INT20CN Computer Networks -- Assignment 2, 2001

La Trobe University, Bendigo

Department of Information Technology

INT20CN: Computer Networks

Assignment 2, 2001

Your task in this assignment is to investigate one only of the following topics in computer network architecture, and submit a report on your findings. Note that all of the topics are about, or related to, application-level protocols in the Internet. Each of the topics has a "theory" section, where you have to look up the information somewhere (presumably on the Web, or in an RFC), and a "practical" section where you have to demonstrate how the particular system under discussion actually operates in practice. You must complete both sections to gain a high mark.

Note also that additional topics might appear on this page as they are suggested to me. It could be worth checking back regularly if you don't like any of those given below.

Caching Proxy Servers

Theory: In the lectures, some of the HTTP/1.1 cache-management features were discussed. At most sites (including La Trobe), HTTP access to the "outside" Internet is via a Caching Proxy Server. The software which is used for this at La Trobe (and many other organisations) is called squid. Find out about this software, and discuss briefly how it can be used to implement distributed caching.
Practical: How effective is La Trobe's proxy server? Use telnet (as described in the lectures) to GET some external Web pages via the proxy server (NB: port 8080 is used for the proxy function). Can you tell if the page was cached? How? What other HTTP/1.1 headers are present?

USENET (Newsgroups)

Theory: Investigate (briefly!) the Network News Transfer Protocol (NNTP) in the usenet news system. NNTP is the basis of usenet and has many interesting features.
Practical: Use telnet to connect to a nearby news server -- within La Trobe,news.latrobe.edu.au is available. Most NNTP servers support a "HELP" command so you can easily discover what features they offer. Use the protocol to learn what newsgroups are carried on the news server, to obtain a list of article headers, and to deliver an article. If you're really keen, try using the protocol to post an article to one of the "test" newsgroups (eg, latrobe.test).

POP

Theory: Investigate the POP3 protocol. What is it used for? What other alternatives are available to achieve the same purpose? How does it handle authentication?
Practical: Use telnet to connect to a POP server. If you're on a La Trobe campus, you can probably use students.latrobe.edu.au. Exercise some of the protocol features mentioned in the "theory" section.

FTP

Theory: Investigate FTP. Find out the answers to mysteries like: "What is FTP used for?", "What is the PORT command used for?" "What is the difference between text and image (binary) modes?", "What is the difference between active and passive mode?"
Practical: See what FTP control protocol messages you can send (and receive) using telnet. Explain why you can't fully debug FTP using telnet alone.

Other

Any other appropriate application protocol-related topic with the explicit prior approval of the lecturer.

You should expect to write something around 1500 words on the topic of your choice, although this is not mandatory. You can submit your assignment using either traditional hard copy (paper) form, or as an email attachment of MIME type text/html sent to cnsubmit@ironbark.bendigo.latrobe.edu.au, as for the first assignment. Your choice of submission format will not affect the mark gained for your assignment. Submissions must, as usual, adhere to the requirements of the La Trobe University, Bendigo Assignment Guide.

This assignment carries 15% of your mark for Computer Networks.

Due Date:11th May, 2001

Lecturer: Phil Scott, 5444 7277, p.scott@latrobe.edu.au.

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