15-441 Study Problems

This is a list of problems from the book that you may find useful in understanding the material from class and for studying for the exams. These are not required and will not be graded, though you're more than invited to discuss the problems with the TAs or instructors during office hours, or with your peers. The list isn't comprehensive and is still a bit of a work in progress.

Internetworking concepts

• Bridges: Ch3 p17
• Spanning tree algorithm: Ch3 p13, P22
• Longest-prefix match: Ch4 p22
• Subnetting: Midterm 2005 part B
• Fragmentation: Ch4 p10
• Layered addressing: Ch4 p12, Midterm 2005 part C
• Virtual Circuits: HW3 problem that you haven't seen yet. Looks a lot like Ch3 problems 4 and 5
• DNS: Ch9 p1, p2 p3, p11, p12 (some overlap, but they're fun questions to think about. :)
• HTTP: Ch9 p22
• HTTP+DNS: Ch9 p27 (may be easier / make more sense after the Web+Caching+CDN lecture)
• Architecture + TCP (easier after this week's lectures): Ch9 p36

Wireless networks: what's hard and what are the problems?

The most important things to take from today's lecture were:

• Why does TCP perform poorly on wireless links?
• How can we fix it?
• What are the hidden terminal and exposed terminal problems?
- How can we fix them?
• Why do link-state and distance vector protocols not work well in the ad hoc context?
• What does DSR do to solve these problems?
• (Understand DSR at a high level).
• Two capacity analyses of multi-hop wireless networks:
  • A chain of forwarders (1/3rd - understand why!)
  • A dense network (1/sqrt(n)).
• - The constraints and opportunities in sensor networks

The book doesn't have a lot of material on these subjects outside of chapter 2.8. If people are interested in ad hoc networks, a good starting point is a paper from MIT's roofnet project.

For sensor networks, see CMU's IrisNet project or the Berkeley Mote papers.

For TCP and wireless, see A Comparison of Mechanisms for Improving TCP Performance over Wireless Links. It's from 1997, but it hits most of the high points.

Last updated: Thu Apr 22 16:25:46 -0400 2010 [validate xhtml]