Transcript PowerPoint 97 slides

How Does the Internet
Work?
The Internet Worldwide
Net America
Not to actual
size!
Nodes
The Internet
From Home
To connect from
home you need:
• computer
• modem
• Dial-up software
(if using phone)
• ISP
Client
ISP
What is an ISP
How does it work?
Server
Eudora
28.8 to 56K
Netscape
WS-FTP
smtp/pop
http
ftp
T1 to T3
~1,500K
Servers have software
loaded that allows them
to perform select
functions
Pop - E-Mail
Ftp - transfer files
http - web pages
Server
Surfing
router
servers
client
• Client talks to the
Server
• The request is directed
by routers
• The requested
information is found
and routed back to the
server that sent the
request, which sends it
to the client.
• IP addresses are used to
route the information
Surfing
router
servers
client
• Each server has a unique IP address
• 164.156.254.55
• ISPs usually use session IP addresses
that change each time you log on.
• Domain name - human readable
names that correspond to IP addresses
• for example: www.niu.edu =
164.156.254.55
• Internic - controls the distribution of
domain names
Surfing
• The browser breaks the URL into 3 parts: 1) The protocol
("http"), 2) the server name ("www.chipheath.com"), and 3)
the file name ("home.htm").
• The browser communicates with a name server to translate
the server name "www.chipheath.com" into an IP Address
that it can use to connect to that server machine.
• Following the HTTP protocol, the browser sends a GET
request to the server asking for the file “home.htm” at
“www.chipheath.com”
• The server returns the HTML text for the web page to the
browser.
• The browser reads the HTML tags and formats the page
onto your screen.
Networks
NIU
Engineer
Admin
student
LAN
COB
Library
Grad
School
• NIU has its own Local Area Network (LAN) that
provides information to those inside the network and
some outside access
Networks
MOTOROLA
ACCT
dealers
Prod
INTRANET
admin
Controlled
outside
connection
sales
web
site
• Motorola has its own network called an intranet.
Users in Motorola are the only ones with access to
critical information.
Networks
MOTOROLA
ACCT
dealers
Prod
INTRANET
admin
sales
web
site
• If there is outside connection, there must be security.
• This protection is called a firewall