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Computer NetworksCSC524
Lecture 1Dr. Mohsin Iftikhar
Office: 4675636Cell: 0543-795 002
[email protected]@gmail.com
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar
Introduction
• Text Book:– Computer Networks and Internets
Douglas E. Comer (5th Edition)• Reference Books– Computer NetworksAndrew 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-ApplicationLayer 6-PresentationLayer 5-SessionLayer 4-TransportLayer 3-NetworkLayer 2-Data LinkLayer 1-Physical
Lecture 1: Introduction (CSC524) : Dr. Mohsin Iftikhar
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.
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
