全套英文版《计算机网络》PPT电子课件教案-Part I Introduction.pptVIP

Part I: Introduction Chapter goal: get context, overview, “feel” of networking more depth, detail later in course approach: descriptive use Internet as example Overview: what’s the Internet what’s a protocol? network edge network core access net, physical media performance: loss, delay protocol layers, service models backbones, NAPs, ISPs history ATM network What’s the Internet: “nuts and bolts” view millions of connected computing devices: hosts, end-systems pc’s workstations, servers PDA’s phones, toasters running network apps communication links fiber, copper, radio, satellite routers: forward packets (chunks) of data thru network What’s the Internet: “nuts and bolts” view protocols: control sending, receiving of msgs e.g., TCP, IP, HTTP, FTP, PPP Internet: “network of networks” loosely hierarchical public Internet versus private intranet Internet standards RFC: Request for comments IETF: Internet Engineering Task Force What’s the Internet: a service view communication infrastructure enables distributed applications: WWW, email, games, e-commerce, database., voting, more? communication services provided: connectionless connection-oriented cyberspace [Gibson]: “a consensual hallucination experienced daily by billions of operators, in every nation, .... What’s a protocol? human protocols: “what’s the time?” “I have a question” introductions … specific msgs sent … specific actions taken when msgs received, or other events network protocols: machines rather than humans all communication activity in Internet governed by protocols What’s a protocol? a human protocol and a computer network protocol: A closer look at network structure: network edge: applications and hosts network core: routers network of networks access networks, physical media: communication links The network edge: end systems (hosts): run application programs e.g., WWW, email at “edge of network” client/server model client host requests, receives service from server e.g., WWW client (browser)/