a fixed priority queue service scheme in an ATM network according to the present invention,

The same constituent elements as those in FIG. 1 are denoted by the same reference numerals, and a detailed description thereof will be omitted. In this case, the apparatus does not sequentially search for cell presence or absence in each grade, but has the same effect as searching by the dispersion control method at the same time. A system controller (not shown) controls the 2x1 switch by the amplifier FIFO signal EF of each FIFO so that a cell to be serviced is selected after a separate FIFO queue is used for each class, .

That is, when the system control unit schedules the immediately preceding 2 × 1 switch by the amplifier FIF flag signal from the predetermined FIFO, the cell to be serviced by the fixed priority is selected regardless of the existence of the cell from another FIFO, Lt; / RTI > to be serviced within the cell. Such a structure can be easily applied even when the number of classes is significantly increased.

It should be noted that the drawings are not intended to limit the technical scope of the present invention to the embodiments shown in the drawings in order to facilitate understanding of the present invention.

As described above, according to the present invention, a plurality of FIFO queues are selectively selected by a plurality of 2 × 1 switches corresponding to a plurality of FIFO queues, and cells of the selected FIFO queue are processed, The FIFO queue has excellent scalability.

If the previous 2 × 1 switch is scheduled using the amplifier tee flag signal of each FIFO queue, regardless of whether or not the cell exists in another FIFO, the cell to be served in a fixed priority order can be selected, . ≪ / RTI >

Claims (2)

A first FIFO queue to an Nth FIFO queue (10 to n) in which traffic data classified according to predetermined fixed priorities are inputted and stored; N FIFO queues 10 to n are connected to the first FIFO queue to the Nth FIFO queue 10 to n, respectively, by the amplifier FIF flag signal EF from the first FIFO queue to the Nth FIFO queue 10 to n, And a first to an n < th > 2 < 1 > switch (20 ~ n) for connecting the Nth FIFO queue (10 ~ Traffic Scheduler Using 2 × 1 Switch in Service Scheme. The method of claim 1, wherein the first to n < th > x 1 switches (20 to n) are connected to the first to n < th > FIFO queues When the signal is 0, it is in the b contact state, The traffic scheduler apparatus using the 2x1 switch in the fixed priority queue service scheme in the ATM network.