| 1 | [[PageOutline]] |
| 2 | |
| 3 | = TCP ASSIGNMENT = |
| 4 | |
| 5 | == Overview == |
| 6 | The objective of this exercise is to understand the impact of network conditions on the TCP congestion control algorithms. [[BR]] |
| 7 | You will learn about: [[BR]] |
| 8 | * The [http://www.hjp.at/doc/rfc/rfc2582.txt NewReno] loss recovery and intertwined congestion control mechanisms |
| 9 | * The [http://dl.acm.org/citation.cfm?id=1400105 CUBIC] congestion control mechanism |
| 10 | * The impact of the ''Slow Start Threshold (SSThresh)'' and ''congestion window size (CWND)'' TCP state variables on TCP network performance |
| 11 | * Measuring the performance of TCP flows |
| 12 | * The impact of path delay and bottleneck bandwidth on TCP performance |
| 13 | * TCP fairness concerns |
| 14 | * The Linux pluggable congestion control module interface. |
| 15 | |
| 16 | The following is the topology that you will be creating: [[BR]] |
| 17 | [[Image(GENIEducation/SampleAssignments/TcpAssignment/ExerciseLayout:TCPAssignment.png, 30%, nolink)]] |
| 18 | |
| 19 | |
| 20 | In this tutorial, we will show how to accomplish this assignment using either Omni or GENI Portal to: |
| 21 | - Reserve resources (exclusive physical PCs) from ProtoGENI |
| 22 | - Reserve resources (virtual machines) from InstaGENI |
| 23 | - Reserve resources (virtual machines) from ExoGENI |
| 24 | |
| 25 | This Project leverages resources on the GENI aggregate in order to experiment with TCP. [[BR]] |
| 26 | |
| 27 | |
| 28 | |
| 29 | == Prerequisites == |
| 30 | * GENI Account: |
| 31 | - Go to [https://www.pgeni.gpolab.bbn.com/reqaccount.php3 Request_GENI_Account] for an emulab account and to join a GENI project. |
| 32 | - Or get a GENI Portal account via: [https://portal.geni.net Portal Main Site] |
| 33 | * SSH |
| 34 | * Unix command line - see the Tools section |
| 35 | |
| 36 | == Tools == |
| 37 | The two primary tools used in this assignment are: [[BR]] |
| 38 | '''1. Traffic Control (tc)'''[[BR]] |
| 39 | The tc command is available in the GNU Linux distributions on GENI nodes, found in the ''/sbin'' directory. |
| 40 | This command manipulates the Linux network forwarding tables, allowing for configuration of queuing disciplines, |
| 41 | which change the policies controlling which packets are forwarded in what order and which are dropped; and network |
| 42 | emulation, which allows the Linux kernel to emulate various network conditions such as delay or loss. |
| 43 | These two effects are provided by the qdisc and netem subcommands, respectively. |
| 44 | In these exercises, tc will be used to modify network conditions and enable different scheduling policies. |
| 45 | Example command lines will be provided. |
| 46 | |
| 47 | '''2. [http://iperf.sourceforge.net/ Iperf]'''[[BR]] |
| 48 | Iperf is available on the GENI nodes, located at ''/usr/local/etc/emulab/emulab-iperf''. |
| 49 | Iperf is used to measure the bandwidth performance of Internet links. In these exercises, |
| 50 | it is used to study the behavior of TCP in the face of changing link characteristics. |
| 51 | Iperf runs as both a server and a client. The server is started with the -s command line option, |
| 52 | and listens for connections from the client. The client is started with the ''-c <server>'' command line option, |
| 53 | and connects to the server and sends data at either the fastest possible rate (given the underlying network) |
| 54 | or a user-specified rate. The -u option causes the sender or receiver to use UDP instead of TCP. |
| 55 | Various other options will be required for these exercises, and provided in the appropriate sections. |
| 56 | All Iperf measurement data should be recorded from the TCP receiver (server) side. |
| 57 | |
| 58 | == How to get Help == |
| 59 | * If you are using a specific aggregate or tool, you should consider registering in their [wiki:NikySandbox/GENIExperimenter/GENICommunity#Joinusermailinglists mailing list]. It is a great way to get connected with other GENI users and it is an excellent source of wisdom. |
| 60 | * Send mail to the GENI help list: [mailto:help@geni.net]. |
| 61 | * If you want to chat real-time with other GENI users and ask questions, [wiki:HowTo/ConnectToGENIChatRoom join us] in a GENI chatroom. |
| 62 | |
| 63 | == Resources == |
| 64 | * GENI resources include a variety of computational and network assets, all programmable by experimenters. Resources are made available to experimenters by GENI ''aggregates''. The [wiki:UnderstandingGENI UnderstandingGENI page] has more information in its [wiki:UnderstandingGENI#a2AnExperimentersViewofGENI "An Experimenter's View of GENI"] and [wiki:UnderstandingGENI#a3GENIResources "GENI Aggregates"] sections. |
| 65 | |
| 66 | == Tutorial Instructions == |
| 67 | {{{ |
| 68 | #!html |
| 69 | |
| 70 | |
| 71 | <table id="Table_01" height="409" border="0" cellpadding="0" cellspacing="0"> |
| 72 | <tr> |
| 73 | <td> |
| 74 | <a href="http://groups.geni.net/geni/wiki/GENIEducation/SampleAssignments/TcpAssignment/ExerciseLayout/DesignSetup"><img src="http://groups.geni.net/geni/attachment/wiki/GENIExperimenter/Tutorials/Graphics/design.png?format=raw" width="152" height="152" alt="Design/Setup"></a> |
| 75 | </td> |
| 76 | <td> |
| 77 | <ul> |
| 78 | <li><a href="http://groups.geni.net/geni/wiki/GENIEducation/SampleAssignments/TcpAssignment/ExerciseLayout/DesignSetup">Part I: Design/Setup</a></li> |
| 79 | <ul> |
| 80 | <li> Lists of steps for setting up the exercise </li> |
| 81 | </ul></ul> |
| 82 | </td> |
| 83 | </tr> |
| 84 | <tr> |
| 85 | <td> |
| 86 | <a href="http://groups.geni.net/geni/wiki/GENIEducation/SampleAssignments/TcpAssignment/ExerciseLayout/Execute"><img src="http://groups.geni.net/geni/attachment/wiki/GENIExperimenter/Tutorials/Graphics/execute.png?format=raw" width="152" height="143" alt="Execute"></a> |
| 87 | </td> |
| 88 | <td> |
| 89 | <ul> |
| 90 | <li><a href="http://groups.geni.net/geni/wiki/GENIEducation/SampleAssignments/TcpAssignment/ExerciseLayout/Execute">Part II: Execute</a></li> |
| 91 | <ul> |
| 92 | <li> Lists of steps for executing the exercise</li> |
| 93 | </ul></ul> |
| 94 | </td> |
| 95 | </tr> |
| 96 | <tr> |
| 97 | <td> |
| 98 | <a href="http://groups.geni.net/geni/wiki/GENIEducation/SampleAssignments/TcpAssignment/ExerciseLayout/Finish"><img src="http://groups.geni.net/geni/attachment/wiki/GENIExperimenter/Tutorials/Graphics/finish.png?format=raw" width="152" height="114" alt="Finish"></a> |
| 99 | </td> |
| 100 | |
| 101 | <td> |
| 102 | <ul> |
| 103 | <li><a href="http://groups.geni.net/geni/wiki/GENIEducation/SampleAssignments/TcpAssignment/ExerciseLayout/Finish">Part III: Finish</a></li> |
| 104 | <ul> |
| 105 | <li> Lists of steps for tearing down the exercise</li> |
| 106 | </ul></ul> |
| 107 | </td> |
| 108 | |
| 109 | </tr> |
| 110 | </table> |
| 111 | |
| 112 | }}} |