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Information and Communication Technology Fundamentals

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Title: Slide 1 Author: ayesha Last modified by: ayesha Created Date: 11/19/2008 8:24:33 AM Document presentation format: On-screen Show (4:3) Other titles – PowerPoint PPT presentation

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Title: Information and Communication Technology Fundamentals


1
Information and Communication Technology
Fundamentals
  • Credits Hours 21

Instructor Ayesha Bint Saleem
2
Highlights of last lecture
3
3 aspects of a network
  • Software
  • Hardware
  • Medium

4
Software
  • Application
  • Protocols
  • Packet
  • Payload (Data part)
  • Header (Control information part)

5
Hardware
  • Modem
  • ISDN
  • DSL
  • LAN Card
  • Wireless LAN Card
  • ATM
  • Wimax

6
Medium
  • Wired
  • Twisted pair cable
  • Co-axial cable
  • Fiber optic cable
  • Wireless

7
Network Topologies
  • Point 2 Point
  • Bus
  • Ring
  • Mesh
  • Star

8
Network Linking Devices
  • Hub
  • Bridge
  • Switch
  • Router
  • Gateway

9
Classification of Networks according to
geographical scope
  • Wide Area Networks
  • Metropolitan Area Networks
  • Campus Area Networks
  • Local Area Networks
  • Home Area Networks
  • Personal Area Networks

Decreasing Scope
10
NETWORKS - Ii
11
Presentation Credits
  • Data Communications and Networking, Behrouz A.
    Forouzan
  • Computer Networks, Tanenbaum
  • Dr Junaid, EE Dept, SEECS

12
Types of communication
  • According to data direction
  • Simplex
  • One-way communication (only send or only receive)
  • Half-Duplex
  • Two-way communication (send/receive) but one at a
    time
  • Full Duplex
  • Two-way communication (send/receive) at the same
    time

13
Types of communication
  • According to intended recipients
  • Unicast
  • Sending data to only one recipient
  • Multicast
  • Sending data to multiple recipients
  • Possibly at different locations
  • Broadcast
  • Sending data to everybody

14
  • You open a browser e.g. Internet Explorer
  • Type address on the browsers address bar

15
Networking SOFTWARE
16
Example application
http//www.niit.edu.pk
17
  • The SEECS page is displayed in front of you after
    some time

18
(No Transcript)
19
  • A lot of things are happening from your typing
    the address to getting to see the SEECS home page
  • Inside your computer
  • AND
  • On the network

20
  • Like
  • Locating where the SEECS server is located which
    is hosting the SEECS website
  • Establishing a connection with the SEECS server
  • Requesting server to send you the webpage
  • Receiving data from server in the form of packets
  • Ensuring packets arriving are free of error
  • Arranging packets in order to re-create the
    original webpage

21
  • Who is dealing-with/enabling all this?
  • Network software on your computer
  • Network software on the NIIT server
  • Network software on many other devices that you
    are not aware of
  • DNS Server
  • Router
  • Possibly many others

22
  • Network software follows different procedures to
    have the web-page displayed to you
  • These procedures are called protocols
  • Variety of protocols are running on your computer
  • Each responsible to perform a different task

23
  • To reduce design complexity, the functions that a
    network software provides are organized as a
    stack of levels or layers
  • Each layer uses the services of the layer below
    it
  • Each layer offers some services to the layer
    above it

24
  • The concept of layering is used in daily life

25
Two friends communicating through postal mail
Letter is written, put in an envelope, and
dropped in mailbox
Letter is picked up removed from the envelope and
read
Higher Layers
The letter is carried from the mailbox to a post
office
The letter is carried from the post office to the
mailbox
Middle Layers
The letter is delivered to a carrier by the post
office
The letter is delivered to from the carrier to
the post office
Lower Layers
Parcel is carried from the source to destination
26
Internet Model
  • The layering structure that internet uses
  • Consists of five layers

27
Internet TCP/IP Model
Application Layer
Transport Layer
TCP
Network Layer
IP
Data Link Layer
Physical Layer
28
  • Physical Layer
  • Responsible for transmitting raw bits over a
    communication medium (channel)
  • Data Link Layer
  • Source DLL gives a packet to the physical layer
    in the form of bits
  • Destination DLL receives bits of the packet from
    the physical layer
  • Node to node delivery of a packet
  • Error control
  • Use of Acknowledgements

29
  • Network Layer
  • End to-end delivery of a packet
  • Transport Layer
  • Process to process delivery of a packet
  • May include error control
  • Application layer
  • Enable use of network
  • Provides Interface

30
Addressing in the Internet
  • Each station must be addressable
  • Two kinds of addresses
  • 1) Physical addressing (MAC addresses)
  • 2) Logical addressing (IP addresses)

31
Addressing in the Internet
  • The communicating applications (source/
    destination applications) must also be
    identifiable
  • Identified through TCP ports
  • A socket (IP address TCP port) identifies both
    an application and the machine its on.

32
Physical Addressing MAC
MAC Address 48 bits (Ethernet) Flat
addressing Usually non-configurable
33
Logical Addressing IP
4,294,967,296 possible addresses 232
IP Version 4 Address 32 bits IP Version 6
Address 128 bits Hierarchical addressing 2
parts a network part and a host part. Machines
in a LAN have the same network part they differ
in host parts
34
Logical Addressing IP
How is the network part of an IP address defined
Subnet mask
35
IP (Internet Protocol)
IP Address 192.168.15.2 (decimal) 11000000   101
01000   00001111   00000010 (binary) Subnet
Mask 255.255.255.0 (decimal) 11111111   1111111
1   11111111   00000000 (binary)
IP Address 192.168.15.2 (decimal) 11000000   101
01000   00001111   00000010 (binary) Subnet
Mask 255.255.255.0 (decimal) 11111111   1111111
1   11111111   00000000 (binary)

Network part Host part
36
Applications Identification
How to identify source/ destination application
communicating The source/ destination
applications are identified through TCP
ports Common TCP Ports HTTP 80 SMTP25
DNS 53
37
Naming
Machine addresses are difficult to
memorize Solution Provide recognizable names to
numerically addressed Internet resources.
Examples
google.com stanford.edu niit.edu.pk
google.com stanford.edu niit.edu.pk
38
Naming
How to manage address to name mapping?
  • A hosts file on each machine
  • Unix/ Linux /etc/hosts file
  • Windows SystemRoot\system32\drivers\etc
  • A decentralized domain name server system
  • Scalable solution
  • The name to IP mapping is available at a DNS
    server

39
Example application (contd.)
40
DNS Client/Server Exchange
Request
41
DNS Client/Server Exchange
Reply
42
ARP Client/Server Exchange
Request
Request
43
ARP Client/Server Exchange
Reply
44
HTTP Client/Server Exchange
Request
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