computer networks layers
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© Oxford University Press 2011
Computer NetworksComputer Networks
Bhushan Trivedi, Director, MCA Programme, at the GLS Institute of
Computer Technology, Ahmadabad
© Oxford University Press 2011
Chapter 1Chapter 1Introduction to computer Introduction to computer
networksnetworks
© 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
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Advantages of layers
• Reducing the complexity• Division of Work• Standard Interfacing between Components• Replacing a component is easy• Independence in Protocol design
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Disadvantages of layers
• Reduced Speed and Performance• Increased Memory usage• Sensor Networks Node
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Layers for OSI and TCP/IP
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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
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Example CO vs CL
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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,
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The Physical Layer
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The Data Link Layer
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The Network Layer
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Network Layer Functioning
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Routing at Network Layer
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Extracting Prefix
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Routing between different networks
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Transport layer and reliability by retransmitting
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Application Layer
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Other
• Distributed Systems– WWW
• Peer to peer networks• Client server networks
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X.25
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DTE routing
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