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Unformatted text preview: 1 Computer Networks CSci232: Introduction 1 Introduction to Networking What is a (computer/data) network? Statistical multiplexing Packet switching OSI Model and Internet Architecture Introduction to the Internet Readings Chapter 1 Computer Networks CSci232: Introduction 2 What is a Network? There are many 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 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 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 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 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 2 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 one circuit original telephone network Analogy: railroads and trains Packet Switching divide information into small chunks (packets) each packet delivered independently store-and-forward packets Internet (also Postal Service, but they dont tear your mail into pieces first!) Analogy: highways and cars Computer Networks CSci232: Introduction 8 Common Circuit Switching Methods Sharing of network resources among multiple users Common multiplexing strategies for circuit switching...
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