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414Lecture2preview - Lecture 2 Overview Circuit vs. Packet...

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Lecture 2 – Overview Circuit vs. Packet Switching, Delay, Loss, and Throughput ECSE 414 – Fall 2009
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 2 Today’s Outline Last time: Internet architecture overview Edge, access network, core Tier-1, 2, 3 ISPs Circuit-switching vs. packet-switching Delay, loss, and throughput
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 3 Network Architecture and Switching Question to consider: What are the differences between the Internet and telephone networks?
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 4 The Railroad Network Railroad used as a model for phone net Centralized network Network components connected to a centralized point that handles switching and routing Customer loses some control Possible congestion at hubs
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 5 The Early Telephone network Users all connect to the “central office” where calls are switched
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 6 A closer look at network structure: network edge: applications and hosts access networks, physical media: wired, wireless communication links first/last mile network core: interconnected routers network of networks
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 7 The Network Core Fundamental question: how is data transferred through net? circuit switching: dedicated circuit per call: telephone net packet-switching: data sent thru net in discrete “chunks”
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 8 Circuit Switching End-end resources reserved for “call” Example: Telephone network call setup required dedicated resources: no sharing link bandwidth, switch capacity circuit-like (guaranteed) performance
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 9 Circuit-Switched Networks Network resources divided into fixed “pieces” (e.g., chunks of time, bandwidth) Pieces allocated to calls as requested Need to reserve resources before using them (+) Guaranteed level of service for duration of call (-) Resource goes idle if not used by owning call (no sharing)
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 10 Packet Switching Data stream divided into packets Each packet transmitted independently Resources used as needed Statistical multiplexing Resource contention No resource reservation No call setup No guaranteed service
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Michael Rabbat, Fall 2010 ECSE 414, Lecture 2 11 Sharing Resources: FDM and TDM Frequency Division Multiplexing (FDM) frequency time Time Division Multiplexing (TDM) frequency time 4 “resources”
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414Lecture2preview - Lecture 2 Overview Circuit vs. Packet...

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