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Evolution of Computing Networks: Managing Information Systems

Explore the evolution of computer networks from centralized to collaborative computing models. Understand network components and classifications, from LANs to WANs, and grasp networking fundamentals, services, and operating systems.

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Evolution of Computing Networks: Managing Information Systems

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  1. Technology Briefing Advanced Topics and Trends in Managing the Information Systems Infrastructure (telecommunication Network)

  2. Computer Networks • Network- A group of computer and associated peripheral devices connected by a communication channels capable of sharing data & other resources • Components: minimum 2 computers, telecommunication devices, communication channels, data & protocols • Evolution of network: Centralized, distributed & collaborative

  3. Centralized Computing • Period of 1940s – 1970s (mainframe era) • Central computer (mainframe) • Processing and storage of data • Terminal • Local input/output device • Not a true network – no information sharing

  4. Distributed Computing • Period of 1980s • Driver: Introduction of PCs • Organization can used multiple small computers to achieve many of same processing powers of a single mainframe • Separate computers work on subsets of tasks • Results are pooled via network

  5. Collaborative Computing • Period of 1990s • Synergistic form of distributed computing in which two or more networked computers are used to accomplish a common processing task. • Driver: PC become more powerful as mainframe of 70s

  6. Computing Networks Today • All types are still present (centralized, distributed, collaborative) • Usually combined into a network (Networks classified by size, distance covered and structure): • Local Area Network (LAN)- Private branch Exchange (PBX); Personal Area Network (PAN) • Wide area network (WAN)- Global Network; Enterprise Network; Value-Added Network (VAN); Metropolitan Area Network (MAN)

  7. Local Area Network • Covers a relatively small area, such as a building or floor • Computers share: Information and Peripheral devices • Usually one type of cable used • May includes a Wireless Local Area Network (WLAN)

  8. Private Branch Exchange (PBX) • Telephone system serving a particular location • Connects phones and computers • Connects PBX to outside network • Limited bandwidth because of limited phone line capacity

  9. Personal Area Networks • Exchange data between computing devices • Short range radio communication – 10 meters • E.g., networking of PCs, peripheral devices, mobile phones, portable stereos, etc. • Enabling Technology: Bluetooth

  10. Wide Area Network • Spans relatively large area. • Usually connects multiple LANs and have Different hardware and transmission media used • Used by multinational companies • Information transmitted across cities and countries • 4 specific types of WAN: a) Global networks: Span multiple countries. E.g., The Internet b) Enterprise networks: Connect disparate networks of a single organization c) Value-added networks (VAN): is Medium speed WANs, Third party managed and Shared by multiple organizations d) Metropolitan area networks (MAN): Limited geographic scope – usually a citywide area

  11. Networking Fundamentals • Three different roles: Servers, Clients & Peers • Server: Only provide services. Usually have: More advanced micro-processors; More memory. It allows many users to share services • Clients: computer that request services. Can be workstations, PCs, or Software applications. Usually one user per client. • Peer: May request and provide services. Usually use Peer-to-peer networks. Has Equivalent capabilities and responsibilities. Usually found in small offices and homes

  12. Network Services • (a) File services: Store, retrieve and move data files • (b) Print services: Control and manage access to printers • (c) Message services: Store, access and deliver data • (d) Application Services: Run software for network clients, Enable computers to share processing power

  13. Network Operating System (NOS) • System software controlling the network • Enables computers to communicate with each others • Two parts: • Network server • Coordinates: user accounts, information access, security, resource sharing • Workstation • Runs on top of the local OS • Sometimes integrated into the OS • Example: Novell NetWare, Microsoft Windows Server

  14. Transmission Media/Communication Channel • Physical pathways for sending data. • Two types: Cable media (twisted-pair, coaxial, fiber-optic); Wireless media (infrared LOS, HF radio signal, microwave • Effectiveness is influenced by: Bandwidth: Transmission capacity of a computer or a communications channel. Measured in megabits per second (Mbps). Bigger bandwidth = faster transmission Attenuation: Power of an electric signal weakens with distance. How far can a signal travel with the same properties and meaning? Shorter distance = lesser attenuation = faster transmission Electromagnetic interference (EMI): Interference by fluorescent light, weather or other electronic signals. Lesser EMI = faster transmission

  15. Cable Media: Twisted Pair Cable • Two or more insulated pairs of cable. • Unshielded (UTP): Telephone wire, Cheap and easy to install. Up to 1 Gbps at distance up to 100 meters. Rapid attenuation – sensitive to EMI and eavesdropping • Shielded (STP): Less prone to EMI and eavesdropping. More expensive and harder to install. 500 Mbps up to 100 meters

  16. Coaxial Cable • Components • Solid inner copper conductor • Plastic insulation • Outer braided copper or foil shield • Used for cable television and networks operating at 10-100 Mbps

  17. Fiber-Optic Cable • Components: • Light-conducting glass or plastic • Cladding (glass) • Tough outer sheath • Transmission: • Pulses of light • Immune to EMI and eavesdropping • Low attenuation • 100 Mbps to more than 2 Gbps • 2 to 25 kilometers

  18. Key Benefits & Drawback of media

  19. Wireless Media:Infrared Line of Sight • High frequency light waves • Distance of up to 24.4 meters • Attenuation, EMI and eavesdropping problems • Relatively inexpensive • Two types: • Point-to-point • Strict line of sight • Up to 16 Mbps at 1 meter • Example: TV remote • Broadcast • Devices don’t need to be directly in front of each other • Less than 1 Mbps

  20. Wireless Media: High Frequency Radio • Ideal for mobile transmission • Expensive due to cost of antenna towers • Complex installation • Susceptible to EMI and eavesdropping • Attenuation not a problem • Distance between nodes 12.2–40 kilometers • Rate up to several hundred Mbps • Examples: cellular phones and wireless networks

  21. Wireless Media: Microwave • High-frequency radio • Terrestrial microwave: Line-of-sight; Transmission up to 274 Mbps; EMI and eavesdropping problems; Cross inaccessible terrain; Alternative when cabling too ; expensive • Satellites microwave: Propagation delay; Satellites orbit 400-22,300 miles above earth; Typically 1-10 Mbps, up to 90 Mbps; Prone to attenuation; Susceptible to EMI and eavesdropping

  22. Relative Comparison of Wireless Media

  23. Network Topologies • Topologies: The physical layout of nodes and transmission media. Types include: • Star: All workstations connected to a central hub. Easy to lay out and modify. Most costly (cabling). Failure of hub can cause network failure. • Ring: Messages move in one direction around the circle. Covers large distances. Relatively little cabling. Failure of one node can cause network failure

  24. Network Topologies (ii) • Bus: Open-ended line. Easiest to extend. All nodes can receive the same message at the same time. Difficult to diagnose network faults • Mesh: Devices fully or partially connected to each other. Short routes between nodes. Many possible routes. Performs well in heavy traffic

  25. Protocols • Rules or procedures used to transmit and receive data • Specify: Connection of computers to the network, Error checking, Data compression, Signal of finished transmission, and Signal of received message • There are thousands of protocols: OSI, Ethernet, TCP/IP • Ex: Open system interconnection (OSI)

  26. Connectivity Hardware • Devices that facilitate transmission between two nodes. Include: • Connectors: Used to terminate a cable. Ex: RJ-45 connectors (twisted pair cable) • Network interface cards: PC expansion board. Allows computer to be connected to a network. Each NIC has a unique identifier • Modem: Enable transmission over telephone lines. Digital signal converted to analog

  27. Other Networking Hardware • Repeaters – replicate signal • Hubs – central point of connection • Bridges – connect two different LANs • Multiplexers – used when communication line is shared • Routers – connect 2 or more individual networks • Brouters – capabilities of bridge and router • Channel service unit – buffer between LAN and public carrier’s WAN • Gateway – performs protocol conversion

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