Transcript How the Internet Works

How the Net Works
A Very Brief
Introduction
We will talk about…
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What makes up the Internet
How the WWW functions
What is it?
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The Internet: “Everybody’s 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.
What are some characteristics of
the Internet?
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It is decentralized
It is (generally) packet-switched
It is hardware independent
It (generally) uses client-server architectures
Network Topology
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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.
Packet-Switching
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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.
Hardware independent
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A TCP/IP stack can be created for just about
any computer/communication device.
Just about anything can carry a TCP/IP
message.
Client-Server Architecture
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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.
Typical Web Request
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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.
Internet Applications/Servers
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The TCP/IP Stack
Ping
Mail
Usenet
FTP
Chat (IRC, ICQ)
Web
Others: DNS, Voice, Quake, Napster, etc.