HTTP protocol

I was reading today how a security problem could be using HTTP as an attack vector to the server. However, we will focus next week on the basic inner working mechanisms of HTTP 1.0 an 1.1 versions. If you already read section 2.2 of the textbook, no further reading is needed.

I hope you all have installed and tested Wireshark program to capture your very own HTTP traffic your computer sends and receives when browsing the 'net. The video below details some of the information you can obtain by capturing HTTP traffic.

Third lecture

Section 1.4 from the textbook was presented (unannounced during second lecture). Next lecture recommended reading is section 2.2 from the textbook. For the reading impaired I have found there is a video of the lecture too. World Wide Web service will be presented as our first case of distributed application. Most likely we will use a couple of lectures to cover the whole thing.

For reviewing Chapter 1 content I have also found Professor Todd Booth video content interesting.

Homework exercises due next Friday

R1. What is the difference between a host and an end system? List the types of end systems. Is a Web server an end system?

R2. What is a client program? What is a server program? Does a server program request and receive services from a client program?

R3. Why is it said that packet switching employs statistical multiplexing? Contrast statistical multiplexing with the multiplexing that takes place in TDM.

R4. How long does it take a packet of length 1,000 bytes to propagate over a link of distance 2,500 km, propagation speed 2.5 · 108 m/s, and transmission rate 2 Mbps? More generally, how long does it take a packet of length L to propagate over a link of distance d, propagation speed s, and transmission rate R bps? Does this delay depend on packet length? Does this delay depend on transmission rate?

Second lecture

Next Friday Chapter 1 will be finished and we wil start Chapter 2: The Application Layer that will
cover different types of distributed applications commonly used on the Internet (like World Wide Web, e-mail or Domain Name System). Please read section 2.1 of the (5th Ed) Kurose's Computer Networks for next class. Do make any question you have a as a comment to this blog entry.

Summarizing today's class you can read sections 1.1, 1.2 and 1.3 of the same book.

I forgot to mention that you can reach me at my office 2N6, building 1G, by appointment.

Please note Labs will not start till Tuesday October 14th due to the course structure (15x 2h lectures + 10x 1.5h labs each term).

Welcome to the 2014-15 Computer Networks course

Next Friday we are starting the new course. Information will be provided then about all you may care about the subject: program, assessment, passing requirements, etc.

It seems this year we are a smaller group than last year though you have two choices for the labs. Apparently the school expected the group to grow but it shrink instead.

Anyway, see you all in the classroom next Friday September 12th.