Computer Networks
CSC524
Lecture 1
Dr. Mohsin Iftikhar
Office: 4675636
Cell: 0543-795 002
miftikhar@ksu.edu.sa
mohsinunsw@gmail.com
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar
Introduction
• Text Book:
– Computer Networks and Internets
Douglas E. Comer (5th Edition)
• Reference Books
– Computer Networks
Andrew S. Tanenbaum (4th Edition)
– CCNA ICND 1 Official Exam Certification Guide
– CCNA ICND 2 Official Exam Certification Guide
by Wendell Odom
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar
Introduction
• Background of Networking
• How Computer Networking Started
• Key Aspects of Networking
– Network Applications and Network Programming
– Data Communications
– Packet Switching and Networking Technologies
– Internetworking with TCP/IP
– Additional Networking Concepts and Technologies
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar
ISO and OSI Seven Layer Reference
Model
• International Standard Organization (ISO)
– Seven Layers Model
Layer 7-Application
Layer 6-Presentation
Layer 5-Session
Layer 4-Transport
Layer 3-Network
Layer 2-Data Link
Layer 1-Physical
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar
Application Layer
• Application layer is the top layer of OSI model
which provides different kinds of services to
the end-user. For example, HTTP, Telnet, FTP,
SMTP are the examples of different kinds of
applications.
Lecture 1: Introduction (CSC524) : Dr.
Mohsin Iftikhar
Presentation Layer
• Presentation layer is concerned with the data
format. Whenever a user uses an application
service being provided by the application
layer, application layer passes that data
written by human language to the
presentation layer, presentation layer converts
that data from human language to machine
language (0,1) at the sending machine side
and vice versa on the receiving side.
Lecture 1: Introduction (CSC524) : Dr.
Mohsin Iftikhar
Session Layer
• Session Layer is responsible for three things, it
initiates the session, maintains the session
during data transfer and terminates the
session when the data transfer is completed.
Lecture 1: Introduction (CSC524) : Dr.
Mohsin Iftikhar
Transport Layer
• This layer performs a number of tasks
– Segmentation and reassembly
– Reliability through acknowledgements
– Error Recovery
– Flow Control through windowing
– Sequencing
Lecture 1: Introduction (CSC524) : Dr.
Mohsin Iftikhar
Network Layer
• This layer provides routing. Router works on
network layer. This layer is responsible for
defining the end-to-end, easiest shortest
possible route from source to destination.
Lecture 1: Introduction (CSC524) : Dr.
Mohsin Iftikhar
Data Link Layer
• This is the only layer, which attach header and
trailer both with the data and data becomes
frame at this particular layer. This layer
provides error detection through Frame Check
Sequence (FCS). This layer can not provide
error recovery
Lecture 1: Introduction (CSC524) : Dr.
Mohsin Iftikhar
Physical Layer
• Physical layer is just concerned with the
physical characteristics. For example, what
type of cable to use, which pins will be used
for sending the data, which pins will be used
to receive the data etc.
Lecture 1: Introduction (CSC524) : Dr.
Mohsin Iftikhar
How Data Passes Through Layers
• Concept of Headers and Layers
– When data comes down through the layers, each layer attach a
header with it and this process is called encapsulation and on
the receiving side, each layer de attach the corresponding
header, which is called de-encapsulation.
• Concept of Protocol
– Protocol is a set of rules and regulations between corresponding
layers on different machines to govern the communication.
• Concept of Interface
– Interface is always between adjacent layers on the same
machine
• Major difference between protocol and Interface
– Protocol is always between layers of different machines and
interface is always between layers of same machine.
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar
TCP/IP Model
• Five Layer model: Transmission Control Protocol/Internet
Protocol (TCP/IP)
–
–
–
–
–
Application
Transport
Internet
Network Interface
Physical
• Application layer of TCP/IP is corresponding to top three
layers of OSI (application, presentation and session),
Transport is equal to transport, Internet is corresponding to
network, network interface is equal to data link and
physical layer is equal to physical layer of OSI model.
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar
Some More Concepts
• Encapsulation
• De-encapsulation
• Different types of Applications at different
layers
• Examples of application, transport and
internet layer
• Questions
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar