What's the Internet:"nuts and bolts'"view俱体细 millions of connected X router 必 computing devices:hosts workstation end systems 目server mobile □running network apps cal ISP ▣communication links fiber,copper,radio, satellite transmission rate bandwidth routers:forward packets (chunks(大块)of data) compary边 network Introduction 1-4Introduction 1-4 What’s the Internet: “nuts and bolts” view (具体细节) ❑ millions of connected computing devices: hosts = end systems ❑ running network apps ❑ communication links ❖ fiber, copper, radio, satellite ❖ transmission rate = bandwidth ❑ routers: forward packets (chunks（大块） of data) local ISP company network regional ISP router workstation server mobile