T-110.300 Telecommunications architectures

Extra homework assignment

Learning goals: The student will review the most important data transmission technologies and how they co-operate. The student will also practice writing a short technical report on a specific issue, which he or she is quite likely going to do in the future, too.

Deadline: Return the written report to the T-110.300 mailbox (CS building, near room A112) by 11.2.2005, 12am.

You can submit this assignment, if

• You have passed at least 5 homework rounds AND
• You have more than 50 homework assignment points.

You should read and understand the whole assignment before you start.

Write a report about the relation of communications payload to the gross capacity of a transmission medium. Imagine that you are writing to a technical manager, who wants to know how much of the available bandwidth is actually used for user data and how much is used by the different protocols.

To write the report, you have to select and analyze a specific instance. During the work you must make decisions, like the size of the user data unit. Document these decisions and the reasons for them. (E.g. "I selected a picture file of 100 kB, because I felt it represents the average picture size")

Select a physical network medium for analysis, for example a PDH or SDH E-1, ATM or ADSL connection. Use your own judgement on selecting the physical medium, but if you try to make the assignment trivial by selecting something way too simple, it will not be accepted. If you're unsure about your selection, please contact course staff in good time before the deadline. Find information about the actual bit rate used in the connection on the physical layer. Internet operators and equipment manufacturers are a good source for this. Document your sources.

Analyze the framing method and other protocols up to the IP layer used and how much overhead each protocol produces. There might be multiple protocols underneath the IP layer.

Select a few data samples to be analyzed, for example a smallish web page with text, a picture file and so on. Your samples should represent different instances of data transmission.

Analyze the TCP and applications layer protocol overhead, including the opening and closing sequences and the growth of the sending window. You may assume that there are no errors or dropped packets. HTTP is the most usual applications level protocol, but you may select some other protocol, too.

Think about the data you have now generated and what it actually means. Draw some conclusions about your work. For example, is there a lot of overhead or a little? Is there overlapping functionality in the protocols and could the transmission system be made more efficient?

Now write a complete report, where you combine your findings and produce a summary of the whole issue. Your report should be at most 3 pages long. It should give the reader a clear understanding of how much overhead the different layers and protocols produce.

Grading: The report is graded pass/fail. To pass it must meet the following requirements:

• The report must be readable and answer the question "How much overhead the different protocol layers produce in data transmission"
• The report should be good enough language and concise enough that the assistant does not get overly bored when reading it. Writing an un-interesting report full of trivialities means failure. Too short is better than too long.
• There should be a nice drawing or a graph illustrating the amount of transmission path used by different layers or protocols with different types of data.
• There must be a personal analysis in the end where you document your thinking about the meaning of what you have just done.
• The sources used must be documented.
• All writing and pictures in the report must be yours, or clearly marked and attributed to a source. All the relevant parts must be your own work. Material from other sources should only be used in supporting role.
• If handwritten, the writing must be legible and the pictures of good quality.
• Languages accepted: Finnish, Swedish and English