WHAT IS NETWORKING?

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8 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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WHAT IS NETWORKING?

Networking is …

How computers talk to each other

Overview of Today


Types of Networks



Data Processing on Networks



Communications Circuits



Communications Devices



TCP/IP Protocol and Routing


Types of Networks

LAN (Local Area Network)


Local area networks usually occupy a room or building, and
typically include a group of PCs that share a circuit. Support
data rates of 10 to 100Mbps.

Types of Networks

MAN (Metropolitan Area Network)

Air Force Base

San Francisco
Executive Airport

Sacramento Army Depot

Capitol Building

Office of Public
Works

MANs usually span 3
-
30 miles and can support data rates of

100


1000Mbps.

Types of Networks

WAN (Wide Area Network)

Seattle

Sacramento

Los Angeles

Phoenix

Chicago

New
York

WANs span hundreds or even thousands of kilometers. Leased circuits or
other commercially available services are used to transmit data. Supports
data rates of 28.8 Kbps


2Gbps.

These different types of networks
are linked together!

WAN

MAN

MAN

MAN

MAN

LAN

LAN

LAN

LAN

WANs are interconnected too

WAN

WAN

WAN

WAN

WAN

Example

Trace Route to http://www.bbc.co.uk/

IP: 212.58.240.120

What a LAN might look like:

Print
Server

Web

Server

File
Server

Router

Circuit:

The pathway
through which the
messages travel

Client

Computers

HUB

Data Processing on Networks



Host
-
Based Architectures



Client
-
Based Architectures



Client
-
Server Architectures

Host
-
Based Architecture

Client (user)
Terminals

Host

(Mainframe computer)

Presentation Logic

Application Logic

Data access logic

Data storage



Problems:

-
All processing is done by the host which creates a
bottleneck

-
Upgrades require big jumps and are
expensive


Client
-
based Architecture

Client
(microcomputer)

Server
(microcomputer)

Data storage

Presentation Logic

Application Logic

Data access logic

Problem:

All data must travel between server and clients


Why is this a problem?

It creates
network congestion

that can cause poor network performance

Client
-
Server Architecture


More
efficient


More
reliable


Allows hardware and software from
different servers to be used together.

Client
(microcomputer)

Server
(microcomputer)

Data Access Logic

Data storage

Presentation Logic

Application Logic


Bandwidth


WHAT IS IT?

Twisted Pair


Most Commonly used


WHY are they twisted?


Two Types


Shielded:


Difficult to Install and use


More expensive


Unshielded:


Easier to Install


More susceptible to Interference

Twisted Pair Pros and Cons

PROS


-
Inexpensive

-
Easy to get

-
Flexible and lightweight

-
Easy to work with

CONS


-
High interference

-
Signal weakens over
time

-
Relatively low
bandwidth

Coaxial Cable

Inner Conductor


Insulator


Wire mesh (ground)


Outer protective shell

TV companies use coaxial cable between
community site out to businesses and
telephone poles between users.

Coaxial cable was
invented in 1929 and
first used
commercially in 1941

Biggest difference
between coaxial and
twisted pair is that it is
better shielded

Coaxial Cable

PROS


-
Higher bandwidth



350
-
600MHz


Up to 10,800 voice

conversations

-
Easy to work with

-
Less interference than
Twisted Pair

CONS


-
Signal strength wanes
fairly quickly over
distance

-
Expensive over long
distances

-
Bulky

Fiber Optic Cable

Plastic Jacket


Glass Cladding


Fiber Core

Fiber in the real world

Fiber Optic Cable

PROS


-
Greater Capacity

-
Data rates of up to 2Gbps

-
Strong signal over distance

-
Small and lightweight

-
Immune to electromagnetic
interference

-
Good security

CONS


-
EXPENSIVE

-
Difficult to install

Fiber Optic Cable is THE FUTURE!



Want to learn more? There are tutorials on
the web:


http://www.iec.org/online/tutorials/fiber_optic/


http://www.arcelect.com/fibercable.htm

Wireless

To Internet

Wireless


Balmer!



Popular in LAN use


WHY?




What are possible cons?

Flexibility!

Cost: No wires to install!

It’s fast!

Security

More Interference


what does this mean?

Satellite Transmission

PROS

-
Can reach a large
geographical area

-
High bandwidth

-
Cheaper over long
distances


CONS

-
High Installation Cost

-
Interference from lots of
factors, including weather


Another look at the LAN

Router

HUB

or
Switch?

HUB


Old technology


Stupid, why?

Broadcasts to all computers on the network,
which creates unnecessary traffic

Switch


Does everything a HUB can do, but it’s
smarter


Forwarding Tables allow switches to send
messages directly to the computer who it’s
supposed to go to

Switch

















































































































































Kim

Ron

Meg

Amy

TCP/IP

Transmission Control Protocol/Internet Protocol


What is it?

A Protocol! Yeah, but what does that mean?

A Language that computers use! We use English, they use TCP/IP


What does it look like?

111.111.111.111


4 octet number

All computer must have an IP address to use the Internet. Why?

It’s the address of the computer, just like you have a street address

TCP/IP

128.95.230.3

128.95.230.54

128.95.230.80

128.95.230.100

140.142.200.100

140.142.200.95

140.142.200.34


OSI Model

7. Application

6. Presentation

5. Session

4. Transport

3. Network

2. Data Link

1. Physical

7. Application

6. Presentation

5. Session

4. Transport

3. Network

2. Data Link

1. Physical

1010001011101000111010

Suzy

Rachael



Application Layer



Internetwork Layer



Hardware Layer


How packets move across the
Internet

Asynchronous Packet Transfer


Out of order


How does the computer know what order
they should be in?


There is a header on each packet


Why is this good?


Each packet can find the fastest way (not
necessarily the most direct way)


Synchronous Packet Transfer