9/26/2011 - - PDF document

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Introduction 1-4

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Hi Hi

Got the time?

2:00

TCP connection response Get http://www.awl.com/kurose-ross

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time

Introduction 1-5

TCP connection request

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Network Services Application Services Communication Service Network Services Application Services Communication Service

Web Server Web Client Application logic Reliable delivery Transfer “bits”

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Web Server Web Client Application logic protocol Reliable delivery protocol Transfer “bits” protocol

Network Services Application Services Communication Service Network Services Application Services Communication Service

Layer Interface Layer Interface

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Which is the best? … It depends on (i) what it is used for, and (ii) what it is built ontop of

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application transport network link physical E.g., TCP (CO) UDP (CL) E.g., IP (CL) E.g., Ethernet (CL) ATM (CO) Two notes on the physical layer:

• Guided (e.g., coaxial cable, fiber, etc) vs.

unguided (satellite, wireless, etc.)

• Signaling, modulation, encoding, etc,

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