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"Part I Understanding Information Systems Technology" I 5 NETWORKING TECHNOLOGIES Information Systems Technology Ross Malaga Copyright © 2005 Prentice Hall, Inc. 5-1 LEARNING GOALS • Describe the components of a telecommunications system. • Compare and contrast the various types of transmission media • Identify and explain the various types of computer networks. • Identify and describe the role of the major hardware items used in networks. • Describe the importance of networking protocols and identify the major ones used in business. • Identify and describe the role of software used in networks. • Describe the function of telecommunications services. • Explain the importance of network planning and the major components of a network plan. Copyright © 2005 Prentice Hall, Inc. 5-2 Bead Bar Consultant Networking Needs • Meredith – How to build a network when there is no premises wiring? • Suzanne – Need to connect all locations • Leda – Connectivity would allow easier exchange of ideas with franchisees • Mitch – Remote access to corporate network from anywhere • Julia – Minimize costs and improve data collection and communications with all locations • Miriam – Electronic sales data and marketing materials • Rachel – Work flow systems to reduce paperwork • Jim – Use of electronic forms instead of paper forms Copyright © 2005 Prentice Hall, Inc. 5-3 Telecommunications Systems • Purpose – to transmit data from one location to another – – – – Voice data Computer data Video data Any data – – – – – – Transmission media Network topology Data communications hardware Protocols used in system Network software Telecommunications services • Major components Copyright © 2005 Prentice Hall, Inc. 5-4 Data Format for Network Transmission • Data inside computers is in digital form • Networks transmit two forms of data – Analog – voice over telephone – Digital – data over ISDN telephone line • Analog network cannot carry digital data – Most of existing telephone system is an analog network • Conversion of digital data to analog format (when necessary) – Modulation • Amplitude modulation • Frequency modulation – Convert on one end of transmission; de-convert on other end – Modulation–demodulation, or modem for short Copyright © 2005 Prentice Hall, Inc. 5-5 How Modems Work Copyright © 2005 Prentice Hall, Inc. 5-6 Bandwidth • The measure of capacity of transmission media • Bits per second (bps) – Kilobits per second • Modem communications over telephone lines – Megabits per second • Most existing local area networks – Gigabits per second • High speed data networks – Internet backbone Copyright © 2005 Prentice Hall, Inc. 5-7 Network Media • Physical media – Electrical signal • Wire – Twisted pair » Phone System » LAN – Coaxial • Signal interference – Optical signal • Fiber optic cable – Thin glass fibers surrounded by coating – Uses lasers for light source – Very fast – Physical media require installation of cable • Expensive • Time consuming Copyright © 2005 Prentice Hall, Inc. 5-8 Copyright © 2005 Prentice Hall, Inc. 5-9 Network Media • Wireless media – Radio frequency • • • • Low power radio waves Affected by electromagnetic interference Highly vulnerable to snooping Conflicting standards – IEEE 802.11a, b, and G • Limited distance – Terrestrial microwave • Tower • Satellite – Geosynchronous – GEO – Medium earth orbit – MEO – Low earth orbit – LEO – Infrared • Close proximity and “line of sight” location required Copyright © 2005 Prentice Hall, Inc. 5-10 Media Types and Speed Copyright © 2005 Prentice Hall, Inc. 5-11 Computer Networks • Two or more computers that are connected for the purpose of sharing data – File sharing (e.g. MP3s) – E-mail – Database sharing • Computer must be connected to the network media – Network interface card (NIC) – Each NIC has its own unique address • Once connected to the network, the computer (or other device) becomes a network node Copyright © 2005 Prentice Hall, Inc. 5-12 Transmitting Data in a Network • Circuit switched network – Entire circuit from end to end must be open and available – Guarantees message goes through – Any one segment along the way goes down, the circuit is disabled • Packet switched network – Message data divided into small pieces called packets, each with destination address and packet id – Special network hardware routes packets to destination where message is reassembled – More fault tolerant than circuit switched networks Copyright © 2005 Prentice Hall, Inc. 5-13 Network Topologies • The configurations of network components • Widely used network topologies – – – – – – Bus Star Ring Mesh Tree Hybrid Copyright © 2005 Prentice Hall, Inc. 5-14 Bus Network Topology • Most simple network topology • All devices connected to a common central cable • Inexpensive • Easily expanded • If cable fails, the entire network will shut down • Bus is topology used most widely in businesses Copyright © 2005 Prentice Hall, Inc. 5-15 Bus Network Topology (Continued) Copyright © 2005 Prentice Hall, Inc. 5-16 Star Network Topology • Star topology is centered around central routing device called a hub • All network nodes connect to the hub • Easy to install and update • If hub fails, network fails • Hub can also be a bottleneck Copyright © 2005 Prentice Hall, Inc. 5-17 Copyright © 2005 Prentice Hall, Inc. 5-18 Ring Network Topology • Each node connected to two other nodes in a ring • Similar to the buss, but with the ends of the buss connected together • More reliable than buss or star – If one node fails, data rerouted around failed node • Expensive and difficult to install – Usually used by larger organizations who can afford the expense and to whom the reliability is very important Copyright © 2005 Prentice Hall, Inc. 5-19 Ring Network Topology (Continued) Copyright © 2005 Prentice Hall, Inc. 5-20 Mesh Network Topology • Every node connected to every other node • Fast • Reliable – No hub or bus to fail – If one device goes down, it is the only node affected • Expensive – Every node must be wired to every other node • Difficult to add nodes – If there are 32 nodes in a mesh network and you wish to add a new node, how many new cables must you add? Copyright © 2005 Prentice Hall, Inc. 5-21 Copyright © 2005 Prentice Hall, Inc. 5-22 Tree Network Topology • Combination of bus and star • Two or more star networks connected using a bus for the backbone Copyright © 2005 Prentice Hall, Inc. 5-23 Copyright © 2005 Prentice Hall, Inc. 5-24 Hybrid Topologies • Combine two or more of the other topologies • Bus used for LANs and ring used for campus backbone linking LANs together Copyright © 2005 Prentice Hall, Inc. 5-25 Copyright © 2005 Prentice Hall, Inc. 5-26 Network Architecture • Defines how network functions at a logical level • Two primary types – Client-server – Peer-to-peer (P2P) Copyright © 2005 Prentice Hall, Inc. 5-27 Client-server Network Architecture • Nodes are either clients or servers • Clients use services • Servers provide services – – – – Access to shared data E-mail Printing FAX • Client software on client node cooperates with server software on server node – WWW is largest client server application Copyright © 2005 Prentice Hall, Inc. 5-28 Peer-to-Peer Network Architecture • All nodes on the network are equal. • Any node can be both a client and a server. • Napster was an example of a P2P network used to share MP3 files. • Windows printer and file sharing use P2P. Copyright © 2005 Prentice Hall, Inc. 5-29 Copyright © 2005 Prentice Hall, Inc. 5-30 Local Area Networks (LANs) • Computer network where the nodes are all in close proximity – Department – Floor in office building – Small business building • Provides access to shared resources – – – – Servers Printers Databases Internet access Copyright © 2005 Prentice Hall, Inc. 5-31 Larger Networks • Campus area network (CAN) – Connects LANs within a limited geographic area • School • Corporate campus • Military installation • Metropolitan area network (MAN) – Within a town or city • Wide area network (WAN) – Two or more LANs that are geographically separate but linked through a public telephone network Copyright © 2005 Prentice Hall, Inc. 5-32 Data Communications Hardware • • • • NIC Hub Modem Router – special hardware in packet switched networks that determines optimal routing path for packets • Gateway – converts data from one standard to another; allows connections of disparate networks Copyright © 2005 Prentice Hall, Inc. 5-33 Protocols • • An agreed upon set of rules that govern communications in a network TCP/IP – – – – The protocol suite for the Internet Transmission Control Protocol (TCP) • Provides a reliable byte-stream transfer service between two endpoints on an internet Internet Protocol (IP) • Defines a delivery mechanism for packets of data sent between all systems on an Internet Widely used by business, even for internal networks Copyright © 2005 Prentice Hall, Inc. 5-34 Protocols (Continued) • Ethernet – – – – – – – A set of rules for constructing message in a local network Most widely used protocol for transmitting data over LANs Listen before talk Simple Inexpensive Flexible Collisions • High message volume greatly reduces transmission speed Copyright © 2005 Prentice Hall, Inc. 5-35 Protocols (Continued) • Token Ring – – – – – – Also a set of rules for constructing message in a local network Only one node “talks” at a time Complex Expensive More fault tolerant than Ethernet No collisions • Transmission speed unaffected by message volume Copyright © 2005 Prentice Hall, Inc. 5-36 Network Software • Network operating system – Novell NetWare – Microsoft Windows Server 2003 • Network management software – – – – Helps ensure security of network Monitors performance Helps administrators reconfigure network Remote administration via push technology • Network monitoring software – Packet sniffers – see data as it moves over network – Keystroke monitors – see what users are doing Copyright © 2005 Prentice Hall, Inc. 5-37 Telecommunications Services • Value Added Networks (VANs) – Proprietary networks built using common carriers – Provide enhanced services • Video conferencing • Electronic data interchange (EDI) • Virtual Private Networks (VPNs) – Use encryption to provide a secure end-to-end connection over common carriers or the Internet – Remote access to internal networks w/o dialup • Leased lines – High speed, long distance data transfer Copyright © 2005 Prentice Hall, Inc. 5-38 Leased Line Comparisons Copyright © 2005 Prentice Hall, Inc. 5-39 Bead Bar Consultant • How can the Bead Bar use networking technologies? – – – – – – Meredith – Wireless connections Suzanne – Connect all studios to org. software Leda – Remote access to org. software for franchisees Mitch – Can we access from onboard ships, also? Julia – Cost benefits of wireless networking Miriam – Improved inventory control due to more rapid transmission of sales and inventory data – Rachel – Improved efficiency – Jim – Will we need a network administrator? How about new policies and procedures for using and accessing the network? Copyright © 2005 Prentice Hall, Inc. 5-40 Learning Goals Summary In this chapter you have learned: The components of a telecommunications system To compare and contrast the various types of transmission media To identify and explain the characteristics of various types of computer networks To identify and describe the role of the major hardware items used in networks The importance of networking protocols and identify the major ones used in business To identify and describe the role of software used in networks The function of telecommunications services The importance of network planning and the major components of a network plan Copyright © 2005 Prentice Hall, Inc. 5-41