View source for Ns-3-Network-Simulator/C2/CSMA-based-network-with-bus-topology/English


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|| '''Visual Cue'''
|| '''Narration'''
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|| '''Slide:1'''
|| Welcome to Spoken tutorial on '''CSMA based network with bus topology'''.
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'''Learning Objectives'''
|| In this tutorial, we will learn to
* Create a '''CSMA''' based '''bus topology''' with '''10 nodes'''
* Configure client and server applications on the nodes
* Connect the two nodes and routing packets from one node to the other
* Visualize the network using '''NetAnim'''

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|| Show Slide: 

'''System Requirements'''
|| To record this tutorial, I am using
* '''Ubuntu Linux OS''' version '''22.04'''
* '''ns-3 '''version 3.38.
* '''NetAnim''' visualizer tool.

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'''Pre-requisites'''
|| To follow this tutorial:
* The learner must have basic knowledge of using Linux terminal
* The learner must have understanding of network topologies
* For pre-requisite Linux and ns-3 tutorials, please visit this website [https://spoken-tutorial.org/ https://spoken-tutorial.org]

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'''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 practicing.
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'''Bus topology'''
|| For this tutorial, we would be creating the following topology.

A bus network topology with '''10 nodes''' and network address '''10.1.1.0.'''
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|| Open '''csma_performance.cc''' source file
|| I have created the source file '''csma_performance.cc''' for this program.

The source code contains the required functions to implement a '''CSMA''' based''' bus topology'''.

Here, I have routed the packets from the '''first node''' to the '''tenth node'''.

Now we will go through the source code for the program. 
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|| Highlight '''uint32_t nCsma = 10'''
|| We set the number of nodes in the '''CSMA '''network to 10.
|-
|| Highlight '''double trans_time_1'''
|| This represents the transmission time ''' at the client'''.
|-
|| Highlight '''double rec_time_1'''
|| This defines the receiving time at the server
|-
|| Highlight the line '''static void'''

'''TxTraceClient'''

|| This is the function created to '''trace''' the '''client application'''.
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|| Highlight '''if (context[10] == '0')'''
|| We use '''context '''to find which node has transmitted the packet.
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|| Highlight '''trans_time_1 = Simulator::Now().GetSeconds();'''
|| We shall define the '''transmission time''' by getting the current time in seconds from the simulator.
|-
|| Highlight '''static void'''

'''RxTraceServer'''
|| This is the function created to '''trace''' the '''server application.'''
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|| Highlight '''if (context[10] == '9')'''
|| Here, '''context''' is used to get the''' node ID '''whenever the server gets the packets.
|-
|| Highlight '''rec_time_1'''
|| We then define the receiving time by getting the current time in seconds from the simulator.
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|| Highlight '''delay_1 '''and '''(rec_time_1 - trans_time_1)*1000'''.
|| Next, we use '''delay_1 '''to find the '''delay''' using this formula. 
|-
|| Highlight '''if (pkt_cnt_1 == pkts)'''
|| If we have reached the last packet, we have to print the '''parameters'''.
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|| Highlight '''NodeContainer csmaNodes'''
|| Then, we create a '''node container''' for the CSMA network.
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|| Highlight '''csmaNodes.Create(ncsma)'''
|| Let us create a number of '''CSMA''' nodes assigned earlier using the '''Create() '''method.
|-
|| Highlight 

'''CsmaHelper csma'''
|| The '''CsmaHelper''' is a helper class for initializing the '''CSMA''' network.

This is the helper class to access the '''CSMA channel''' created.
|-
|| Highlight '''csma.SetChannelAttribute'''
|| Using the '''setChannelAttribute '''method, let us set the attributes for the CSMA network.
* '''Data rate''' 100 Mbps.
* Channel '''delay''' 6560 nanoseconds or 0.00656 milliseconds.

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|| Highlight '''stack.Install(csmaNodes)'''
|| This command installs an internet stack on the nodes of the '''CSMA ''' bus network.
|-
|| Highlight '''address.SetBase '''and '''address.Assign(csmaDevices)'''
|| The highlighted command assigns''' IP addresses''' to the nodes of the network. 

Now we set the '''base address'''  10.1.1.0 for the '''bus network '''.
|-
|| Highlight '''UdpEchoServerHelper echoServerA(9);'''

|| The '''UdpEchoServerHelper''' class is used to install server applications on a node of the network. 

An''' echo server '''receives the packet from the client.

The received packet is echoed back.
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|| Highlight '''echoServer.Install(csmaNodes.Get(9))'''
|| The tenth node of the''' CSMA network''' has '''index 9'''.

Let us '''install''' an '''echo server application '''on the tenth node.
|-
|| Highlight '''serverApps.Start(Seconds(1.0))'''
|| Set the '''start''' of the server application to '''1 second'''. 
|-
|| Highlight '''serverApps.Stop(Seconds(10.0))'''
|| The '''stop time''' is '''10 seconds''' after the start of the '''simulation'''.
|-
|| Highlight '''UdpEchoClientHelper echoClientA(csmaInterfaces.GetAddress(9), 9);'''
|| The '''UdpEchoClientHelper''' class is used to install client applications on a node of the network. 

An '''Echo client '''enables the node to send and receive echo packets from the server.
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|| Highlight '''echoClient(csmaInterfaces.GetAddress(9), 9);'''
|| Let us '''install''' an '''echo client application'''.

The target server is''' node 10''' of the CSMA network.

The '''port '''is set to''' 9'''. 
|-
|| Highlight '''echoClientA.SetAttribute'''
|| This command is used to set the attributes of the client.
|-
|| Highlight '''PopulateRoutingTables()'''
|| Now, for the packets to be routed across the bus network, routing must be enabled.

To enable '''routing''' across the bus network, we use this method.
|-
|| Highlight '''AnimationInterface anim ("csma-performance-analysis.xml")'''
|| Let us specify the name for the '''XML output file'''.
|-
|| Highlight the lines:

'''anim.SetConstantPosition() '''
|| Set the position of the nodes using the '''SetConstantPosition() '''method.
|-
|| Highlight '''Simulator::Run()'''
|| The '''Run()''' function is used to run the simulation.
|-
|| Highlight '''Simulator::Destroy()'''
|| '''Destroy() '''function ends the simulation.

Now close the text editor.
|-
|| Press '''Ctrl, Alt '''and '''T keys''' simultaneously

Navigate to the '''ns-allinone-3.38/ns3.38 '''directory


Type '''mv ~/Downloads/csma_performance.cc scratch/csma_performance.cc '''to move the source file to '''scratch '''directory.
|| Now we will observe the simulation.

Open the 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'''.
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|| Type ./'''ns3 run scratch/csma_performance.cc'''
|| Now, run the command '''./ns3 run scratch/csma_performance.cc '''

'''csma_performance.cc '''is the name of the source file. 
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|| Keep the terminal open and show the output of the command 
|| After compilation, we get the details of each '''packet transfer'''.

We see the '''average end to end delay and throughput '''of the '''CSMA''' network.
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|| Navigate to '''netanim '''directory under '''ns-allinone-3.38'''

Type '''cd ..'''

Type '''cd netanim'''
|| Now, to visualize the network, we will use '''NetAnim'''. 

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

For that, type '''cd space .. '''in the terminal window.

Then type '''cd space netanim'''
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|| Type ./'''NetAnim'''
|| Now type '''./NetAnim. '''

The '''NetAnim''' window should open.
|-
|| Click on the Open''' XML trace file '''icon on the top left corner of the window.
|| Click on the''' Open XML trace file '''icon on the top left corner of the window.
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|| In the file picker, navigate to the '''ns-allinone-3.38/ns3.38 '''directory and select the '''csma-performance-analysis.xml '''file.
|| In the file picker, navigate to the '''ns-allinone-3.38 '''and then to the '''ns3.38 '''directory.

Then select the '''csma-performance-analysis.xml '''file.
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|| On the toolbar, click on the '''play''' button

Close the NetAnim window
|| On the toolbar, click on the''' play button''' to view the simulation.

Now we can observe the packet transfer.

Now, we can close the''' NetAnim''' window.
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|| Show Slide: '''Summary'''
|| This brings us to the end of this tutorial.

Let us summarize. 

In this tutorial, we have 

* Created a '''CSMA''' '''bus topology''' with '''10''' nodes
* Configured '''client '''and '''server applications '''on the '''nodes'''
* Connected the''' two''' nodes and '''routing packets''' from one '''node '''to the other
* Visualized the network using '''NetAnim'''

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|| Show Slide :''' Assignment'''
|| As an assignment, please do the following

* Create 10 nodes
* Connect each of them using '''p2p helper''' classes
* Initialize''' CSMA '''network using '''csmaHelper()''' class
* Set''' datarate '''and '''delay'''
* Route the packets from the second node to the eighth node
* Visualize the network using '''NetAnim'''

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|| Show Slide :''' Assignment - Observation'''
|| In the terminal, you will get the following output.

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|| Show Slide :''' Assignment - Observation '''
|| In the '''NetAnim''' window, you would observe the packet transfer from node-2 to node-8.

Observe the packet transfer.
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'''About Spoken Tutorial Project'''
|| The video at the following link summarizes the '''Spoken Tutorial project'''.

Please download and watch it.
|- 
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'''Spoken Tutorial Workshops'''
|| The '''Spoken Tutorial Project''' team conducts workshops and gives certificates.

For more details, please write to us.
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'''Answers for THIS Spoken Tutorial'''
|| Please post your timed queries in this forum.
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'''FOSSEE Forum'''
|| For any general or technical questions on '''ns-3''', visit the''' FOSSEE forum''' and post your question.
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|| Show Slide: '''Acknowledgement'''
|| '''Spoken Tutorial''' Project was established by the '''Ministry of Education, Government of India'''.

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|| Show Slide: '''Acknowledgement'''
|| We thank '''Dr.Moyukh Laha''' from '''IIT Kharagpur''' for his domain support.

We would also like to thank '''Dr. R. Radha, Dr. X. Anita, and Dr. T. Subbulakshmi '''from''' VIT, Chennai '''for their support.

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|| Show Slide: '''Thank you'''
|| This is '''Arun Santhosh''', a FOSSEE Summer Fellow 2023, IIT Bombay signing off.

Thank you for joining.
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