Dec-05: Project 4 has been posted. Get going, because Project 5 -- the final one -- will immediately after!

Nov-11: Project 3 has been posted. Hop to it!

Nov-01: Of course, I failed to configure the submit command properly for this project. I believe I have now fixed that problem. Those who emailed submissions are in fine shape, although I will ask that you submit your work via cs28-submit also, just to preserve my sanity; I promise to your your earlier, email-based submission time in evaluating your work.

Oct-31: Happy Halloween! Project 2, parts A and B, are now available -- and it's a race, so get started! You can find the instructions for how to get going on the Assignments page.

Oct-21: Sitting outside my office, on the pin-board by my door, are your graded submissions for Problem Set 1. Please come and pick them up. After seeing the results, feel free to ask any questions that arise.

Oct-20: Although I was forced to cancel my earlier class today due to a migraine, I'm feeling better, and so our class will occur as usual at 2:00 pm.

Oct-17: An admonishment to me and to you: It is 2010, and we all, after struggling through a well established topic such as sliding windows, should use readily available resources to dispel our confusion. What do I mean? Use the Wikipedia, which is not always academic anathema, to find an article on sliding windows protocols.

You will find, if you read patiently, that my mistake was to state that the receiver would send an ACK only if the received frame were within the receivers window. That assertion was our downfall, and some of you made suggestions to fix my proprosed protocol along those lines -- you were right to do so. The correct protocol is that the receiver does indeed ignore frames outside of its window except to send an ACK for them. The safety of this action, which you should initially doubt, falls within Mr. Volz's observation that, given proper window sizings, the resend cannot be ambiguously interpreted as a new frame of the same number.

Armed with the nugget of important correction, reconsider the go-back-n and selective repeat protocols. Assuming f frame identifiers (where there are k bits used to label each frame identifier, such that 2^k = f), and assuming sender and receiver window sizes of w_S and w_R, respectively), how does that change our evaluation of relationship between window sizes and frame numbers? That is, what are the maximum values of w_S in relation to f for each protocol, and what can happen if that maximum is exceeded? We will seek to put these questions to rest, at long last, tomorrow, so be prepared.

Oct-16: Of course, I managed to overlook an important detail in setting up cs28-submit, leaving it working for those who have taken CS 26 before, but not working for those who haven't. Try it again, with apologies for those for whom it did not work last night.

Oct-15: At long last, the cs28-submit command should be installed. It should be in place on all of the department workstations, but if it does not work on yours, login to rigel and perform the command there, where it certainly should work.

Oct-02: I have created the groups, and group directories. On the CS department systems, you will find the group directories in /home/cs28/cs28X, where X is replaced by one of a through h, depending on which group to which you belong. All of your work should be done in these directories so that your partner(s) can share the work with you. Your groups are:

Sep-28: A reminder that you must send me an email indicating with whom you are working on the projects. If you do not have someone with whom to work, send me an email anyway to let me know, and I will address the issue. You must send me this email by tomorrow, 2:00 pm, before class so that I can complete the pairs and get you all to work with group directories.

Sep-26: Two previous Amherst College students have augmented their CS experiences with SISMAT, a summer program in which you train and intern on computer security topics at Dartmouth with various experts from academia and industry. You then follow up the summer experience with a special topics course (which I am happy to advise, although you could choose one of the other CS faculty as well). Check into the program, and feel free to ask me more about it. Also feel free to contact Nic Mollel and/or Adam Lerner (look them up on the Alumni Directory) to ask about their experiences with the program.

Sep-25: Project 1 on the data link layer has been posted. Dig into it. Also recall that you are working in groups for that project. Send me an email noting with whom you are working, and I will create some group directories so that you may more easily work with your partner. Those of you without CS department accounts should contact me to obtain an account immediately.

Sep-16: Problem Set 1, on the physical layer, has been posted on the assignments page. Hop to it!

Aug-24: Welcome to Networks and Cryptography! If you are enrolled in this class, or even if you are considering this class, please begin, before our first class on Wednesday, by reading the course information. This document makes clear what material we will cover, what is expected of you as a student, how I will evaluate your work, etc. It may also help you to determine whether this course is one that interests you.