Transcript Document
Chapter 9 Communications and Networks Competencies (Page 1 of 2) Discuss connectivity, the wireless revolution, and communication systems Describe physical and wireless communications channels Discuss connection devices, including modems, T1, DSL, cable modem, and satellite connections Describe data transmission factors, including bandwidths and protocols Discuss network and key network terminology Page 238 CE06_PP09-2 Competencies (Page 2 of 2) Describe different types of networks, including local area, metropolitan area, and wide area networks Describe network architectures, including configurations and strategies Describe organizational uses of Internet technologies, including intranets, extranets, and firewalls Page 238 CE06_PP09-3 Communications The process of sharing data, programs, and information between two or more computers Page 240 CE06_PP09-4 Communication Systems Four basic elements Sending and receiving devices Communication channel Connection devices Data transmission specifications Page 241 CE06_PP09-5 Communication Channels Channels carry data from one computer to another Two categories of communication channels Physical connection Wireless connection Page 242 CE06_PP09-6 Physical Connections Telephone lines Coaxial cable Fiber-optic cable Return Page 242 CE06_PP09-7 Wireless Connections Infrared, Broadcast Radio, Microwave Infrared Broadcast radio Wi-FI (wireless fidelity)/802.11 Microwave Stations Bluetooth Satellite GPS Page 242 Microwave dish CE06_PP09-8 Connection Device Signals Types of signals Analog Digital Page 244 CE06_PP09-9 Connection Device Types Types of modems External Internal PC Card Wireless Page 244 CE06_PP09-10 Connection Services Dial-Up services Leased lines – T1, T2, T3 and T4 Digital subscriber line (DSL) Uses existing phone lines One type widely used is ADSL Cable modems Uses existing TV cable Provides speeds as fast as DSL at a lower cost Satellite/air connection services Seven times faster than dial-up Slower than DSL & cable modem Page 245 CE06_PP09-11 Typical User Connection Costs & Speeds Type Fee Speed Seconds to Get Images Dial-up $16 56 kbps 45.0 DSL 50 1.5 mbps 1.7 Cable Modem 40 1.5 mbps 1.7 Satellite 60 900 kbps 2.8 Page 245 CE06_PP09-12 Bandwidth Measurement of the capacity of the channel Categories Low bandwidths or Voiceband Medium band Broadband Used for high capacity transmission Used by DSL, cable, and satellite Page 246 CE06_PP09-13 Protocols Set of communication rules Standard for Internet: TCP/IP (Transmission control protocol/Internet protocol) Identifies devices Reformats information Page 247 CE06_PP09-14 Networks A computer network is a communication system Connects two or more computers Allows information exchange Page 247 CE06_PP09-15 Network Types A local area network (LAN): computers are physically close to each other, usually in the same building Metropolitan area network (MAN) links two or more LANs within a city A wide area network (WAN) extends over a long distance Page 249 Each network site is a node on the network Data transmitted over common pathways called a backbone CE06_PP09-16 Internets and Extranets Intranets Private network within an organization Provides information to employees Extranets Private network that connects organizations Used to allow suppliers and others access Firewalls Security system Protects against external threats Page 257 CE06_PP09-17