Introduction - I ntroduction to Ne tworking pute twork What is a(com r\/data ne tatistical m ultiple xing S t Packe switching I l rne cture OS Mode and I

Introduction - I ntroduction to Ne tworking pute twork What...

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Computer Networks CSci232: Introduction 1 Introduction to Networking What is a (computer/data) network? Statistical multiplexingPacket switchingOSI Model and Internet ArchitectureIntroduction to theInternet Readings Chapter 1
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Computer Networks CSci232: Introduction 2 What is a Network? Therearemany types of networks! Transportation Networks Transport goods using trucks, ships, airplanes, … Postal Services Delivering letters, parcels, etc. Broadcast and cable TV networks Telephone networks Internet “Social/Human networks”
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Computer Networks CSci232: Introduction 3 Key Features of Networks Providing certain services transport goods, mail, information or data Shared resources used by many users, often concurrently Basic building blocks nodes (active entities): process and transfer goods/data links (passive medium): passive “carrier” of goods/data Typically “multi-hop” two “end points” cannot directly reach each other need other nodes/entities to relay
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Computer Networks CSci232: Introduction 4 Data/Computer Networks Delivery of information (“data”) among computers of all kinds servers, desktops, laptop, PDAs, cell phones, ...... General-Purpose Not for specific types of data or groups of nodes, or using specific technologies Utilizing a variety of technologies “physical/link layer” technologies for connecting nodes copper wires, optical links, wireless radio, satellite or even “non-electronic” means: e.g., cars, postal services, humans -- e.g., recent “delay-tolerant networks” efforts for 3 rd world countries
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Computer Networks CSci232: Introduction 5 How to Build Data/Computer Networks Two possibilities infrastructure-less (ad hoc, peer-to-peer) (end) nodes also help other (end) nodes, i.e., peers, to relay data infrastructure-based use special nodes (switches, routers, gateways) to help relay data
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Computer Networks CSci232: Introduction 6 Connectivity and Inter-networking Point-to-point vs. broadcast links/ wireless media switched networks connecting “clouds” (existing physical networks) inter-networking using gateways, virtual tunnels, overlays (a) (b) base station
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Computer Networks CSci232: Introduction 7 Resource Sharing in Switched Networks Multiplexing Strategies Circuit Switching set up a dedicated route (“circuit”) first carry all bits of a “conversation” on onecircuit original telephone network Analogy: railroads and trains Packet Switching divideinformation into small chunks (“packets”) each packet delivered independently “store-and-forward” packets Internet (also Postal Service, but they don’t tear your mail into pieces first!) Analogy: highways and cars
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Computer Networks CSci232: Introduction 8 Common Circuit Switching Methods Sharing of network resources among multiple users Common multiplexing strategies for circuit switching Time Division Multiplexing Access (TDMA) Frequency Division Multiplexing Access (FDMA) Code Division Multiplexing Access (CDMA) What happens if running out of circuits?
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