2. “I think there is a world of market for maybe five computers” Thomas J. Watson Chairman IBM, 1943
3. Why Use Networks? Network Group of computers and devices Connected by transmission media Stand-alone computer Not connected to other computers Uses local software and data Advantages of networks over standalone computers Device sharing by multiple users Saves money and time Central network management
29. Impact of Data Communications It links business processes performed by independent computer systems to improve organizational efficiency and effectiveness It links a business to its customers Communication devices, such as cell phones, personal digital assistants, etc.
30. Local Area Network LAN is linkage of computers in a specific geographical area (usually within an office or building) such as in hotels, restaurants, or country clubs using transmission medium such as twisted pair wire or coaxial cable.
31. Why Local Area Network (LAN)? Increased processing and transfer requirements in many graphics-intensive applications now require significantly higher transfer rates (data, audio, image, video) Decreased cost of storage space leads to program and file bloat, increased need for transfer capacity Watch this video
34. Full versus half duplex Half duplex: communication can happen in both directions but one at a time (like walkie-talkie) Full duplex: communication can happen in both directions at the same time (like a phone)
35. Client Is any network entity that can request resources from the network. Workstations can be clients but not all clients are workstations For example, a printer can request resources from the network, it is a client, not a workstation.
36. Server A computer that provides resources to the clients on the network. Servers are typically powerful computers
38. Hub vs. Switch Hub—sends signals to all computers connected Switch– sends signals to intended computer(s)
39. LANs share Files (databases) Resources (Printers, fax) Programs (Fidelio, MS Office) Working together Communication
40. WAN (Wide Area Network ) Communications Hardware WAN=Connection of at least two LANs Down-line processor/ Multiplexer Front-end Processor PBX(Private Branch Exchange) Watch Video
70. Server Types File Server: holds and distributes files Print Server: handles printing jobs from clients Proxy Server: performs a function on behalf of other computers Application Server: hosts a network application (i.e. Marriott’s central reservation system, Marsha) Web Server: handles web pages and other web content (i.e. Marriott.com, Hilton.com, Starwood.com) Mail Server: hosts and delivers electronic mail. Fax Server: sends and receives faxes electronically. Voice over IP Server: Handles calls on Internet Protocol
71. Physical Media Coaxial Cable Thinnet (BNC Connector and RG-58) Twisted Pair Cable Category 1 – Category 6 RJ-11 and RJ-45 Connectors Fiber Optic Cable
72. Coaxial Cable Contains a center conductor, made of copper, surrounded by a plastic jacket Teflon type covering plenum-rated coating does not burn easily Coax is not used in LANs today but still used widely by TV cable operators
76. Connectors With thinnet, you use BNC (BayoNet Connector) connectors to attach stations to the network. BNC Connector locks securely with a quarter-twist motion A T-connector is used to connect backbone devices
80. Twisted-pair cable Consists of multiple, individually insulated wires that are twisted together in pairs Sometimes a metallic shield is placed around pairs shielded twisted pair (STP) Unshielded twisted pair (UTP)
81. Why twisted? Electromagnetic signals create interference crosstalk Twisting the cables in pairs reduce intereference Most common cable
83. Fiber Optic Cable A glass or plastic fiber that carries light along its length. This cable is the fastest and most expensive transmission medium in the world today
93. Network Topologies The manner in which workstations are connected together physically and logically is referred to as a NETWORK TOPOLOGY. 4 Types: Bus (Video) Ring (Video) Star (Video) Hybrid
102. Why Hybrid (Tiered)? Reliability—less service interruption Capacity- not easily saturated Cost – low cost networks can build up Needs- not every department need the same equipment (accounting vs. graphics)
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105. The five basic functions of network management are:Fault management Configuration management Performance management Security Management Accounting Management