Trabalho de Redes - Point To Point Wifi

ECE 6110 Lab Assignment 1 Topologies Before starting the assignment you should download the latest version of ns3 at the time of this lab creation ns3361 from httpswwwnsnamorg and go through the ns3 tutorial Chapters 47 Chapter 4 takes you stepbystep through the process of downloading and installing ns3 Chapters 57 provide the concepts you will need to complete this assignment Note for Windows users Windows users should install VirtualBox and Linux prior to downloading ns3 Notes on Random Numbers in ns3 Random number generation is very important in simulations and in particular the ability to exactly reproduce the same random scenario multiple times is often required This is handled automatically by ns3 but requires the programmer to use the builtin ns3 random number generation methods Information about using ns3 random number generation can be found in the Doxygen documentation on the ns3 Web site under ModulesCoreRandom Variables Please use these builtin ns3 methods instead of other random number generators such as rand from the C standard library Note that there is no need to set a seed for the ns3 random number generator Turnin Instructions Create a separate folder for each part of the assignment inside a main folder named Lab1yourlastnameyourfirstname Then create a single tarball of the main folder and all of its subfolders and submit it in Canvas Important programming instructions All code must be hand typed in your editor of choice No auto formatting is allowed to change the text that you type in manually Also make sure to use the exact program name and commandline parameter names specified in each part You will get points deducted if you do not follow these instructions even if your code is functionally correct Alternate application for extra credit This lab has been designed to closely follow the ns3 tutorial which uses the UdpEchoServer and UdpEchoClient applications to send packets and get replies back This can also be done using ping which uses the ICMP protocol that is part of the IP protocol stack For extra credit implement the entire lab using ping instead of UdpEchoServer and UdpEchoClient For help using ping in ns3 see V4Ping in the ns3 Doxygen documentation and look at the example program in NSDIRsrccsmaexamplescsmapingcc where NSDIR is the directory in which you installed ns3 Part 1 Working with PointtoPoint Links In this part you will modify the example firstcc described in Chapter 5 of the tutorial You will set up multiple client nodes each one with a pointtopoint link to the server The number of clients and the number of packets sent by each client should be settable through commandline parameters up to a maximum of 5 clients and 5 packets per client In the absence of a commandline argument your program should assign a default value of 1 to those parameters Name your program lab1part1cc and name the command line parameters nClients and nPackets An example of the network topology with 3 clients is shown below where n0 is the server and n1 n2 and n3 are the clients 10120 10110 n2 n0 n1 pointtopoint pointtopoint p 2 10130 p n3 Important notes 1 The clients requests should all be sent to the same IP address which following the setup in firstcc is 10112 Since the clients after n1 are on different subnets this will require the use of a concept introduced later in the ns3 tutorial in the secondcc example to make sure that the requests from all clients reach the server 2 How to set up and use commandline parameters are also introduced in the secondcc example 3 Set the start times for the UdpEchoClient apps on the clients to be different random times between 2 and 7 seconds Set the stop time for the UdpEchoClient apps the UdpEchoServer app and the simulation to 20 seconds 4 Use the SetAttribute method to change the port number for the UdpEchoServer app to 15 5 All other parameters should have the same values as in firstcc ie the data rate and delay of each pointtopoint link and the interval and packet size for each UdpEchoClient Turnin instructions In your Part 1 subfolder include the source code of your program a screen shot showing the command line and the output when there are 5 clients and 4 packets per client and a text file containing the output for the same case Part 2 Working with an Ethernet Network In this part you will modify the example secondcc described in Section 71 of the tutorial You will add a second pointtopoint link from the last node on the CSMA network to another node which will contain the UdpEchoServer The number of packets sent by the UdpEchoClient should be settable through a commandline parameter up to a maximum of 20 packets In the absence of a commandline argument your program should assign a default value of 1 to the number of packets sent Set the parameters of the second pointtopoint link delay and data rate to be the same as the first pointtopoint link Name your program lab1part2cc and name the commandline parameters nCsma and nPackets An example of the network topology with 4 CSMA nodes 3 extra nodes is shown below where n0 is the client and n5 is the server 10110 10130 n0 n1 n2 n3 n4 n5 pointtopoint pointtopoint LAN 10120 Important note Make sure to extend the stop times of the client and server to be long enough for the maximum simulation run of 20 packets Modify the original secondcc to send up to 20 packets in a similar manner Now for a run of 10 packets and 5 CSMA nodes 4 extra nodes plot the endtoend delay of a requestresponse pair vs the packet number for your modified topology and the original topology 10 data points for each topology Answer the following questions related to the delays You will need to do some analysis of the PCAP files to answer these questions Collect the same PCAP files as in the original secondcc program and any additional ones you need to help you answer these questions 1 If your program is running correctly you should notice that the endtoend delay for the first requestresponse is significantly longer than the subsequent ones For this question focus on the delays after the first one Since the pointtopoint link delays are 2 ms and the CSMA delays are in microseconds you might expect the endtoend requestresponse delay to be around 4 ms for the original topology and around 8 ms for the modified topology Is this what you see If not explain the discrepancy focusing solely on the characteristics of the pointtopoint links and ignoring other delays Provide a calculation that gives a better rough estimate of endtoend delays for the two topologies 2 Now consider the delay of the first requestresponse sequence Looking carefully through the relevant PCAP files state where this additional delay occurs and explain why it happens Turnin instructions In your Part 2 subfolder include the source code of your program with the modified topology and the following for your 10packet runs a screen shot showing the command line and the output for your modified topology a text file containing the output for the same case all PCAP files that you captured for the same case at a minimum the 3 PCAPs captured by the original secondcc program the endtoend delay vs packet number plots for the original topology and your modified topology and the answers to the two questions above Part 3 Working with WiFi Networks In this part you will modify the example thirdcc described in Section 73 of the tutorial You will replace the Ethernet LAN in the example with a second WiFi network having the same number of nodes as the first WiFi network You should create a second physical channel for the second WiFi network The STA nodes for the second network should move within the same region as the nodes in the first network This models a scenario where there are 2 APs in an area operating on different nonoverlapping wireless channels nodes in the area can associate to either of the APs and communications on the two networks can coexist without interference because they operate on different frequency bands As in Part 2 modify your program to have the number of packets as a commandline parameter up to a maximum of 20 packets and make sure all end times in your simulation are long enough to accommodate that many packets An example of the modified topology with 3 WiFi STA nodes per network is shown below where n7 is the client and n4 is the server Name your program lab1part3cc and name the command line parameters nWifi and nPackets Note that nWifi should be no greater than 9 here instead of 18 as it was in thirdcc since the total number of WiFi nodes is 2nWifi Wifi 10130 AP 10110 n7 n6 n5 n0 n1 n2 n3 n4 pointtopoint AP Wifi 10120 As in Part 2 plot the endtoend requestresponse delay vs packet number for your modified topology for a run with 10 packets and 4 WiFI STA nodes per network What is different about the endtoend delays for packets 2 through 10 as compared to the results from Part 2 What do you think explains this difference Hint Why do you think there is no parameter to set the data rate on the WiFi channels the way there was for both pointtopoint and CSMA channels Turnin instructions In your Part 3 subfolder include the source code of your program with the modified topology a screen shot showing the command line and the output for the 10 packet and 4 STA nodes per network case a text file containing the output for the same case the endtoend delay vs packet number plot and the answers to the two questions above