CHAPTER 9 COMMUNICATIONS AND NETWORKS

Communications is the process of sharing data, programs, and information between two or more computers. Applications include e-mail, instant messaging, Internet telephones, and electronic commerce.

COMMUNICATION SYSTEMS = transmit data from one location to another.

• sending and receiving devices
• communication channels ( transmission medium)
• connection (communication) devices
• data transmission specifications

COMMUNICATION CHANNELS carry data from one computer to another.

PHYSICAL CONNECTIONS

• twisted pair (telephones lines and Ethernet cables)
• coaxial cable
• fiber-optic cable

WIRELESS CONNECTIONS

• infrared
• radio frequency (RF)
• microwave
• satellite

CONNECTION DEVICES

1. modem

• telephone
• DSL
• cable
• wireless

2. connection services

• dial-up
• DSL(digital subscriber line)
• ADSL
• cable
• satellite/air
• cellular services (3G cellular networks)

NETWORK TYPE

• Local area networks ( LANs )
• Home networks
• Wireless LANs (WLANs)
• Personal area networks (PANs)
• Metropolitan area networks (MANs）
• Wide area networks (WANs）

NETWORK ARCHITECTURE describes how a computer network is configured and what strategies are employed.

TOPOLOGIES

• bus
• ring
• star
• tree
• hybrid
• mesh

STRATEGIES

• terminal
• client/server
• peer-to-peer

ORGANIZATIONAL INTERNET

• intranets
• extranets