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 of100 – 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

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

IP: 212.58.240.120

What a LAN might look like:

Print Server

WebServer

File Server

Router

Circuit: The pathway through which the messages travel

ClientComputers

HUB

Data Processing on Networks

• Host-Based Architectures

• Client-Based Architectures

• Client-Server Architectures

Host-Based ArchitectureClient (user) Terminals

Host (Mainframe computer)

Presentation LogicApplication LogicData access logicData storageProblems:

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

-Upgrades require big jumps and are expensive

Thin CLIENT

Client-based ArchitectureClient

(microcomputer)

Server (microcomputer)

Data storagePresentation LogicApplication LogicData 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

FAT CLIENT

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 LogicApplication 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 CableInner 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 TransmissionPROS-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 LANRouter

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/IPTransmission 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. Physical1010001011101000111010

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