Opnet Tutorial----M/M/1 Queue

Source: Internet
Author: User
Tags opnet

M/M/1 queue based on packet Poisson arrival process is first in, first out queues

The processor retrieves the package at a specific service rate

This section discusses the node editor and creates a M/M/1 queue

* Collect and statistic data

* How to use filters in the simulation process

* Analysis of data in simulations

Use the node and project editor to build a M/M/1 queue, collect statistics about the model, run and analyze the results.

The performance of the M/M/1 queue depends on:

Packet arrival rate

The size of the package

The ability of the server (processor)

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If the combined effect of packet arrival rate and packet size exceeds the processor's service capacity, the queue size will grow indefinitely

This article builds a M/M/1 queue model and ensures that the queue arrives at a specific arrival rate, the size of the package, and the stable state of the service capacity

M/M/1 Queue Model

Be aware of the issues to be addressed when establishing any network

Next, you will create

M/M/1 Queue System

The type of node module that simulates the system

Available for distribution of this model

The M/M/1 queue is typically described by a Poisson process (infinite buffer queue) that is processed by the server and sent to the destination when the packet reaches the head of the buffer

The queue model requires a way to build, queue, and service packages, all of which can be done in an existing node module that is available in the node editor.

To create a M/M/1 queue, you need to include a queue of two processors in the node editor.

The source module generates the package and the sink (receive) module is used to process the source-generated packets

Queues are infinitely large buffers and services

The source module (the processor module represents) generates a packet and specifies the build rate of the generated package based on the package/sec.

This speed is specified by grouping the curve exponential distribution (i.e., packet arrival time between queues).

A queue module can be used to represent an infinite buffer, or it can be used to represent a server. (The reason for using queues to represent servers is discussed later.) )

Although it is not part of the M/M/1 queue system described earlier, the sink module is used in the node model to process service packs. Destroys the data packets that are no longer needed, releasing the memory to be reused during the simulation.

The packet flow is used to connect each module in the node editor.

 

1. Creating the Processor

2. Create a queue

3. Create a package flow

4. Create a statistics line

5. Create logical send and accept associations

6. Create a point-to-point recipient

7. Create a point-to-point sender

8. Create a total Linetype recipient

9. Create a total Linetype sender

10. External System Module

Wireless receivers, senders and antennas

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Node Editor

Used to create a node model, consisting of modules connected by data flow and statistical lines.

The first step in creating a M/M/1 queue model is to define the source module for randomly generated packets, using the processor module to process

The modules in the node editor have properties that resemble the network objects in the Project editor. To specify the processor's build rate, build distribution, average packet size, and package size distribution, you must set these properties in the processor module.

Packet Interarrival Time property indicates the packet arrival interval

Packet the Size property indicates the package sizes and distributions

PDF refers to the probability density function, which is the distribution of random numbers, after setting the packet interval and the size of the package

The arrival is the exponential probability density distribution from 0 to infinity

The process model properties of the queue module set the underlying process model for the queue, which defines the behavior of the queue module.

The underlying process model that controls the behavior of the queue module Acb_fifo simulates the infinite buffers and servers in the m/m/1 queue.

Double-click the Queue module to view the process model

The name of the underlying process model ACB_FIFO reflects its main characteristics: "A" means that it is active (that is, it acts as its own server), "C" means it can centralize multiple incoming packet flows into its single internal queued resource, "B" indicates that the service time is a function of the number of bits in the packet, "FIFO" Represents a service collation.

Another consideration for assigning a process model to a node module is that the properties of the process model appear in the Properties list of the module. Therefore, the value of the Service_rate property that you set is also set in the underlying ACB_FIFO process model.

Now, all modules that simulate m/m/1 queues are placed in the workspace and configured correctly, and they must be connected through a packet so that the packets can be transferred between modules.

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Opnet Tutorial----M/M/1 Queue

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