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Transcript
Computer Networks
Bhushan Trivedi, Director, MCA
Programme, at the GLS Institute of
Computer Technology, Ahmadabad
© Oxford University Press 2011
Chapter 1
Introduction to computer
networks
© Oxford University Press 2011
Questions to be answered
• How is a file downloaded
• How do emails reach their intended
recipients?
• How does a wired and a wireless connection
work the same?
• How is receipt of new data (for example a new
antivirus update), handled and by whom?
© Oxford University Press 2011
Layering Example
© Oxford University Press 2011
Advantages of layers
•
•
•
•
•
Reducing the complexity
Division of Work
Standard Interfacing between Components
Replacing a component is easy
Independence in Protocol design
© Oxford University Press 2011
Disadvantages of layers
• Reduced Speed and Performance
• Increased Memory usage
• Sensor Networks Node
© Oxford University Press 2011
Layers for OSI and TCP/IP
© Oxford University Press 2011
Connection Oriented vs
Connectionless
•
•
•
•
•
•
•
Connection establishment
Complete line occupied or not
Multiplexing
Robustness of the connection
Cost of the connection
Quality of service
Order of delivery
© Oxford University Press 2011
Example CO vs CL
© Oxford University Press 2011
OSI and TCP IP difference
• OSI has seven layers, TCP/IP has five layers.
• The OSI was connection-oriented, TCP/IP
model was connectionless
• The TCP/IP provided a choice (TCP or UDP) to
the customers.
• TCP/IP describes an existing set of protocols
The OSI model was more general
© Oxford University Press 2011
OSI and TCP IP difference
• OSI model distinguishes between an interface
and a protocol TCP IP does not
• The OSI model clearly mentions the physical
and data link layers.
• The Internet provides both, connection
oriented service over connectionless transfer
and connectionless service over
connectionless transfers,
© Oxford University Press 2011
The Physical Layer
© Oxford University Press 2011
The Data Link Layer
© Oxford University Press 2011
The Network Layer
© Oxford University Press 2011
Network Layer Functioning
© Oxford University Press 2011
Routing at Network Layer
© Oxford University Press 2011
Extracting Prefix
© Oxford University Press 2011
Routing between different networks
© Oxford University Press 2011
Transport layer and reliability by
retransmitting
© Oxford University Press 2011
Application Layer
© Oxford University Press 2011
Other
• Distributed Systems
– WWW
• Peer to peer networks
• Client server networks
© Oxford University Press 2011
X.25
© Oxford University Press 2011
DTE routing
© Oxford University Press 2011