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Network Overview Network Operating Systems What is a Network? • Network - definition Group of interconnected computers (devices) sharing services, resources and a common communications link. • So, what does that mean? • Computers / Devices Workstations (uses resources from server) Servers (provides resources and/or security) Communication Devices - Routers, Hubs, Modems, etc. (gets data from “here to there”) Service Devices - Printers, Fax, CD Towers, Tape Backup, etc. What is a Network (cont.) • Services E-mail Time management - Daytimer, Room Schedules Video / Telephone Conferencing • Resources Disk Space Large Files (Databases, Graphics, etc.) Costly devices - Color Laser Printers, etc. Applications What is a Network (cont.) • Common Communications Link Wire based cable – STP, UTP, Coax Fiber optic Wireless - Radio, IR, Microwave, etc. • Types of Networks Centralized Decentralized Collaborative or Cooperative Types of Networks • Centralized One central computer did all of the processing User interacts at the system console or remote terminal. Example - Mainframe systems • Distributed (Decentralized) PCs can process and store data at the users desk Customize each PC for the user Free up time on the “Big Boxes” for larger tasks Types of Networks (cont.) • Collaborative / Cooperative Share processing power between devices One system may run processes on another systems CPU. Some processes may be designed to run on more than one system at the same time. Network Models • Peer-to-Peer Every computer is a workstation Every computer may be a server User is responsible for administering the shared resources on their system (“distributed” or “workgroup” administration) Very cost efficient for small companies or offices with limited resources and where security is not a big factor on the network Network Models (cont.) • Client / Server “Dedicated” servers provide resources and security Servers provide a single place for security and resource management Workstations utilize these resources within the security structure Workstations can have minimal configurations therefore holding system cost down Network Shapes and Sizes • LAN - Local Area Network Within the “4 walls” of a building or campus Shorter transmission distance usually means higher speed Typically wire or fiber optic medium Less expensive technology Relatively error free and “no cost” transmission Shapes and Sizes (cont.) • MAN - Metropolitan Area Network Interconnect multiple LANs within the “city” limits Maintains high speed transmission Moderately expensive technology Relatively error free and “low cost” transmission Shapes and Sizes (cont.) • WAN - Wide Area Network Interconnect multiple LANs and MANs Unlimited geographical area (anywhere in the world) Transmission speed and cost VERY dependent on technology Much more sophisticated and complex than LANs or MANs More susceptible to errors due to transmission distance and media
"Network Overview (PowerPoint)"