How%20the%20Net%20Works

1
How the Net Works

• A Very Brief Introduction

2
We will talk about

• What makes up the Internet
• How the WWW functions

3
What is it?

• The Internet Everybodys computers, connected.
• A set of rules, or protocols, that allow
  different kinds of machines on different kinds of
  networks to talk to one another.
• The structures that emerge and are anticipated by
  these rules.

4
What are some characteristics of the Internet?

• It is decentralized
• It is (generally) packet-switched
• It is hardware independent
• It (generally) uses client-server architectures

5
Network Topology

• There is no center of the Internet
• There need not be a tree-like hierarchy
• In fact, there are central backbones that carry
  most of the internet traffic, but this is as much
  an economic as a technical characteristic.

6
Packet-Switching

• Messages cut into sections of a standard size,
  affixed with a header explaining where they
  should be, and set out onto the net.
• This is very good for reliability.
• This is not-so-good for speed or efficiency.
• Traceroute programs allow you to seen how many
  bounces take place.

7
Hardware independent

• A TCP/IP stack can be created for just about any
  computer/communication device.
• Just about anything can carry a TCP/IP message.

8
Client-Server Architecture

• In most interactions on the net, one computer
  (yours!) acts as a client, while another acts as
  a server.
• The client requests a service, and the server
  delivers it.
• Simple, but important element of many
  applications on the Internet.

9
Typical Web Request

• Client asks for the address of the host from a
  domain name server.
• It then sends a message to that address, attn.
  Port 80 usually, asking for a particular web
  page.
• The server sends the page and waits for another
  request.

10
Internet Applications/Servers

• The TCP/IP Stack
• Ping
• Mail
• Usenet
• FTP
• Chat (IRC, ICQ)
• Web
• Others DNS, Voice, Quake, Napster, etc.