Transcript PowerPoint Presentation - Super Saturday Internet Course

Internet Review
Academic Talent Search
All About Networking
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Devices
Packet Transfer
Hardware
Software
Wiring/Cabling
Protocols
And much much more!
What is a Network?
What is a Network?
Lots and Lots of wire. To get information from one machine to
another we must connect a wire between them. One machine
talks while the other listens, and vice-versa.
Sharing the wire.
Instead of running a wire from every machine to all the other
machines we share a single wire amongst them. One
machine talks while all the others listen.
Taking turns.
All machines agree to only use the wire for a short burst
of information (a packet) and then let someone else
have a chance.
This agreement on how to pass information on the wire
is called a protocol.
Collision.
If two machines start to talk on the wire at the same time, no one
can understand what they said. We call it a collision.
Collision (cont.)
Both machines can tell that they interrupted each other so they
“back off” for a small amount of time and try again.
Too much information!
Lets say we have ten machines sharing a wire and they can talk
for 1/100th of a second for each packet. If everyone is talking
then they can say something every 1/10th of a second. Not a
problem.
Too much information (cont.)
But what happens when you have 1000 machines on a wire?
They can only talk every 10 seconds! Not good!
Too much information! (cont)
To keep down the amount of talking on a wire we separate wires
with routers. The router listens to all the packets on one wire
and passes on only the packets destined for someone on the
other wire.
Router
Routers
Routers are used to connect two or more networks together to
logically form a bigger network.
Internet
Cloud
How far away is it?
When a packet of information goes from one network to another
it “hops” through the router. We use hops to tell distance.
http://www.monitis.com/traceroute/
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What is in a packet?
TCP/IP Protocol:
• DESTINATION IP ADDRESS
• ORIGINATING IP ADDRESS
• HOP COUNT
• SIZE
• CHECKSUM
• DATA
So what is the Internet?
So what is the Internet?
A network of millions of networks with
hundreds of millions of devices, maybe
even billions. Nobody really knows!
IP Address.
Each device on a network has a unique
address to tell it apart from all the other
machines. For the TCP/IP protocol the
address is four numbers separated
by periods (130.86.90.1).
Even coke machines and coffee pots
can have addresses!
http://whatismyipaddress.com/
Domain Name Service
The phonebook of TCP/IP. We like to use names instead of
numbers. The DNS keeps a record of host names and
numbers. DNSlookup.com and select Lookup or Reverse
Lookup. URL: Let’s compare to your postal address.
www.aol.com
152.163.202.70
Domain Name
Server
How it works LOGICALLY
We have looked at how things interconnect at a
physical level. Wires, routers, packets. Once
everything is connected physically we can setup
networks into a logical space to make things easy to
use. No matter where in the world a machine is
connected, we can talk to it.
HOST or CLIENT
Any machine connected to a network, from simple desktop
machines to giant mainframes with thousands of users.
SERVER.
A host that provides a network service. Services can be e-mail
systems, document archives, web sites. A program runs on a
server to allow CLIENTS to connect and make requests.
You might create a web site on your computer but you transfer it
to a server and people access it from the server!
So what is the World Wide Web?
So what is the World Wide Web?
A specific protocol allowing communication
via text, images, video, audio, etc.
The World Wide Web is NOT the Internet.
Imagine the Internet is just infrastructure to
allow all forms of transportation.
The WWW is just a specific type of
transportation, like the rail system.
Text, images, sound, etc. are just hitching
a ride on the trains on the railway.
What is a Web Site?
What is a Web Page?
What is a Homepage?