Networks +

To get an even better understanding of today's lecture, I am introducing you to what we can call the main info base of Internet protocols : The RFCs.

RFC 1180 is a tutorial on some of the basic concepts that we've covered in the past two lectures. Basically how the APPLICATION>OS>HARDWARE stack interacts with ethernet and IP. Let's go through some of the comments made and information provided by the RFC.

Just take note that we can assume a datagram and packet and frame are the same. However, we would want to use frame as link-level description (i.e. we say an ethernet frame).


"

2.6  Physical Network Independence

  IP hides the underlying network hardware from the network
  applications.  If you invent a new physical network, you can put it
  into service by implementing a new driver that connects to the
  internet underneath IP.  Thus, the network applications remain intact
  and are not vulnerable to changes in hardware technology. "

Take note of the following questions presented by the RFC:
"
2.8  After the Overview

  With the background set, we will answer the following questions:

  When sending out an IP packet, how is the destination Ethernet
  address determined?

  How does IP know which of multiple lower network interfaces to use
  when sending out an IP packet?

  How does a client on one computer reach the server on another?

  Why do both TCP and UDP exist, instead of just one or the other?

  What network applications are available? "

This is a brilliant analogy of networks:

"

3.1  A Human Analogy

  A good analogy of Ethernet technology is a group of people talking in
  a small, completely dark room.  In this analogy, the physical network
  medium is sound waves on air in the room instead of electrical
  signals on a coaxial cable.

  Each person can hear the words when another is talking (Carrier
  Sense).  Everyone in the room has equal capability to talk (Multiple
  Access), but none of them give lengthy speeches because they are
  polite.  If a person is impolite, he is asked to leave the room
  (i.e., thrown off the net).

  No one talks while another is speaking.  But if two people start
  speaking at the same instant, each of them know this because each
  hears something they haven't said (Collision Detection).  When these
  two people notice this condition, they wait for a moment, then one
  begins talking.  The other hears the talking and waits for the first
  to finish before beginning his own speech.

  Each person has an unique name (unique Ethernet address) to avoid
  confusion.  Every time one of them talks, he prefaces the message
  with the name of the person he is talking to and with his own name
  (Ethernet destination and source address, respectively), i.e., "Hello
  Jane, this is Jack, ..blah blah blah...".  If the sender wants to
  talk to everyone he might say "everyone" (broadcast address), i.e.,
  "Hello Everyone, this is Jack, ..blah blah blah...". "

There are RCFs on literally hundreds of protocols and technologies. www.faqs.org should have all of them. The only problematic thing about RFCs is that they are referenced by number and not title. but getting the number of an RFC is simple, just google it.

Please click on the link below to be taken straight to the RFC1180.
[Overview of TCP/IP ]

Ah, these bubbles are so awesome. Ok. First off, let's start thinking about the Internet. If you're still a bit lost after todays lecture, take a look here : http://en.wikipedia.org/wiki/Internet

The first few chapters deal with Ethernet, which we find on a local area network. I've found a few links to give you perhaps a bit more information:

On Local Area Networks: http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/introlan.htm

Ethernet : http://computer.howstuffworks.com/ethernet.htm

Comment on this post if you have found any more useful links!

Laters :)