Your Wireshark window should look similar to the window shown below. Once the file has been uploaded, a short congratulations message will be displayed in your browser window. Returning to your browser, press the “ Upload alice.txt file ” button to upload the file to the gaia.cs. server. Now start up Wireshark and begin packet capture (Capture->Start) and then press OK on the Wireshark Packet Capture Options screen (we’ll not need to select any options here). Don’t yet press the “ Upload alice.txt file ” button. Use the Browse button in this form to enter the name of the file (full path name) on your computer containing Alice in Wonderland (or do so manually). Store this file somewhere on your computer. Go the labs/alice.txt and retrieve an ASCII copy of Alice in Wonderland. References to figures and sections are for the 7 th edition of our text, Computer Networks, A Top-down Approach, 7 th ed., J.F. Of course, we’ll be running Wireshark during this time to obtain the trace of the TCP segments sent and received from your computer. We’re using the POST method rather than the GET method as we’d like to transfer a large amount of data from your computer to another computer. You’ll do so by accessing a Web page that will allow you to enter the name of a file stored on your computer (which contains the ASCII text of Alice in Wonderland ), and then transfer the file to a Web server using the HTTP POST method (see section 2.2.3 in the text).
Ĭapturing a bulk TCP transfer from your computer to a remote serverīefore beginning our exploration of TCP, we’ll need to use Wireshark to obtain a packet trace of the TCP transfer of a file from your computer to a remote server. We’ll also briefly consider TCP connection setup and we’ll investigate the performance (throughput and round-trip time) of the TCP connection between your computer and the server.īefore beginning this lab, you’ll probably want to review sections 3.5 and 3.7 in the text 1.
We’ll study TCP’s use of sequence and acknowledgement numbers for providing reliable data transfer we’ll see TCP’s congestion control algorithm – slow start and congestion avoidance – in action and we’ll look at TCP’s receiver-advertised flow control mechanism. We’ll do so by analyzing a trace of the TCP segments sent and received in transferring a 150KB file (containing the text of Lewis Carrol’s Alice’s Adventures in Wonderland ) from your computer to a remote server. In this lab, we’ll investigate the behavior of the celebrated TCP protocol in detail.
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