Difference between revisions of "Ns-3-Network-Simulator/C2/Network-performance-Analysis/English"

Welcome

Learning Outcomes

• Use trace sources
• Create callback functions
• Connect trace sources to callback functions and
• Calculate network parameters using trace sources

System Requirements

• Ubuntu Linux Operating system version 22.04
• ns-3.38
• NetAnim visualizer tool

Prerequisite

https://spoken-tutorial.org

• You must have basic knowledge of using Linux terminal

• You must know how to create a point-to-point network in ns-3
• For pre-requisite Linux and ns-3 tutorials, please visit this website

Code files

• The files used in this tutorial are provided in the Code files link
• Please download and extract the files
• Make a copy and then use them while practising

Point-to-Point network with two nodes

• A point-to-point network with address 10.1.1.0

Now we will go through the source code in the text editor.

The source code contains the required functions to analyse network performance.

These variables shall hold the network parameters.

node0_trans_time holds the transmission time for node 0.

That is, the time taken to go from node 0 to node 1 and return.

It is set by us.

It is the rate of packet delivery.

It is executed whenever the client receives a packet.

The first argument is the traced source.

We shall explain trace sources later in this tutorial.

Here the traced source is Rx.

The second argument is the packet received.

Here, we set the value of the current time.

The current time is found using the GetSeconds method.

We set it to the sum of transmission and reception time of packets.

These values are represented by node0_trans_time and node0_rec_time.

The node0_trans_time variable would be updated in the TxTraceClient function.

We do so, to keep a track of the number of round-trips.

It is executed whenever the client sends a packet.

The first argument is the traced source.

The second argument is the receive packet.

The value is the time at which transmission starts.

It is executed when the server node receives a packet.

The first argument is the traced source.

The second argument is the received packet.

It is computed as the difference between two variables.

The first is the packet reception time of the server.

The second is the packet transmission time of the client.

The value is multiplied by 1000 to get the unit in milliseconds.

We get it by subtracting the value of propagation delay from total delay.

The propagation delay value is in nanoseconds, hence we divide it by 1000000.

This converts it into milliseconds.

We do this to know when the last packet is received.

If this is the last packet, we print all the parameters.

We print the parameters:

• End-to-end delay
• Transmission delay
• Throughput
• Propagation delay (constant)

For the topology, we create a point-to-point network with two nodes.

The index of the node is 1.

Both the times are from the start of the simulation.

The index of the node is 0.

These functions are also known as trace sinks.

A callback function is passed as an argument to another function.

These are used in conjunction with trace sources.

Trace sources are entities that signal events in an ns-3 program.

These events include packet transmission, change in window size etc.

The first is the Tx trace source, of the UdpEchoClient class.

It traces the transmission of a packet by an echo client application.

It traces the reception of a packet by an echo client application.

It traces the reception of a packet by an echo server application.

The parameter for the constructor is the name of the XML animation file.

It will be generated by the program after the simulation.

Here the name of the file is network_performance.xml.

Close the text editor.

Press Ctrl,Alt and T keys simultaneously.

Type cd ns-allinone-3.38/ns-3.38 to navigate to the ns3 installation directory

Type mv ~/Downloads/network_performance.cc scratch/network_performance.cc to move the source file to scratch directory.

Open a terminal by pressing Ctrl, Alt and T keys simultaneously.

Using the cd command, navigate to the installation directory of ns-3.

Go to the ns-3.38 directory.

Move your source file to the scratch directory within the ns-3.38 directory.

network underscore performance is the name of the source file.

• End-to-end delay
• Transmission delay
• Throughput and
• Round trip time

Navigate to the netanim directory under ns-allinone-3.38.

Select the network_performance.xml file.

The file would be generated by the program.

You can also download the file from Code Files section.

Select size 10.

We see the circles representing the nodes.

The lines with arrows represent the transfer of packets.

Summary

In this tutorial, we have learnt to

• Use trace sources
• Create callback functions
• Connect trace sources to callback functions
• Calculate network parameters using trace sources

Assignment

• Send packets from node 0 to node 2
• Calculate throughput and transmission delay

Assignment - Observation

The values may vary depending on the network parameters.

These parameters include packet size, propagation delay and data rate.

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Acknowledgement

Acknowledgement

We would also like to thank Dr. R. Radha, Dr. X. Anita, and Dr. T. Subbulakshmi from VIT, Chennai for their support.

Thank You

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