NETWORKING

NETWORKS TELECOMMUNICATIONS Two or more computers communicating Long distance communications

LAN Characteristics TOPOLOGY Bus Star Ring Protocol Polling CSMA/CD Token Ring

MAJOR FUNCTIONS Make long distance communication seem local Standardize network interface Standardize procedures for sending information Govern error transmission Govern security Govern integrity of data

NETWORK COMPONENTS Computers Media Software Network connections Satellites Microwave stations Multiplexer – combines many data streams into a single stream

Additional Media Type Electromagnetic waves A type of radio wave Used by satellites Used by portable computers

MICROWAVE STATIONS Needs a direct sight line SATELLITES

WAN TOPOLOGIES 1. Point to Point 2. Multidrop 3. Mesh 4. Star

Point to Point Direct Connection Between Computers

Advantage No Waiting Disadvantage Expensive to connect Adding new computer

Multidrop Hierarchical Between Concentrator

Advantage No Waiting Direct connections Disadvantage May find delays if going outside the predefined connections Adding new computer

Star Central Point Time Sharing Host

Advantage Centralized control (security) Disadvantage Centralized control (delays)

Mesh Individual Routes Needs a router

Advantage No Waiting Disadvantage Connections (solutions – servers)

Other types of NETWORKS Public access networks (government) VAN – value added network (extra feature – faxes) Private area networks (Sears) Public Data Network (TYMNET)

Wide Area Networks Environments

PSTN Public Switch Telephone Network

TYPES of Lines Private –Direct –Expensive Tie line –Dedicated without the use of the PSTN Exchanges –Foreign/private 800 numbers

DDN data digital network Only transmits DIGITAL information

PSN packet switching network Sends information in groups called PACKETS

ISDN integrated services digital network Sends only digital signals Transmits HIGH VOLUME of data Can use the Internet while using the phone line – use of two phone lines

DSL Digital Subscriber Line Translates digital signals to analog Transmits HIGHER VOLUME of data than ISDN Spreads analog signal over a wide range of frequencies