CS485/ECE440: Homework 6
November 20, 2008
General
•This homework is (mostly) about material covered in Chapter 5, 6 and 7 of the text
book.
•The answers to this homework are due December 2, 2008.
•Submit via e-mail to riesen@cs.unm.edu (Mail it before class on the 30th.) Your
subject line must say: “Homework 6 Submission” (and nothing else).
•Your answers to the questions below must be in a PDF or plain text file attached as file
named Homework6.pdf or Homework6.txt according to its format. (Not Hwk6.pdf,
and no Microsoft Word or image files, such as jpeg, please.)
•Keep your answers (and programs) succinct.
•Obey the University rules on plagiarism. In particular, do use libraries and the web
to find information you need to answer the questions, but do not copy whole answers
or programs. Reference your sources. The work you turn in must be your work.
Exercise 1: Silly window syndrome [10 points]
Briefly explain what the silly syndrome is. What algorithm is used to prevent the
syndrome from happening? How does that algorithm work, and what are some of the
problems associated with it?
Exercise 2: TFTP [30 points]
TFTP is a simple file protocol. It is sometimes used to boot systems remotely. The
booting machine sends out a TFTP request and a server responds with a kernel image that
the client uses in the second stage of the boot.
Request For Comments (RFC) are documents that describe protocols and procedures
used on the Internet. RFC 1350 describes TFTP. Look at RFC 1350 and answer the
following questions:
1. Why would one use such a simple protocol running on top of an unreliable data link
layer protocol such as UDP?
2. TFTP does not use a sequence number in its header. How does TFTP avoid duplicate
packets?
3. How does TFTP know it has received the entire file?
1
