Notices

This page contains general notices for Computer Networks.


Decenber 3, 2014 - The instructions as they will appear on the final exam are: Decenber 3, 2014 - See here for the green networks slides.

November 30, 2014 - See here for an email sent to all USF faculty regards administration of the ExploranceBlue student evaluations. I will give time on Wednesday for this.

November 25, 2014 - I have changed the paper review assignment to now say "should preferrably come from ICC..." instead of the orginial "must come from ICC..." with respect to where your papers should come from.

November 8, 2014 - Being able to describe an alorithm (and not just implement it in code) is very important. Flowcharts are one way to describe an algrothim (and are still widely used in patents). A description of how to use pseudocode to describe algorithms is here.

November 5, 2014 - Someone said something about ENB and icicles... well it could happen, see here.

November 2, 2014 - Many of you are getting started on the paper review assignment here. This is great that you are getting an early start on this assignment and digging in to the literature. The purpose of this assignment is to let you dig into topics (related to networks, of course) of interest to you. Also, this assignment is there to help you understand the "better principle" that drives Computer Science (and Engineering as a whole). You need to find two papers such that the later (in date) paper improves upon the earlier paper - i.e., it develops and evaluates a "better" method by some measure of interest. An example of this from one of my past M.S. students is here with the work he improved upon here.

November 2, 2014 - A spreadsheet to show you how to calculate confidence intervals is here. I suggest reading Wikipedia here and here to understand what you are doing (and note some of the cautions for comparing data sets).

October 26, 2014 - In problem #8 in the mid-term exam the solutions (here) show 4 points for the CMTC. However, the problem does not explicitly ask for a CTMC. If you got 4 points marked-off the not having a CTMC, show your exam to me for possible grade adjustment.

October 17, 2014 - There is an error in the exam solutions for the mid-term exam fall 2012. For Problem #8 the CTMC transition rates should be 4 from state 2 to state 1, and 2 from state 1 to state 0.

October 12, 2014 - The instructions as this will appear on the Midterm Exam are:

October 2, 2014 - The Kleinrock paper review slides are now posted here. We are now if the textbook, which can be purchased from the bookstore (I do believe still), from Amazon here, or (apparently) accessed online from the USF library "for free" and read online. Next week will will cover Markov modeling leading us into queueing theory.

September 25, 2014 - We discussed the "better principle" in class. A discussion of this principle in CRN is here. Several of you have asked about how to write papers. You need to read Zobel's Writing for Computer Science. This is really a book on how to do research - research and writing go hand-in-hand.

September 24, 2014 - On Friday you will demo your mini-project #1. Your demo will entail:

  1. Allow the TA to briefly inspect your source code and then you build your executables while he watches. If for some reason this is not possible, let me know why.
  2. Bring-up your server on machine #1
  3. Bring-up one client on machine #2 and register it with the server. The registration should be done at the client user interface (i.e., not by the user at the server). The client should display messages every DELAY seconds (make DELAY = 10). The messages should change in a predictable manner (e.g., contain a count).
  4. Bring-up a second client on machine #3 and register it with the server. The registration should be done at the client user interface (i.e., not by the user at the server). The second client should display messages every DELAY seconds (make DELAY = 10). The messages may be synchronized between the two clients (that is, the arrival of the first message after registration can occur in any time less than DELAY seconds, subsequent message must be every DELAY seconds).
  5. Be able to demonstrate handling of packet loss for a 25% loss rate after a successful registration. Show the TA the code you are using to emulate packet loss.
  6. Be able to demonstrate the system given 100% packet loss occurring after a successful registration.
  7. Quickly walk-through your source code with the TA
A hint: It should go without saying that for fairness to everyone all code and other submissions must be "frozen" at 5pm. Also, everyone gets one 20 minute slot and no more. When your demo clock has started, you have 20 minutes and no more. What is most important is fairness to all students.

September 21, 2014 - Thanks to a student in the class we now have a nonblock UDP client that works for both Windows and Unix, see udpClientNonblock.c.

September 21, 2014 - I have received two questions on the timing of the messages (this for mini-project #1). It is not a requirement that the first message after registration be received DELAY seconds later. In other words, you can synchronize the sending of all message to the currently registered set of clients. For example (assume here that DELAY is 10 seconds), if I register at time 0 and you register at time 3, it is acceptable it we both received our first message at time 10 (and then the second at time 20, third at time 30, and so on).

September 19, 2014 - There is a bind() in udpServer.c but not in udpClient.c. The bind is needed to accociate an address and port number to the server_s socket for a client to be able to send a message to udpServer.c. Once a client has sent a message, udpServer gets the client address and port from the message and then can use this to send a message to the client. This is discussed in the remarks sections of the MSDN entry for recvfrom(), see here.

September 19, 2014 - Some of you may find it useful to have a non-blocking recvfrom() for implementing your protocol for mini-project #1. An example program for non-blocking sockets is udpClientNonblock.c (this only works for Winsock now, if you can get this to work for BSD sockets please email to me the solution). In Winsock an additional error code (beyond the "-1" from a failed sockets function) can be returend with a WSAgetlasterror() call. An example of this is udpErrorDemo.c.

September 19, 2014 - Some of you may find it useful to have a non-blocking recvfrom() for implementing your protocol for mini-project #1. An example program for non-blocking sockets is udpClientNonblock.c (this only works for Winsock now, if you can get this to work for BSD sockets please email to me the solution). In Winsock an additional error code (beyond the "-1" from a failed sockets function) can be returend with a WSAgetlasterror() call. An example of this is udpErrorDemo.c.

September 14, 2014 - We are about a half to one week "behind schedule" based on the course outline. This does not impact any of the mini-projects (I made the due dates such that a schedule could be accomodated). As of last week all material needed for mini-project #1 was covered. On Monday, September 15th I will answer any/all questions from last week's material and discuss the mini-project #1 in detail. Key topics coming up this week are layer 2 (notably CSMA), the Abrahmson ALOHA analysis (from his 1970 paper in your reading), and the Metcalfe Ethernet analysis (from his 1976 paper in your reading).

September 4, 2014 - We discussed the Wireshark tool today. This is a useful tool for research. The definitive statement on use of IT resources at USF is here.

August 31, 2014 - This week we will be covering the sockets interface in class. I will be using "C" as the language to teach sockets, but everything we do in class could easily be done in Python or Java as well. Now is the time to be sure that you have a working programming environment. I do recommend "C" and command line. To see how to build a sockets program in "C" click here.

August 26, 2014 - The "Warriors of the Net" video is here.

August 25, 2014 - Welcome to a new semester!

Last update on December 3, 2014