Network

Network

What is Network?

Network is a group of connected computers connected by

Cables or any other media.

Network

Application of Network

- Resource Sharing

Hardware ( computing resources,disks, printers ... )

Software (Application Software)

- Information Sharing

Easy accessibility from anywhere ( Files, Databases, ... )

Search Capability ( www )

- Communication

Email

Message broadcast

Internet

What is Internet?

A global network of interconnected networks is called Internet.

internet connection

Growth of Internet

internet use

1977: 111 hosts on Internet

1981: 213 hosts

1983: 562 hosts

1984: 1,000 hosts

1986: 5,000 hosts

1987: 10,000 hosts

1989: 100,000 hosts

1992: 1,000,000 hosts

2001: 150 – 175 million hosts

2002: over 200 million hosts

Now (2016) , about 3,424,971,237 population of the planet are on the Internet

Network and Internet

How to differentiate Network from Internet?

network and internet

We can have network without Internet !

Internet is meaningless without network !

lan

Network Categories

LAN (Local Area Network) :

- Operate within a limited geographic area

- Allow many users to access high-bandwidth media

- Provide full-time connectivity to local services

- Connect physically adjacent devices

MAN (Metropolitan Area Network) :

- Interconnect users in a geographic area or region larger than

area covered by LAN but smaller than the area covered by a WAN

- Connect networks in a city into a single larger network

man

wan

WAN (Wide Area Network :

- Operate over large, geographically separated areas

- Provide full-time remote resources

connected to local services

- Provide e-mail, World Wide Web,

file transfer

WAN technologies e.g:

Modems

Network Data Transmission mode

Simplex :

simplex

Data can be transferred only one direction in medium

Example:

Radio: Just receives the signals

Remote Control of the TV.

Half-Duplex :

Data can be transferred both ways in the medium but in only one direction

half duplex

Example:

Wireless Radio

Full-Duplex :

Data can be Transferred in both directions simultaneously

full duplex

Example:

Telephone Communication

Network Data Transmission

Network connection Methods

Peer-to-Peer network :

Has no dedicated servers

There are no hierarchical differences between workstations in the network

All workstations are clients and servers at the same time

peer to peer

Client / Server network :

- Server-based Network has become the standard model for

networking

- The server provides services which clients need in network

- Centrally manage the usage of resources

Advantages:

client/server

. Centralized Administration

. Security and policy

applied by server

. Backup

. Monitoring

Network Devices

NIC (Network Interface Card)

NIC

- Interface for the computers to the network

- Each NIC has a unique hardware address

called MAC address (Physical address)

- connected to other network components

via a transmission media (e.g. cable)

Hub

- All incoming signal are passed to all ports

hub

- Attached devices divide the available

network bandwidth

Switch

- Intelligent HUB

switch

- Solves traffic problems

- Improves network performance

- Works with MAC Address

Repeater

– Receives electrical signals, amplifies them and passes them on

– Bidirectional signal amplification

– Enables long cable stretches

repeater

Bridge

- Connects separate two network segments

bridge

- Similar to repeater

- Addressing with the MAC Addresses

Router

router

- Connect networks

- Connects different networks which

work with the same protocols

- Important Information for routing

are stored in the Routing tables

- Contain IP Table

Network Topologies

BUS

- One cable connects multiple computers

- T-Connectors are used

- One computer can transmit data at a time

- A central cable (coaxial cable)

- All attached stations are affected by disturbance at the central cable

BUS

STAR

STAR

- All computers are connected

through central hub or Switch

- Each computer has separate cable

- Fault tolerance

- Most Used Topology

Mesh

- Each device/PC is connected to every

Mesh

other device/PC

- Each connection needs its own cable

- Highest fault tolerance

- Expensive topology

CN= Cable Needed , D = Device

CN = (D * (D-1)) / 2