Information and communication technology fundamentals
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Information and Communication Technology Fundamentals. Credits Hours: 2+1. Instructor: Ayesha Bint Saleem. NETWORKS - I. Presentation Credits. “Introduction to Computers”, Peter Norton “Computer Networks”, Tanenbaum Dr Altaf Khan, Virtual University.

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Information and communication technology fundamentals

Information and Communication Technology Fundamentals

Credits Hours: 2+1

Instructor: Ayesha Bint Saleem


Networks i

NETWORKS - I


Presentation credits

Presentation Credits

  • “Introduction to Computers”, Peter Norton

  • “Computer Networks”, Tanenbaum

  • Dr Altaf Khan, Virtual University


Information and communication technology fundamentals

Networks is a set of technologies – including hardware, software and media – that can be used to connect computers together, enabling them to communicate, exchange information and share resources in real time


Example

Example

  • Web Browsing application

    • Software

  • Protocols involved

    • Software

  • NIC / Modem

    • Hardware

  • Telephone line / Co-axial cable / Air interface

    • Media


Information and communication technology fundamentals

Why do you want to have Networks?


Uses of networks

Uses of Networks

  • Sharing Resources

    • 1 printer , many people wanting to print

    • Access to same data and programs

      • Servers

  • Personal Communication

    • Email

    • Audio/Video/Data Conferencing


Uses of networks1

Uses of Networks

  • Access to remote resources

    • File downloads

  • Data Backups

    • Shared storage device

    • Regular data backup

  • Greater performance

    • Distributed computing


Types of computer networks according to the distance between nodes

Types of Computer Networksaccording to the distance between nodes

  • LAN: Local Area Network

  • WAN: Wide Area Network


Information and communication technology fundamentals

LAN

  • A network of computers located in the same building or a handful of nearby buildings

  • Examples:

    • Computer network at SEECS

    • Computer network of a University campus


Information and communication technology fundamentals

WAN

  • A network in which computers are separated by great distances, typically across cities or even continents

  • May consist of several interconnected LANs

  • Example:

    • The network connecting the ATM of a bank located in various cities

    • A network connecting the local and oversea offices of a SW house

    • Internet


Hybrid networks

Hybrid Networks

  • Metropolitan Area Networks

  • Campus Area Networks

  • Home Area Networks

  • Personal Area Networks


Information and communication technology fundamentals

Classification

(Geographical Scope)

  • Wide Area Networks

  • Metropolitan Area Networks

  • Campus Area Networks

  • Local Area Networks

  • Home Area Networks

  • Personal Area Networks

Decreasing

Scope


Software part of a network

Software part of a Network

  • Application

    • Email

    • Browsing

    • Conferencing

    • Chatting (text/voice)

    • File Transfer

    • Audio/Video Streaming


Software part of a network1

Software part of a Network

  • Protocols

    • Language that a computer uses to achieve data communication

    • Set of Rules


Packet

Packet

  • The smallest unit of data transmitted over a computer network

  • A message to be transferred over the network is broken up into small packets by the sending computer


Packet1

Packet

  • Each packet consists of

    • Header part

      • Contains control info to assist in routing of the packet

      • Source address

      • Destination address

    • Payload part

      • Contains actual data

    • Error control part

Header

Payload

Error Control

Packet


Packet2

Packet

  • All packets travel independently

  • When all packets are received by the destination computer, it reassembles them to form the original message


Hardware part of a network

Hardware part of a network


Modem

Modem

  • Plain Old Telephone System (POTS)

    • Standard phone line

    • Two-way voice communication

    • Uses analog transmission techniques

    • Data communication is slow


Modem1

Modem

  • Modem

    • Modulator/DEModulator

    • Computer sends data in digital form

    • Modem provides a hardware interface between computer and telephone lines

    • Transmission speed upto 56Kbps

    • V.92 is the current modem standard

    • Several modem types

      • Internal

      • External

      • Voice

      • Fax


Information and communication technology fundamentals

ISDN

  • Integrated Services Digital Network

  • Basic rate uses three channels

    • Basic Rate Interface (BRI)

    • Two data channels each support 64 Kbps

    • Control channel 16kbps

  • Primary rate uses 24/32 channels

    • Primary Rate Interface (PRI)

    • U.S standard: 23 data channels each supporting 64 kbps, 1 control channel at 64 kbps

    • Europe standard: 30 data channels each supporting 64 kbps, 2 control channel at 64 kbps

  • ISDN adapter required at computer


Information and communication technology fundamentals

ISDN


Information and communication technology fundamentals

DSL

  • Digital Subscriber Line (DSL) Modem

    • Newer technology to provide better data rates over the telephone lines

    • Several versions exist

      • Different transfer rates for different version

      • Asymmetrical DSL (ADSL)

        • Upload speed slower than download speed

      • Symmetrical DSL (SDSL)

    • 100 Kbps to 30 Mbps


Lan card

LAN Card

  • Network Interface Card (NIC)

    • LAN card

    • Digital Interface + Protocol

    • Provides higher data rates


Information and communication technology fundamentals

ATM

  • ATM

    • Asynchronous Transfer Mode

    • Efficient transfer of video and sound

      • Real Time traffic

    • Requires a special NIC and hardware


Wireless lan card

Wireless LAN Card

  • Wireless NIC

    • Transmission over air is not digital

    • Provides Interface + Protocol

    • IEEE 802.11

      • Also called Wi-Fi

      • Institute of Electronic and Electrical Engineers

    • Several versions

      • 802.11b connects up to 11Mbps

      • 802.11g connects up to 56Mbps

      • 802.11n connects up to 600Mbps


Wlan card

WLAN Card


Where is all this hardware located

Where is all this hardware located?


How can we connect these computers

Now that we have some software and hardware on each computer..

How can we connect these computers?


Network topologies

Network Topologies

  • Topology

    • Logical layout of wires and equipment

    • Choice affects

      • Network performance

      • Network size

      • Network collision detection

    • Several different types


Point to point p2p

Point-to-Point (P2P)

Computer

A

Computer

B


Information and communication technology fundamentals

P2P

  • Inexpensive

  • Limited connectivity

  • Quite often used for connecting two LANs to form a WAN


Network topologies1

Network Topologies

  • Bus topology

    • Also called linear bus

    • One wire connects all nodes

    • Terminator ends the wires

    • Advantages

      • Easy to setup

      • Small amount of wire

    • Disadvantages

      • Slow

      • Easy to crash


Network topologies2

Network Topologies

  • Star topology

    • All nodes connect to a single device e.g. hub

      • Packets sent to hub

      • Hub sends packet to destination

    • Advantages

      • Easy to setup

      • One cable can not crash network

    • Disadvantages

      • One hub crashing downs entire network

      • Uses lots of cable

    • Most common topology


Network topologies3

Network Topologies


Network topology

Network Topology

  • Ring topology

    • Nodes connected in a circle

    • Tokens used to transmit data

      • Nodes must wait for token to send

    • Advantages

      • Time to send data is known

      • No data collisions

    • Disadvantages

      • Slow

      • Lots of cable


Network topology1

Network Topology

  • Mesh topology

    • All computers connected together

    • Internet is a mesh network

    • Advantage

      • Data will always be delivered

    • Disadvantages

      • Lots of cable

      • Hard to setup


Network topology2

Network Topology


Linking hardware

Linking Hardware

Computer

E

Computer

A

Computer

D

Linking Hardware

Computer

B

Computer

C


Types of linking hardware

Types of Linking Hardware

  • Hubs

  • Bridges

  • Switches

  • Routers

  • Gateways


Information and communication technology fundamentals

Hub

  • A device that is used to connect several computers to form a network

  • A hub has several ports. The number generally is 8, 12, 16, 24, 32, or 48

  • Most dumb among all linking devices


Information and communication technology fundamentals

Hub

  • Each computer in a network is connected to one of those ports through a cable

  • A computer wanting to send a message to one of the others in the network sends a message to the hub, which, in turn, broadcasts the message to all others connected to it


Bridge

Bridge

  • Used to form a connection between two separate, but similar networks

  • In a way, it creates an extended LAN by passing information between two or more LANs

  • Packets sent to remote LAN cross

    • Other packets do not cross


Switch

Switch

  • Has multiple ports

  • Learns which machine is connected to which port

  • Only intended node receives transmission

  • Reduces broadcast traffic


Router

Router

  • Connects two or more LANs together

  • Packets sent to remote LAN cross

  • Network is segmented by IP address

  • Connect internal networks to the Internet

  • Need configured before installation


Router1

Router

  • Examines the destination info in each arriving packet

    • Routes it through the most efficient path available

  • Either delivers the packet to the destination computer across a local network

  • OR forwards the packet to another router that is closer to the final destination


Gateway

Gateway

  • A special-purpose computer that connects and translates between networks that use different communications protocols

  • LAN’s may use a gateway (or router) to connect to the Internet


Network media

How to Connect?

Network Media


Network media1

Network Media

  • Links that connect nodes

  • Choice impacts

    • Speed

    • Security

    • Size


Wire based media

Wire Based Media

Twisted-pair cabling

Most common LAN cable

Called Cat5 or 100BaseT

Four pairs of copper cable twisted

May be shielded from interference

Speeds range from 1 Mbps to 1,000 Mbps


Wire based media1

Wire Based Media

  • Coaxial cable

    • Similar to cable TV wire

    • One wire runs through cable

    • Shielded from interference

    • Speeds up to 10 Mbps

    • Nearly obsolete


Wire based media2

Wire Based Media

Fiber-optic cable

Data is transmitted with light pulses

Glass strand instead of cable

Immune to interference

Very secure

Hard to work with

Speeds up to 100 Gbps


Wireless media

Wireless Media

  • Data transmitted through the air

  • LANs use radio waves

  • WANs use microwave signals

  • Easy to setup

  • Difficult to secure


End of lecture

END of LECTURE


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