KR100191257B1 - Apparatus for real-time queue service discipline using virtual clock algorithm in atm networks - Google Patents

Abstract

Each deadline generator constituted by two counters is connected to each virtual channel, and based on the amplifier T flag signal EF from the independent FIFO queue and the virtual channel information sel_VC selected from the deadline comparator, (RT) for a head of line (HOL) cell of the asynchronous transfer mode communication network, the deadline comparator outputs a connection identifier (CID) for selecting a cell to be served based on the deadline The present invention relates to a real-time cue service apparatus using a virtual time algorithm using virtual time algorithms, in which data is input from a plurality of virtual channels (VC1 to VCn) and first to nth FIFO queues (10-n); (HOL) on the basis of the amplifier flag flag signals EF1 to EFn from the first to nth FIFO queues 10 to n and the virtual channel information sel_VC selected by the deadline comparing means 40 First to n < th > dead time generating means (30 to n) for outputting dead time (RT1 to RTn) Compares the deadlines (RT1 to RTn) from the first to nth deadline generating means (30 to n) and compares deadline times for outputting virtual channel information (sel_VC) for connection of virtual channels having a minimum deadline Means (40); A multiplexer 20 for connecting the predetermined FIFO queues to be served among the first to the n-th FIFO queues 10 to n by using the virtual channel information sel_VC from the deadline comparing means 40, .

Description

A real-time queue service apparatus using a virtual time algorithm in an asynchronous transfer mode communication network.

The present invention relates to an implementation of a real-time queue service method using a virtual time algorithm in an asynchronous transfer mode communication network. More particularly, each deadline generator composed of two counters is connected to each virtual channel, If the deadline time (RT) for each head of line (HOL) cell of each queue is output based on the signal EF and the virtual channel information sel_VC selected from the deadline time comparator, To a real time cue service apparatus using a virtual time algorithm in an asynchronous transfer mode communication network in which a connection identifier (CID) for selecting a cell to output is output.

In the international telecommunication union-telecommunication standardization sector (ITU-TS), an asynchronous transfer mode (ATM) is adopted as an underlying technology to effectively promote a broadband integrated information communication network, cell), and statistically multiplexing and transmitting the packet. Therefore, 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, .

Conventionally, the priority control scheme is mainly based on a FIFO (first in first out) queue common buffer. When this buffer is used, only buffer occupancy control is possible.

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

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

In addition, the priority control is performed in the case of controlling the priority according to the quality of service between different traffic classes and the case in which the priority bit of the cell head (head) And the case of controlling the storage and transmission of high 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 .

Meanwhile, the conventional method of implementing the virtual clock queue service method is complicated because it is necessary to arrange all the cells in the queue based on the deadline, and it is impossible to operate at high speed.

In order to solve the above-mentioned problems, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a virtual channel If the deadline time (RT) for the head of line (HOL) cell of each queue is output based on the information sel_VC, the deadline comparator calculates a connection identifier (CID) for selecting a cell to be served based on the deadline And to provide a real time cue service apparatus using a virtual time algorithm in an asynchronous transfer mode communication network.

According to an aspect of the present invention, there is provided a data transmission system including first to n-th FIFO queues for receiving data from a plurality of virtual channels and outputting an amplifier te flags signal; First to n-th deadline generation means for outputting a deadline based on the amplifier tee flag signal from the first to n-th FIFO queues and the virtual channel information from the deadline time comparator; Comparison means for comparing the deadlines from the first to n-th deadline time generating means and outputting the minimum time sequentially; And a multiplexer for selectively outputting a connection type discriminator from the first to the n-th FIFO queues according to virtual channel information from the comparison means.

According to the present invention configured as described above, each deadline generator constituted by two counters is connected to each virtual channel, and based on the amplifier chip flag signal from the independent FIFO queue and the virtual channel information selected from the deadline comparator, The deadline time comparator outputs a connection identifier for selecting a cell to be served based on the deadline time. Therefore, a single deadline generator manages all the cells existing in each queue, which facilitates management and simplifies the configuration.

1 is a block diagram showing an embodiment of a real-time cue service apparatus using a virtual time algorithm in an asynchronous transfer mode communication network according to the present invention;

2 is a block diagram of the deadline generator shown in FIG.

Description of the Related Art [0002]

10 to n: first to n-th FIFO queues, 20: multiplexer,

22, 23: first and second counters, 24: deadline output unit,

25: OR gate, 26: multiplier,

27: adder,

30 to n: first to nth deadline generators, 40: deadline comparator.

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

1 is a block diagram illustrating an embodiment of a real-time queue service apparatus using a virtual time algorithm in an asynchronous transfer mode communication network according to the present invention, wherein the real-time queue service apparatus includes first to n-th FIFO queues 10- A first to an n-th finishing time generator 30 to n, and a deadline time comparator 40. The first to n-th finishing time generators 30 to n-

First, data arriving from each virtual channel (VC) is stored in a separate queue for each connection, for example, in the FIFO queues 10 to n, The stored data is selectively serviced by the multiplexer 20 and output. Here, when the cell arrives, the data is input to the corresponding queue, and the multiplexer 20 outputs a connection identifier (CID) for selecting a cell to be served.

When data is input from the virtual channel to the FIFO queues 10 to n, the deadline generator 31 to n outputs an empty-flag EF from the FIFO queue 10 to n, Dead time information (RT) remaining time to the deadline is output based on the selected virtual channel information sel_VC from the dead time comparator 40 and the dead time information EF1 to EFn and the deadline comparator 40, .

The deadline comparator 40 compares the deadlines RT1 to RTn from the deadline generator 31 to the virtual channel information sel_VC for selecting a cell to be served from the multiplexer 20, And the deadline generator 31 to n. Thereafter, the multiplexer 20 selects cells from the FIFO queues 10 to n according to the virtual channel information sel_VC from the deadline time comparator 40, so that the multiplexer 20 can receive services.

FIG. 2 is a block diagram of the deadline generator shown in FIG. 1, wherein the deadline generator includes first and second counters 22 and 23, a deadline output 24, an OR gate 25, 26, an adder 27, and a comparator 28. As shown in FIG.

The first counter 22, for example, a down counter may be preset (PR) by a high level signal, for example, a value of 1, of the amplifier T flag EF before the cell arrives, , Such as 11 ... 1. The second counter 23, for example, a down / up counter, is reset by a high level signal of the amplifier T flag EF, for example, a value of 1, for example, 00 ... 0 < / RTI > At this time, the deadline output unit 24 outputs the maximum time, for example, 11 ... 1 and the dead time RT becomes logically infinite (∞).

The first counter 22 is preset by the flow set value Vtick when it is decremented by one every hour, that is, every one cell service time, and becomes 0, and the second counter 23 is preset by the head- A cell in the head of line (HOL) is incremented by 1 after receiving a service and decremented by 1 when the first counter 22 becomes 0.

Here, the dead time of the cell in the head of line (HOL) and the next cell is different by the flow set value (Vtick). Accordingly, when the queue becomes an amplifier, the first counter 22 is preset and the second counter 23 is reset to prepare a cell to be input later, at which time the deadline is pre-set and logically infinite So that it is not selected by the deadline time comparator 40.

On the other hand, when the flow set value Vtick is set to a predetermined value, for example, 5, when the cell arrives for the first time, since the value of the previous amplifier flag EF is 1, 1 counter 22 so that the first counter 22 is preset to 5. Then, the second counter 23 is reset (reset), for example, becomes 0, and the value of 0 is input to the multiplier 26, so that the output value of the multiplier 26 becomes zero. Accordingly, the deadline outputting unit 24 receives only the flow set value Vtick, for example, 5 from the first counter 22, and outputs the deadline RT, that is, a value of 5.

Next, the expression indicating the deadline time of the virtual channel (VC)

[Equation 1]

VC _i = max (VC _i-1 + V _tick , AT _i + V _tick )

. In Equation (1), i denotes an i-th cell and AT _i denotes an arrival time of an i-th cell.

On the other hand, if the flow set value Vtick is 5, if the virtual clock for the arriving cell is expressed as follows,

Here, if the first cell is input at t = 3 seconds, the virtual time of the first cell is

VC1 = max (0 + 5, 3 + 5) = 8 seconds

When the second cell is input at t = 4 seconds, the virtual time of the second cell is

VC2 = max (8 + 5, 4 + 5) = 13 seconds

Further, when the third cell is input at t = 11 seconds, the virtual time of the third cell is

VC3 = max (13 + 5, 11 + 5) = 18 seconds

When the fourth cell is input at t = 19 seconds, the virtual time of the fourth cell is

VC4 = max (18 + 5, 19 + 5) = 24 seconds

Further, when the fifth cell is input at t = 20 seconds, the virtual time of the fifth cell is

VC5 = max (24 + 5, 20 + 5) = 29 seconds.

The comparator 28 compares the value of the high level signal, for example, 1, with the value of the virtual channel information sel_VC selected from the deadline comparator 40, for example, when the predetermined address information matches the address information of the predetermined virtual channel VC . At the same time, the service for the cell of the virtual channel (VC) at the corresponding address is performed. Thereafter, the value of 1 from the comparator 28 causes the second counter 23 to increment by one.

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, each deadline generator composed of two counters is connected to each virtual channel, and based on the amplifier chip flag signal from the independent FIFO queue and the virtual channel information selected from the deadline comparator, When the deadline (RT) for the head of line cell of the queue is output, the deadline comparator outputs a connection identifier for selecting a cell to be served based on the deadline. Therefore, a single deadline generator manages all the cells existing in each queue, which facilitates management and simplifies the configuration.

Claims (6)

First to n-th FIFO queues (10 to n) for receiving data from a plurality of virtual channels (VC1 to VCn) and outputting an amplifier teflag signal (EF); (HOL) on the basis of the amplifier flag flag signals EF1 to EFn from the first to nth FIFO queues 10 to n and the virtual channel information sel_VC selected by the deadline comparing means 40 First to n < th > dead time generating means (30 to n) for outputting dead time (RT1 to RTn) Compares the deadlines (RT1 to RTn) from the first to nth deadline generating means (30 to n) and compares deadline times for outputting virtual channel information (sel_VC) for connection of virtual channels having a minimum deadline Means (40); A multiplexer 20 for connecting the predetermined FIFO queues to be served among the first to the n-th FIFO queues 10 to n by using the virtual channel information sel_VC from the deadline comparing means 40, Wherein the real time cue service apparatus uses the virtual time algorithm in the asynchronous transfer mode communication network. 2. The apparatus according to claim 1, wherein the dead time generating means (30 to n) are preset (PR) by amplifier flag signals (EF1 to EFn) from the FIFO queues (10 to n) A first counter (22) decreasing by 1; Comparing means (28) for comparing the selected virtual channel information (sel_VC) and the virtual channel information (VC) from the deadline comparing means (40) and outputting a high level signal when they match; Is reset by the amplifier flag signals EF1 to EFn from the FIFO queues 10 to n and is decremented by 1 when the first counter 22 becomes 0, A second counter 23 which is incremented by one by a high level signal from the first counter 28; A multiplication means (26) for multiplying an output value from the second counter (23) by a flow set value (Vtick); An adding means (27) for adding an output value from the multiplying means (26) and an output value from the first counter (22); (PR) from the FIFO queues (10 to n) and the added value from the adder (27) are input to output the deadlines (RT1 to RTn) And a deadline outputting means (24) for outputting a deadline for outputting the deadline of the asynchronous transfer mode communication network. 3. The method of claim 2, wherein the first counter (22) counts a preset (PR), e.g., 11 ... 1, and is preset by the flow set value (Vtick) after it is decreased by a predetermined set value every hour interval, that is, one cell service time, and becomes 0, and real time using the virtual time algorithm in the asynchronous transfer mode communication network Queue service device. 3. The method of claim 2, wherein the second counter (23) is reset (R) by a high level signal of the amplifier T flag (EF) before the cell arrives, The count is increased by the high level signal from the comparator (28), and the count is decreased by the low level signal from the first counter (22) in the asynchronous transfer mode communication network A Real - Time Queue Service Device Using Virtual Time Algorithm. The apparatus according to claim 2, wherein the deadline outputting unit (24) outputs the maximum time by a high level signal of the amplifier T flag (EF) before the cell arrives, 1 < / RTI > using a virtual time algorithm in an asynchronous transfer mode communication network. 3. The method as claimed in claim 2, wherein the comparison means (28) compares the value of 1 when the virtual channel information sel_VC selected from the deadline time comparator (40), for example, the predetermined address information and the address information of the predetermined virtual channel And outputting the virtual time algorithm using the virtual time algorithm in the asynchronous transfer mode communication network.