KR100221323B1 - Method of controlling the cell delay by using the time interval between previous cells at the upc of uni in atm networks - Google Patents

Abstract

The present invention provides user parameter control (UPC: User Parameter Control) for monitoring the traffic volume of a connection link at a user network interface (UNI) and a network node interface (NNI) in an asynchronous transmission mode communication method. A first step (S1) of detecting an arrival time t of cell data input from the user terminal; A second step S2 of comparing the cell data in the first step S1 with the previous cell interval information PreT and the flow setting value T based on the previous cell data; As a result of the comparison in the second step S2, when the previous cell interval information PreT is smaller than the flow setting value T, the flow arrival value of the previous cell is added to the arrival time of the previous cell to add the theoretical arrival time of the current cell. A third step S3 of defining a TAT; As a result of the comparison in the second step S2, when the previous cell interval information PreT is not smaller than the flow set value T, the average value of the previous cell interval and the current cell interval is not smaller than the flow set value T. A fourth step S4 of defining a theoretical arrival time TAT of the current cell; After defining the theoretical arrival time (TAT) of the current cell in the third step (S3) and the fourth step (S4) and updating the previous cell interval information (PreT) and arrival time (LAT) information for the next cell It is characterized by consisting of five steps (S5).

Description

Cell spacing method using previous cell spacing information in user variable control (UPC) at user network interface (UNI) of asynchronous transmission mode communication network

The present invention relates to a cell spacing method using previous cell spacing information in user variable control (UPC) at a user network interface (UNI) of an asynchronous transmission mode communication network. In the User Parameter Control (UPC), which monitors the traffic volume of the access link at the User Network Interface (NNI) and Network Node Interface (NNI), the arrival time (LAT: Last Arrival Time) of the previous cell is determined. User's network of asynchronous transmission mode communication network that increases cell bandwidth and reduces complexity of output port for high-capacity ATM switch by transmitting cell by optimal calculated theoretical arrival time (TAT) The present invention relates to a cell spacing control method using previous cell spacing information in user variable control (UPC) at the interface.

Meanwhile, in the international telecommunication union-telecommunication standardization sector (ITU-TS), an asynchronous transfer mode (ATM) is adopted as an underlying technology to effectively construct a broadband integrated information communication network. Since information is transformed into packets of limited sized information units called cells, which are transmitted by statistical multiplexing, bandwidth can be efficiently used while accommodating various services.

Thus, asynchronous transmission mode networks allocate the necessary bandwidth for a call that is allowed to access, but unless the bandwidth of the peak bit rate is provided, the traffic of the connected call is already allocated due to unpredictable characteristics. The bandwidth can be temporarily exceeded. As a result, the network may be congested. In particular, bursty traffic such as moving images or high-speed data may have a large impact on the congestion.

The delay of the ATM cell can be divided into two components, a constant size delay and an irregular delay. In the former case, the delay caused by the cell decomposition and assembly of the AAL layer is a main cause. When the transport mode network and the existing PSTN network are interworked, it causes echo problems. The latter causes delays in the multiplexing and switching processes in the ATM layer, and the operation, administration and maintenance (OAM) of the physical layer. The delay is caused by transmission.

In addition, traffic having various quality of service and traffic characteristics is multiplexed and transmitted in an asynchronous transmission mode communication network, and traffic having a variable bit rate allocated to a bandwidth below the maximum bit rate may exceed the negotiated bandwidth, which may cause congestion. do. Therefore, priority control is performed to guarantee quality of service of a class that is sensitive to time delay through cell loss distribution and cell transmission order control through selective cell storage, discarding, and transmission amount control.

FIG. 1A illustrates the arrival time of a virtual channel (VC) cell input from a user in a user variable control (UPC) at a user network interface (UNI) of a general asynchronous transmission mode communication network. FIG. 1B is shown in FIG. 1A. Is a diagram showing the departure time of a cell adjusted by a general cell spacing control method. Here, the virtual time for the cell of the virtual channel (VC) is shown in Equation 1 below.

It becomes Here, in Equation 1, i represents the i-th cell, AT _i represents the arrival time (arrival time) of the i-th cell.

On the other hand, if the flow set value (T) is "6" to indicate the departure time for the arrival cell as follows:

Here, when the first cell is input at t = 3 seconds, the departure time of the first cell is

VC1 = max (0, 3) = 3 seconds

And, if the second cell is input at t = 4 seconds, the departure time of the second cell is

VC2 = max (3 + 6, 4) = 9 seconds

Also, when the third cell is input at t = 11 seconds, the departure time of the third cell is

VC3 = max (9 + 6, 11) = 15 seconds

And, if the fourth cell is input at t = 29 seconds, the departure time of the fourth cell is

VC4 = max (15 + 6, 29) = 29 seconds

In addition, when the fifth cell is input at t = 30 seconds, the departure time of the fifth cell is

VC5 = max (29 + 6, 30) = 35 seconds.

As such, since the cell spacing is constantly maintained based on the flow set value T, the implementation of the cell data is considerably complicated, and the cell data is transmitted by reducing the bandwidth for the cell data when a congestion of cell data occurs from the user. There was a delayed issue.

Accordingly, the present invention is to solve the above problems, the user monitoring the traffic volume of the access link in the user network interface (UNI) and network node interface (NNI: Network Node Interface) of the asynchronous transmission mode communication network In the User Parameter Control (UPC), the cell is transmitted by the optimal theoretical arrival time (TAT) calculated based on the last arrival time (LAT) of the previous cell. A method for adjusting cell spacing using previous cell spacing information in user variable control (UPC) at user network interface (UNI) of asynchronous transmission mode communication network to increase bandwidth and reduce output port complexity for large capacity ATM switch will be.

The present invention for achieving the above object, in the user variable control (UPC) for monitoring the traffic volume of the connection link at the user network interface (UNI) and network node interface (NNI) of the asynchronous transmission mode communication network, Detecting a arrival time t of cell data input from the user terminal; A second step of comparing gap information and a flow setting value of the previous cell based on the cell data in the first step and the previous cell data; A third step of defining the theoretical arrival time of the current cell by adding the flow setting value to the arrival time of the previous cell when the comparison result of the second step is smaller than the flow setting value; A fourth step of defining a theoretical arrival time of the current cell such that the cell gap between the previous cell and the current cell is smaller than the average cell gap when the interval information of the previous cell is not smaller than the flow setting value as a result of the comparison in the second step; And; After defining the theoretical arrival time of the current cell in the third step and the fourth step, and the fifth step of defining the interval information and the arrival time of the previous cell for the next cell.

The present invention configured as described above, the arrival time of the previous cell in the user variable control (UPC) for monitoring the traffic volume of the connection link at the user network interface (UNI) and network node interface (NNI) of the asynchronous transmission mode communication network Cells are transmitted by the optimal theoretical arrival time (TAT) calculated on the basis of the LAT, thereby increasing the bandwidth for cell transmission and reducing the complexity of the output port for a large capacity ATM switch.

FIG. 1A illustrates the arrival time of a virtual channel (VC) cell input from a user in user variable control (UPC) at a user network interface (UNI) of a general asynchronous transmission mode communication network.

FIG. 1B is a diagram illustrating a departure time of a cell in which a cell shown in FIG. 1A is adjusted by a general cell spacing method;

2 is a diagram illustrating a connection state through user variable control (UPC) at a user network interface (UNI) of a general asynchronous transmission mode communication network;

3 is a flowchart illustrating an embodiment of a method for adjusting cell spacing using previous cell spacing information in user variable control (UPC) at a user network interface (UNI) of an asynchronous transmission mode communication network according to the present invention;

FIG. 4A illustrates a virtual channel (VC) cell input from a user in a cell spacing control method using previous cell spacing information in a user variable control (UPC) at a user network interface (UNI) of an asynchronous transmission mode communication network according to the present invention. Shows the arrival time of,

4B is a diagram illustrating a departure time of a cell in which a cell shown in FIG. 4A is adjusted by a cell gap adjusting method using previous cell gap information.

* Explanation of symbols for the main parts of the drawings

i-1 to i + n: node, A to F: subscriber.

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

In general, the advantages of an asynchronous transmission mode network are increased efficiency and flexibility to support various services at the same time, but the problems of traffic control and resource management must be solved to fully realize these advantages. To this end, the asynchronous transmission mode communication network provides traffic control capabilities such as connection acceptance control (CAC), user variable control (UPC), network variable control (NPC), priority control (PC), and congestion control (CC).

Although the traffic control problem has been studied a lot in the existing packet communication network, in this case, the demanding service quality or geographically extensive service area required for high-speed connectivity and connectionless real-time service in BISDN is not usually considered. Moreover, the data rate in BISDN is high, but the propagation speed in the optical fiber is constant.

Therefore, the existing packet network is bandwidth bounded, but BISDN is basically bounded by delay. For example, in BISDN, window-based flow control, which is widely used in conventional packet communication, is considered to be difficult to exhibit a large effect due to a high data rate and relatively long propagation delay.

Afterwards, the more fundamental problem is that in BISDN, measures against congestion should be checked in terms of preventing congestion before dealing with congestion.

On the other hand, there are three main goals in traffic control and resource management. The first goal is to protect the network, that is, prevent the abuse of the right to use many resources temporarily. The second goal is to maintain the performance of the network, that is, to maintain the performance indexes such as cell propagation delay or cell loss rate provided by the network within a certain range, and the third goal is to efficiently use network resources, i.e. satisfy the required quality of service. Use only the minimum resources needed to do this.

Then, to understand the basic structure of traffic control in BISDN, the procedure of call setup is as follows. This highlights the sequence of events in the network at call control side.

First, a connection is requested by passing traffic parameters representing the statistical characteristics of a signal source requiring call establishment to the network. Subsequently, the connection acceptance control (CAC) unit within the network accepts the connection by determining whether the new call can be connected while guaranteeing the quality of service of the preset call based on the current state of the network and the characteristics of the signal source requiring the call establishment. When a new call is established, the source and the network operator enter into a call establishment agreement that defines the traffic characteristics of the connection.

On the other hand, the network operator sets up a route to forward the user's call to the destination, avoiding the place where the jam occurred. When the call is set, the signal source sends a cell to the network (call) and the network operator presents the statistical data presented by the signal source. User variable control (UPC) is performed to monitor whether or not a call setup contract based on a characteristic is being observed.

In the above process, the network may allocate network resources according to service characteristics (resource management), or may control the traffic flow sent by the user to the network by using feedback control. The user can also send cells with different priorities using the CLP bit.

2 is a diagram illustrating a connection state through user variable control (UPC) at a user network interface (UNI) of a general asynchronous transmission mode communication network. Here, it can be seen that CAC occurs in all networks, UPC is performed at the beginning of the network in UNI, and network variable control (NPC) is performed at the beginning of the network coming from NNI between networks as variable control of network node interface. .

On the other hand, user variable control and network variable control are for the network to monitor and take measures of user traffic in terms of traffic volume and cell path validity, and its main purpose is that network resources are damaged by malicious or unintentional faults. To prevent it. In other words, it monitors whether the user's traffic variables are out of the negotiations during call setup and takes corresponding measures.

The connection monitoring is applied to all connections passing through the UNI or NNI, and the UPC / NPC is applied to the user VCC / VPC and the virtual channel for the signal. The monitoring contents of the UPC / NPC include checking the validity of the VPI / VCI value, monitoring the traffic volume for the VP and VC, and monitoring the total traffic volume of the access link.

Therefore, the user variable control algorithm should have the ability to detect illegal traffic conditions, discriminate whether the identified variable exceeds the limit, and facilitate the quick response to the violation of the variable use. It may be all or part of the traffic characteristic variables used for connection admission control.

On the other hand, when observing the synchronous transmission network in terms of traffic, the information required for call setup is only the maximum transmission rate required by the call. Therefore, the call setup is simple but wastes bandwidth, and the asynchronous transmission mode transmission method adopts the concept of statistical multiplexing to maximize bandwidth efficiency. Since the statistical multiplexing supports a service with a bandwidth smaller than the sum of the maximum bandwidths of several signal sources, it is important to be aware of the characteristics of the signal sources. In other words, the statistical characteristics of the signal source should be grasped and used to control the traffic of the network.

The one side of the statistical traffic characteristics of the signal source is referred to as a traffic variable, and the various ones of the various traffic variables to represent the traffic characteristics of the ATM connection are called a traffic descriptor. That is, the traffic descriptor of a signal source is a set of traffic variables that represent the traffic characteristics of the contract when a connection contract is made between the signal source and the network.

Examples of the traffic variable may include an average bit rate, a maximum bit rate, a variance of bits, a burst length, and the like. In this case, the traffic descriptor is a set made by taking these traffic variables as elements to describe the statistical characteristics of the signal source. For example, a set of {average bit rate, maximum bit rate, variance of bit rate, average cluster length} can describe the overall characteristics of a signal source.

The traffic variable must satisfy various conditions that can be used to control the traffic of the network. First, the traffic variable must be a variable that can be declared by the user. In addition, traffic variables should be able to be monitored and controlled by user variable control (UPC) or network variable control (NPC).

Then, when several signal sources are multiplexed, since the respective statistical characteristics are diluted to some extent, it is desirable to define a traffic variable representing the statistical characteristics of the signal source as close to the signal source as possible. Therefore, the traffic variable is preferably defined at any part of the ATM layer before ATM-SAP or multiplexing.

On the other hand, when congestion occurs anywhere, the quality of service provided by the network is deteriorated, and the main goal of traffic control is to prevent such congestion and to eliminate it when congestion occurs. Therefore, there are two major measures to minimize the damage caused by congestion in the communication network. The first method is to cope with the moment when congestion occurs or is about to occur. This method is commonly referred to as reactive control. The method is to take precautionary measures to prevent congestion. This method is called preventive control.

In addition, in the conventional packet communication network, the correspondence control is widely used, but in the BISDN, since the propagation delay is high and the transmission rate is high, the correspondence control is difficult to exhibit a large effect. Therefore, in the asynchronous transmission mode communication network, preventive control has emerged as the main means of traffic control rather than corresponding control.

In addition, another criterion for dividing the traffic control method is a different classification to the level to which the traffic control is applied. That is, traffic control can be divided into control of cell level and control of cell level. The control method of cell level includes user variable monitoring (UPC / NPC) or buffer management. Control methods include connection admission control and VC routing. On the other hand, the control of the virtual path level may consider a virtual path allocation for each service or a simplified connection admission control.

3 is a flowchart illustrating an embodiment of a method for adjusting cell spacing using previous cell spacing information in user variable control (UPC) at a user network interface (UNI) of an asynchronous transmission mode communication network according to the present invention.

On the other hand, in User Parameter Control (UPC), which monitors the traffic volume of a connection link at a user network interface (UNI) and a network node interface (NNI) of an asynchronous transmission mode communication network. The cell spacing adjustment method using previous cell spacing information is as follows.

First, in the first step S1, the arrival time t of the cell data input from the user terminal is detected. In the second step S2, the cell data and the previous cell data in the first step S1 are detected. The interval information PreT of the previous cell is compared with the flow set value T.

In the third step S3, when the interval information PreT of the previous cell is smaller than the flow setting value T as a result of the comparison in the second step S2, the flow setting value ( T) is added to define a theoretical arrival time (TAT) of the current cell, and in the fourth step S4, as a result of the comparison in the second step S2, the interval information PreT of the previous cell is the flow set value T. If not smaller than), the theoretical arrival time (TAT) of the current cell is defined such that the cell gap between the previous cell and the current cell is smaller than the average cell gap.

In the fifth step S5, the theoretical arrival time TAT of the current cell is defined in the third step S3 and the fourth step S4, and then the interval information PreT of the previous cell and the next cell are defined. You will define the arrival time (LAT).

On the other hand, the method of defining the theoretical arrival time (TAT) of the current cell of the third step (S3) is as follows. First, in step 3-1 (S3-1), when the interval information PreT of the previous cell is smaller than the flow setting value T, as a result of the comparison in the second step S2, the arrival time of the previous cell LAT ) And the flow set value T are determined whether the arrival time t is greater than the arrival time t.

In addition, in step 3-2 (S3-2), a value obtained by adding the arrival time LAT and the flow setting value T of the previous cell is determined as the result of the determination in step 3-1 (S3-1). If the arrival time is greater than t, the flow set value T is added to the arrival time LAT of the previous cell to define the theoretical arrival time TAT of the current cell.

In addition, in step 3-3 (S3-3), as a result of the determination in step 3-1 (S3-1), a value obtained by adding the arrival time LAT and the flow setting value T of the previous cell is added. If it is not larger than the arrival time t, the theoretical arrival time TAT of the current cell is defined as the arrival time t.

Meanwhile, a method of defining the theoretical arrival time TAT of the current cell of the fourth step S4 is as follows. First, in step 4-1, if the interval information PreT of the previous cell is not smaller than the flow set value T, the constant k is determined as a result of the comparison in the second step S2. In step 4-2 (S4-2), the step 4-1 (S4-1) is performed. Set to It is determined whether is greater than the arrival time t.

In addition, in step 4-3 (S4-3), as a result of the determination in step 4-2 (S4-2), Is greater than arrival time t, the theoretical arrival time (TAT) of the current cell is LAT + In step 4-4 (S4-4), as a result of the determination in step 4-2 (S4-2), Is not greater than the arrival time t, the theoretical arrival time TAT of the current cell is set to the arrival time t.

In addition, the interval information PreT of the previous cell in the fifth step S5 is defined by a value excluding the arrival time LAT of the previous cell from the theoretical arrival time TAT of the current cell. The arrival time (LAT) of the previous cell is defined by the theoretical arrival time (TAT) of the current cell.

On the other hand, whether to accept a cell entering an asynchronous transmission mode network depends on the traffic parameters negotiated between the network and the user during the call setup period.The UPC should monitor the compliance of the negotiation parameters while the connection is established. The UPC algorithm of sanctioned sanctions such as discarding a cell that has been negotiated or sending a mark to the CLP bit, but passes the network without changing the characteristic of other cells.

It is pointed out that such a highly crowded cell can enter the network and make network traffic control very difficult, which is caused by cell delay variation in the subscriber-network or is deliberately negotiated by the user. This can occur by sending dense cells within a range not broken.

In order to prevent such a phenomenon, it is necessary to control the cell spacing according to the negotiated parameters, as well as the operation of discarding the cell that the UPC has negotiated. The above operation can be performed by adding a special type of traffic shaper known as a cell spacing controller to the existing UPC, and the amount of additional hardware required is about 10% of the UPC. The cell spacing control means that any cell is properly delayed such that the spacing between adjacent cells leaving the UPC is more than the minimum spacing allowed by the negotiated maximum cell rate.

On the other hand, if one virtual channel is configured for the monitored link, the cell interval can be controlled by using a server that transmits at a negotiated cell rate with one FIFO queue. For example, if 10% of the link capacity is allocated at the maximum cell rate, transmission can be performed once every 10 cell cycles, but in general, one link is shared by a large number of virtual channels. At the same time, the cell spacing control is very complicated.

In other words, all virtual channels are demultiplexed, and then the multiplexing is performed after monitoring and cell spacing control is performed separately. From the implementation point of view, it is impractical to use a separate queue for each virtual channel.

Therefore, the existing researches include a Spacer-Controller (SC) algorithm, which is based on the Virtual Scheduling Algorithm (VSA), which is currently considered as a candidate for UPC in ITU-T. It's one of the ways.

For example, the method calculates the theoretical arrival time (TAT: Theoretical Arrival Time) of the next cell by adding the cell interval to the arrival time of the previous cell, where sanctions are imposed if the next cell arrives significantly earlier than the TAT. In this way, some hardware may be added to configure the cell spacing controller.

Subsequently, in the present embodiment, not only the arrival time information (LAT: Last Arrival Time) of the previous cell but also the cell interval information (PreT: Previous T) between the previous cells are used together. The theoretical arrival time (TAT) of the current cell is defined so that the cell gap between the cell and the current cell is smaller than the average cell gap.

Here, the average cell spacing should not be greater than the bandwidth (1 / T) allocated to the connection. To this end, in this embodiment, After calculating k using the relation of, the theoretical arrival time of the current cell is replaced with the arrival time of the previous cell. It is defined as the sum of. In this case, it is easy to see that the average interval between successive cells is not smaller than T.

In addition, when the distance between the previous cells is not significantly larger than T, the theoretical arrival time (TAT: Theoretical Arrival Time) of the current cell is defined as in the conventional method. In other words, T is added to the arrival time of the previous cell, and then the theoretical arrival time (TAT) of the next cell is calculated.

FIG. 4A illustrates a virtual channel (VC) cell input from a user in a cell spacing control method using previous cell spacing information in a user variable control (UPC) at a user network interface (UNI) of an asynchronous transmission mode communication network according to the present invention. 4B is a diagram illustrating a departure time of a cell in which a cell shown in FIG. 4A is adjusted by a cell spacing method using previous cell spacing information.

Here, as shown, even if the cell-to-cell spacing, e.g., the flow set value T is set to "5", the previous cell spacing is so large that the current cell spacing is made small. The cell spacing is, on average, larger than the flow set value (T) because Therefore, the inter-cell spacing is determined by fully utilizing the allocated bandwidth without exceeding the allocated bandwidth.

Explained above

Claims (4)

In User Parameter Control (UPC), which monitors the traffic volume of a connection link at a user network interface (UNI) and a network node interface (NNI) of an asynchronous transmission mode communication network, Detecting a arrival time t of cell data input from the user terminal (S1); A second step S2 of comparing the cell data in the first step S1 with the flow setting value T and the interval information PreT of the previous cell based on the previous cell data; As a result of the comparison in the second step S2, when the interval information PreT of the previous cell is smaller than the flow setting value T, the theoretical arrival of the current cell is added by adding the flow setting value T to the arrival time of the previous cell. A third step S3 of defining a time TAT; As a result of the comparison in the second step S2, when the interval information PreT of the previous cell is not smaller than the flow setting value T, the cell gap between the previous cell and the current cell is smaller than the average cell gap. A fourth step S4 of defining a theoretical arrival time TAT; After defining the theoretical arrival time (TAT) of the current cell in the third step (S3) and the fourth step (S4) and the interval information (PreT) and arrival time (LAT) of the previous cell for the next cell 5. A method of adjusting cell spacing using previous cell spacing information in a user variable control (UPC) at a user network interface (UNI) of an asynchronous transmission mode communication network, comprising five steps (S5). The method of claim 1, wherein the third step S3 is based on the arrival time of the previous cell when the interval information PreT of the previous cell is smaller than the flow setting value T as a result of the comparison in the second step S2. Step 3-1 (S3-1) for determining whether the value obtained by adding the LAT) and the flow set value T is greater than the arrival time t; As a result of the determination in step 3-1 (S3-1), when the sum of the arrival time LAT and the flow setting value T of the previous cell is greater than the arrival time t, the arrival time of the previous cell ( Step 3-2 (S3-2) of defining a theoretical arrival time (TAT) of the current cell by adding the flow set value T to LAT; If the value obtained by adding the arrival time LAT and the flow setting value T of the previous cell is not greater than the arrival time t as a result of the determination in step 3-1 (S3-1), the theoretical arrival of the current cell In the user variable control (UPC) at the user network interface (UNI) of the asynchronous transmission mode communication network, characterized in that the time (TAT) is composed of the third step (S3-3) defining the arrival time t. Cell spacing method using cell spacing information. The method of claim 1, wherein the fourth step S4 is a constant k when the interval information PreT of the previous cell is not smaller than the flow set value T as a result of the comparison in the second step S2. Step 4-1 (S4-1) to set to; In this 4-1 step (S4-1) Set to Step 4-2 (S4-2) to determine whether is greater than the arrival time t; As a result of the determination in step 4-2 (S4-2) Is greater than arrival time t, the theoretical arrival time (TAT) of the current cell is LAT + Step 4-3 of setting S4-3; As a result of the determination in step 4-2 (S4-2) Is not greater than the arrival time t, the user network interface of the asynchronous transmission mode communication network, characterized in that it comprises a fourth step (S4-4) of setting the theoretical arrival time (TAT) of the current cell to the arrival time t ( Cell spacing method using previous cell spacing information in User Variable Control (UPC) in UNI). The method of claim 1, wherein the interval information PreT of the previous cell in the fifth step S5 is defined by a value excluding the arrival time LAT of the previous cell from the theoretical arrival time TAT of the current cell. The arrival time (LAT) of the previous cell is defined by the theoretical arrival time (TAT) of the current cell. User variable control (UPC) at the user network interface (UNI) of the asynchronous transmission mode communication network. A cell spacing method using previous cell spacing information in a.