IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 TB-1 Technology Briefing Advanced Topics and Trends in Managing the Information Systems Infrastructure (telecommunication Network)

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 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 1-2

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Centralized Computing TB-3 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Distributed Computing TB-4 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Collaborative Computing TB-5 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 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) 1-6

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 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) 1-7

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Private Branch Exchange (PBX) TB-8 Telephone system serving a particular location  Connects phones and computers  Connects PBX to outside network Limited bandwidth because of limited phone line capacity

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 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 1-9

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Wide Area Network TB-10 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 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 1-11

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Network Services TB-12 (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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 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 1-13

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 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 1-14

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 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 1-15

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Coaxial Cable TB-16 Components  Solid inner copper conductor  Plastic insulation  Outer braided copper or foil shield Used for cable television and networks operating at Mbps

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Fiber-Optic Cable T B -17 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Key Benefits & Drawback of media 1-18

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Wireless Media: Infrared Line of Sight TB-19 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Wireless Media: High Frequency Radio TB-20 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Wireless Media: Microwave TB-21 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 ,300 miles above earth; Typically 1-10 Mbps, up to 90 Mbps; Prone to attenuation; Susceptible to EMI and eavesdropping

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Relative Comparison of Wireless Media TB-22

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Network Topologies TB-23 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Network Topologies (ii) TB-24 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Protocols TB-25 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 )

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Connectivity Hardware TB-26 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

IS Today (Valacich & Schneider) Copyright © 2010 Pearson Education, Inc. Published as Prentice Hall 10/10/2015 Other Networking Hardware TB-27 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