KR0123062B1 - Real time traffic generation method - Google Patents

Abstract

A real time traffic generating method where enables to build the variety test environment in order to test the ATM system and the observative function algorithm because of generating the real time cell, the single traffic and the multiplex traffic of theirs.

Description

Real time traffic generation method

1 is a schematic configuration diagram of a traffic generating apparatus to which the present invention is applied.

2 is a schematic overall flowchart of a traffic generating method according to the present invention;

3 is a block diagram of a lookup table of the next cell generation unit.

4 is a processing flowchart for calculating a next cell generation time.

5 is a structural diagram of a multiplexed memory.

6 is a flow chart of the emission processing of cells stored in the output list of the multiplexer.

7 is a flow chart of a next cell storage process of the multiplexer.

8 is a flowchart illustrating a process of moving from a multiplexer to an output list.

9 is a process flow diagram for initial cell generation.

The present invention relates to a method for generating real-time traffic in an asynchronous transfer mode (ATM) used in a broadband integrated telecommunication network (B-ISDN).

Conventionally, an ATM cell is generated in advance and stored in a storage device such as a memory, and then read or a simple traffic is generated in real time. However, among these methods, the former has the disadvantage that the generation pattern is repeated in a relatively short period due to the limitation of memory size and the high speed of 155.52Mb / s of ATM, and the existing generation method using the latter case occurs. Possible traffic types are extremely limited such as constant bit rate (CBR) or Poisson (Poisson), and there are problems such as not generating multiplexed traffic.

The present invention devised to solve the above problems, while generating a cell in real time, the constant bit rate (CBR), Poisson (Poisson), on-off (ON-OFF), intermittent Poisson probability process (IPP: Interrupted It can generate single traffic such as Poisson Process, Markov Modulated Poisson Process (MMPP), and also multiplexed traffic of them. The purpose is to provide a real-time traffic generation method that is easy to build a variety of test environment.

Here, the intermittent Poisson probability process (IPP) is a kind of random probability process, which has an exponentially distributed ON period and also an exponentially distributed OFF period. Traffic of course type arrives, and there is no cell arriving during the off period. In addition, the Markov Modulated Poisson Probability Process (MMPP) is also a random random process, which is often used to model B-ISDN traffic such as voice traffic or video traffic and traffic that overlaps such traffic.

In accordance with one aspect of the present invention, there is provided a real-time traffic generation method applied to a test apparatus of an asynchronous delivery mode system, the method comprising: generating and storing any number of initial cells for each virtual channel identifier; A second step of determining a type of cell to be released at any time and whether or not to release the cell with respect to the initial cell stored in the first step; A third step of inserting and discharging additional information necessary for the cell to be discharged determined in the second step; And releasing any other initial cell if the cell emitted in the third step is not the user cell, and calculating the next cell of the released cell if the emitted cell is the user cell. Characterized in that it comprises a fourth step of performing a process for storing.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a block diagram of a device consisting of a computer and a digital signal processing (DSP) board for generating real-time traffic to which the present invention is applied.

The computer downloads the program to the digital signal processing board and, upon receiving the processing result from the digital signal processing board, performs this overall control on the digital signal processing board. In addition, the denitrification signal processing board performs the operation of the present invention according to the program loaded from the computer.

2 shows a flowchart for schematically illustrating the present invention.

The present invention is largely divided into an initial cell generator and a processing routine. The initial cell generator generates the first k cells for each virtual channel (VC) in order to generate cells in real time, where the value of k is the type of traffic to be generated, the rate of occurrence, and the overall traffic load. And so on. After generating the initial cells, the main processing routine is performed.

The main processing routine is divided into three parts: the next cell generator, the multiplexer, and the cell information inserter. The multiplexer determines whether the cell is emitted in a certain time slot and the type of the cell to be emitted using the stored initial cells. The cell emitted from the multiplexer is transmitted to the outside after the necessary information is inserted by the information inserter. If the cell emitted is the user cell, the next cell of the cell emitted from the next cell generator is calculated to calculate the cell. Output to multiplexer. The multiplexer may generate multiplexed traffic by repeating the above process every time slot with initial cells and cells generated later.

3 is a block diagram of a lookup table, which is used to calculate a cell generation interval having an arbitrary distribution in the next cell generator.

When there is a random distribution X random distribution F (x), its lookup table is obtained as follows. Divide the Y-axis into equal 1024 sections, find the value for each section (A 구간), and store each value A 에 in the address from 1 to 1024 (1). Therefore, when a random number having a uniform distribution from 1 to 1024 is generated and the value of the lookup table is read with the address, a random number having a desired distribution can be generated. This configuration is for a single virtual channel (VC), and in order to extend it to multiple virtual channels, such a table should be allocated to each virtual channel (2). Accordingly, when selecting one of a plurality of tables, a virtual channel identifier (VCI) is used, and an address in the table uses a uniform random number, thereby calculating a random number having a desired distribution for each of the multiplexed virtual channels.

4 shows a flowchart for calculating the next cell generation time.

When the n-th cell of an arbitrary virtual channel identifier (VCI) i is emitted from the multiplexer (3), one random number X having a uniform distribution from 1 to 1024 is generated (4). After calculating the reference address LTad of the lookup table using the generated random number X and the VCI value (5), the reference address LTad of the lookup table is read (6) and the occurrence interval to the next cell is calculated. At this time, the next cell calculated is the n + k + 1th cell, and in order to calculate the occurrence time to the next cell, the previous cell that stores the time when the n + kth cell, which is the previous cell, is generated should be referred to. 7). The next cell generation time T is obtained by adding the generation time T _int of the current generated cell read from the lookup table and the generation time T _pre of the cells read from the past memory (8). The old memory is updated with the newly calculated cell generation time (9), and the n + k + 1th cell of the virtual channel VC i is input to the multiplexed memory (10). Here, the next cell becomes the n + k + 1th cell instead of the n + 1th cell to prevent the time reversal from occurring due to the standby phenomenon generated by the multiplexed traffic. Considering the case where k is 0 as an example, when the time for the nth cell to be emitted is 10 cell time and the current time is 10 cell time, the cell should be emitted at the current cell time in the multiplexer. However, assuming that the cell is actually released at 15 cell time due to the delay of cells previously scheduled to be released by generating multiplexed traffic, the present invention calculates the 15 cell time after the cell is released after calculating the next cell of that cell. Calculate the next cell of the cell released at 10 cell time at. In this case, when the calculated time of the next cell is 12 cell times, a case where the generated time is earlier than the current time occurs. Therefore, in order to prevent such time reversal, k value is required.

5 is a structural diagram of a multiplexed memory, in which a cell memory 11 is used as a part for storing actual cells, a part [storage part] scheduled to be released, and a free part [FL (free list) part where nothing is stored ], It is logically divided into the released storage part [OL (Output List) part] where cells to be discharged are stored. The basic storage unit is divided into a data area and a pointer area (12). The data area is a part for storing actual cell information, and the pointer area is an area for operating a cell memory in a linked list structure.

Three areas of cell memory are managed by six pointers, the storage of which is referred to by a calendar 13 consisting of a calendar head (CH) representing the beginning and a calendar tail (CT) representing the end. The free area FL is referred to by an FL head (FLH) representing the beginning of the free memory address and a free list tail (FLT) 14 representing the end of the free memory address. The storage portion OL to be ejected is provided by an output list head (OLH) representing the beginning of the memory address where the cell to be ejected is stored and an output list tail (OLT) 15 representing the end of the memory address where the cell to be ejected is stored. Reference is made. At this time, each column of the calendar represents time information, and moving one column to the right means elapse of one cell time.

The multiplexer performs three operations in order of releasing the cells stored in the storage portion OL to be largely released, storing the next cell, and moving the cell data to the storage portion OL in which the cell data is to be emitted.

6 shows a process flow diagram for the discharge of cells stored in the storage portion OL to be discharged of the multiplexer of the multiplexer.

First, it checks whether the OLH pointer value indicating the first address of the storage part to be released is 0 (16). If it is 0, there is no cell to be released. If not, the cell is stored in the memory corresponding to the address indicated by the OLH pointer. Read and release (17). Since one cell is discharged, an address having one free memory area is connected to the free area FL. That is, the value of the currently released OLH is stored in the pointer part of M (FLT) indicating the last part of the empty part of the memory (18), and the storage part of the cell currently emitted by the value of the FLT pointer indicating the last part of the empty part. Assign an OLH pointer value that represents (19). Then, the next OLH pointer value is calculated using the value of the pointer portion of the storage portion M (OLH) to be released, and the OLH pointer value is updated (20). Here, when the cell is released, the cell information is emitted by inserting the cell information, the virtual channel identifier (VCI), the sequence number (SN), and the time stamp (TS). Among the information inserted into the cell to be released, the virtual channel identifier (VCI) is included in the cell from the time of cell generation, and the sequence number SN is increased by one each time the cell stored for each virtual channel VC is released. The time stamp TS is normalized to cell time and incremented by 1 each time the main processing routine is repeated.

7 is a flowchart illustrating the process of storing the next cell of the multiplexer, and illustrates a process in which newly generated cells are stored in the memory of the multiplexer.

When the virtual channel identifier (VCI) and the generated time T are input as a result calculated in the next cell generation process, the pointer CH and CT values located at the time T to be emitted from the calendar are read (21 and 22). Pointer CH indicating the beginning of the storage part is checked whether the value of CH is 0 or not (23). If it is 0, since there is no previously stored cell, the pointer FLH value that stores the first address of the part where nothing is stored is converted into CH and CT pointer value. Store (24). Then, after storing the memory cell data of the address indicated by this FLH pointer (25), the value stored in the pointer portion of M (FLH) (i.e., the second value of the empty memory area) indicates the beginning of the empty portion. The next FLH pointer value is updated by assignment to the FLH (26).

If the CH pointer value is not 0, there is a previously stored cell, so after assigning the FLH to the pointer portion of M (CT) of the cell memory to connect the currently generated cell after the portion indicated by CT (27), Cell data is stored in M (FLH) (28), and FLH is substituted into CT (29). The next FLH is calculated to update the FLH (30).

8 is a flowchart illustrating a process of transferring cell data to an OL in the multiplexer.

First, it checks whether the CH pointer value is 0 (31). If it is 0, it means that there is no cell to be moved. 32). If the OLT pointer value is 0, there is no cell waiting to be released before, and CH is assigned to OLH. If OLT is not 0, CH is assigned to the pointer portion of M (OLT) (33). Then, after inserting CT into the OLT (34), CH and CT are cleared to 0 (35).

FIG. 9 is a flowchart for generating an initial cell, and shows an example in which an identifier VCI of a virtual channel VC to be generated is 1 to n.

First, the virtual channel identifier (VCI) is set to 1 (36), and then the number of cells K 'to be generated initially in the virtual channel having the virtual channel identifier (VCI) is read (37). This value is precomputed and stored in memory. Then, as shown in FIG. 4, the next cell generation time is calculated. That is, after generating a random number [X] having a uniform distribution between 1 and 1024, an address to be referred to is calculated using a virtual channel identifier (VCI) and a random number X. Then, after reading the time of the address to be referred to in the lookup table, reading the occurrence time of the previous cell stored in the past memory, the occurrence time of the next cell by adding the occurrence time of the current reference address and the occurrence time of the previous cell Calculate Then, a process of storing the next cell as described in FIG. 7 is performed. This process of calculating the next cell occurrence time and storing it is performed for all cells that should occur in the current virtual channel identifier (38,39), and then increasing the virtual channel identifier until n, that is, all virtual channels. Generate an initial cell for identification (40, 41).

The present invention made as described above, as well as the generation of a variety of single traffic, there is an effect that can generate their multiplexed traffic in real time.

Claims (5)

A real-time traffic generation method applied to a test apparatus of an asynchronous delivery mode system, comprising: a first step of generating and storing an arbitrary number of initial cells for each virtual channel identifier; A second step of determining a type of cell to be released at any time and whether or not to release the cell with respect to the initial cell stored in the first step; A third step of inserting and discharging additional information necessary for the cell to be discharged determined in the second step; And releasing any other initial cell if the cell emitted in the third step is not the user cell, and calculating the next cell of the released cell if the emitted cell is the user cell. Real-time traffic generation method characterized in that it comprises a fourth step of performing a process for storing. The method of claim 1, wherein the next cell calculation step of the fourth step comprises: generating a random number having a uniform distribution for the discharged cells; Calculating an address to be referred to in the lookup table using the virtual channel identifier of the cell and the random number; Reading an occurrence time of a cell stored in a lookup table corresponding to the address to be referred to, reading an occurrence time of a generated previous cell from a memory, and calculating the occurrence time of a next cell by adding the two read times; Updating the occurrence time of the previous cell of memory with the calculated occurrence time; And reading a next cell by referring to a pointer value indicating a cell storage portion corresponding to the calculated occurrence time. The method of claim 1, wherein the discharging of the cell comprises: reading a stored cell with reference to a pointer value indicating an address of a memory area in which the cell to be discharged is stored; Storing a pointer value of the read cell in a pointer representing an address of an empty memory area; Updating a pointer value of a cell to be released for release of the next cell; And inserting and emitting additional information into the read cell. The method of claim 1, wherein the storing of the next cell comprises: reading pointer values indicating first and last addresses of a storage memory area corresponding to a time to be emitted from a pointer area managing a memory area in which the cell is stored; Checking whether there is a stored cell by referring to a pointer value indicating the first address of the read stored memory area; If no cell is stored, a pointer value indicating the first address of the empty memory area is stored as a pointer value indicating the first and last address of the storage memory area, and the memory cell at the address corresponding to the pointer value indicating the first address of the empty memory area. Storing the; If there is a stored cell, the pointer value indicating the first address of the empty memory area is stored as a pointer value indicating the first address of the storage memory area, and the cell is stored in the memory of the address corresponding to the pointer value indicating the first address of the empty memory area. Updating a pointer value indicating a last address of the storage memory area; And calculating a next pointer value indicating the first address of the free memory area, and then updating the pointer value with the calculated value. The method of claim 1, wherein the initial cell generation comprises: reading and storing an arbitrary cell corresponding to an arbitrary virtual channel; Reading the cell and then calculating the occurrence time of the next cell; Reading and storing the calculated cell; And calculating and storing all cells and all virtual channels corresponding to the virtual channel through the steps.