Unit E.ppt

Computer Concepts, 6th Edition – Illustrated Unit E Networks and the Internet 1  Objectives Describe the basic components of a network Explain the methods of data transmission, including types of signals, modulation, and choices a...

Computer Concepts, 6th Edition – Illustrated Unit E Networks and the Internet 1  Objectives Describe the basic components of a network Explain the methods of data transmission, including types of signals, modulation, and choices among transmission modes Differentiate among the various kinds of communications links and appreciate the need for protocols List the components , types, and protocols of a local area network Computer Concepts 6th Edition – Illustrated  Objectives Appreciate the complexity of networking Describe some examples of networking Computer Concepts 6th Edition – Illustrated  Data Communications Data Communications System – computer systems that transmit data over communication lines such as telephone lines or cables – Centralized Data Processing – Distributed Data Processing – Network Computer Concepts 6th Edition – Illustrated  Communications Network The combination of hardware, software and connecting links that transport data Data is encoded, sent to its destination then decoded Noise Encoded Decoded Data Signal Data Communications Channel Source Transmitter Receiver Destination Computer Concepts 6th Edition – Illustrated Shared Resources Networks share hardware, software, and data Sharing reduces costs – Peripheral devices, site licenses Provides access to Internet Share data – Groupware, e-mail, IM, online conferencing Computer Concepts 6th Edition – Illustrated Shared Resources (cont.) Networks are vulnerable – Unauthorized access – Malicious code Viruses, Trojan horses, worms Networks are becoming more standardized Most benefits outweigh risks – Computers can be protected Computer Concepts 6th Edition – Illustrated  Network Classifications by Geographic Coverage PAN: Personal Area Network (PDAs) WAN: Wide Area Network (Internet) NAN: Neighborhood Area Network (popular with coffee shops) MAN: Metropolitan Area Network (50 miles) LAN: Local Area Network (single building) Computer Concepts 6th Edition – Illustrated Network Classifications by Organizational Structure Client/Server: – One or more computers configured as servers and other computers configured as clients – Server is central repository for data Peer-to-Peer (P2P): – Treats every computer as an equal – Workstations transfer data to each other without going through server – File-sharing networks Computer Concepts 6th Edition – Illustrated Network Classifications by Organizational Structure Computer Concepts 6th Edition – Illustrated Client/Server Terminology Server: A computer connected to a network that distributes resources to network users Host: Like a server, but mostly used for Internet services Workstation: PC connected to a network Client: Software that allows access to server services Computer Concepts 6th Edition – Illustrated  Network Classifications CATEGORY DESCRIPTION EXAMPLES Geographical Area where network PAN, LAN, WAN, NAN, devices are located MAN Organizational Hierarchy of devices Client/Server, P2P Physical Layout and relationship Star, bus, ring, mesh, tree between devices Network Technologies for cables Twisted-pair, coaxial, or and signals that carry fiber-optic cable; RF; data microwaves; Infrared; power or phone line Bandwidth Capacity of network Broadband, narrowband Communications Standards for orderly & TCP/IP, SPX/IPX, protocols safe data transfer NetBEUI/NetBIOS, AppleTalk Computer Concepts 6th Edition – Illustrated  Network Topology Physical arrangement of devices, cables, and wires Each connection point on a network is a node: – Server, workstation, network peripheral, network device Physical address: built into circuitry Logical address: assigned by network software Computer Concepts 6th Edition – Illustrated  Network Topology Star Bus Ring – 5 common topologies –Star (central connection point) –Ring (connects devices in a circle) –Bus (common backbone) –Mesh (each device connected to others) –Tree (blend of star and bus) Computer Concepts 6th Edition – Illustrated Interconnecting Networks Two similar networks can be connected by a bridge – Transfers data without regard to format Gateway – A device or software used to join dissimilar networks by making data compatible Router – Electronic device that connects 2 or more networks Computer Concepts 6th Edition – Illustrated Network Hardware Overview Computer Concepts 6th Edition – Illustrated  Network Hardware Network Interface Card (NIC) – Example: Ethernet card Connection Devices – Modem: converts PC digital signals – Hub: connects nodes on a LAN – Router: decides best way to route data on network – Gateway: entrance to another network – Transceiver: sends and receives data on a wireless network – Repeater: amplifies and regenerates signals Computer Concepts 6th Edition – Illustrated  Wired Communication Channels Twisted-pair cables (phones) – STP: shielded twisted pair – UTP: unshielded twisted pair for small networks Coaxial cable (television) – High capacity Fiber-optic cable – Pulses of light in thin glass tubes – Essential to Internet backbone Computer Concepts 6th Edition – Illustrated Wireless Communication Channels RF: radio frequency signals – Send and receive by a transceiver with antenna Microwaves – More capacity than radio waves – Need clear path between transmitter and receiver – Cannot penetrate metal objects Computer Concepts 6th Edition – Illustrated Wireless Communication Channels Satellites – Signal relayed from ground station to satellite – Transponder on satellite receives, amplifies and retransmits signal back to earth – Key technology for Internet backbone Computer Concepts 6th Edition – Illustrated Wireless Communication Channels Infrared light – Short distance with clear line of sight – Example: connect notebook with printer Laser light – Larger distance with clear line of sight – Example: between buildings in future Computer Concepts 6th Edition – Illustrated  Bandwidths The transmission capacity of a communications channel measured in bps (bits per second) Low bandwidth carries less data than high bandwidth – Telephone – Narrowband High bandwidth – Coaxial cable – DSL lines – Called broadband Computer Concepts 6th Edition – Illustrated  HomePNA and HomePLC HomePNA – Uses existing telephone wiring to connect network devices – Special NIC and cable to connect computers to phone jacks – Can use phone and Internet at the same time HomePLC – Uses special NIC and cable to connect computers to electrical outlets – Data transmitted as radio waves – Appliances, radios, and baby monitors affect signal Computer Concepts 6th Edition – Illustrated  Transporting Data Protocols: rules for successful and accurate data transmission Handshaking: devices communicating with each other Packet Switching: determines how data is broken up Circuit Switching: establishes a dedicated, private link between phone lines during a call – Inefficient because it reserves a circuit even if data is not being transmitted Computer Concepts 6th Edition – Illustrated Communications Protocol Allows two devices to negotiate and agree on how data will be transmitted TCP/IP – Transport Control Protocol/Internet Protocol – Most common – TCP: breaks data into packets – IP: addresses packets Computer Concepts 6th Edition – Illustrated  Internet Protocols PROTOCOL NAME FUNCTION TCP/IP Transmission Control Addresses and breaks Protocol/Internet Protocol messages into packets HTTP Hypertext Transfer Protocol Exchanges information over the Web FTP File Transfer Protocol Transfers files between local and remote hosts POP or Post Office Protocol or Transfers mail from an e- IMAP Internet Mail Access Protocol mail server to a client SMTP Simple Mail Transfer Transfers mail from a client Protocol to an e-mail server TELNET Telecommunications Allows users to access Network multiple hosts SSL Secure Sockets Layer Provides secure data transfer Computer Concepts 6th Edition – Illustrated  VoIP Voice over IP or Internet telephony Uses Internet packets to transmit voice You cannot use the same phone line for voice calls while using your ISP, but you can use VoIP Used to play and chat about games over the Internet Computer Concepts 6th Edition – Illustrated  LAN Standards Institute of Electrical and Electronics Engineers (IEEE) IEEE designation numbers identify compatible network technologies – ARCnet: old, simple, inexpensive Legacy systems – Token Ring: ring topology – FDDI: fiber-optic cables – Ethernet: simultaneous broadcast of data packets Computer Concepts 6th Edition – Illustrated  Ethernet Packet accepted only by device to which it is addressed Refers to a family of LAN technologies – Various transmission rates – Fiber-optic and twisted-pair cables – Bus or star topology Connect many workstations Computer Concepts 6th Edition – Illustrated  Ethernet CSMA/CD protocol helps avoid collisions Computer Concepts 6th Edition – Illustrated Home Ethernet Equipment Ethernet card in each workstation and peripheral device Link between network nodes such as cable Central connection point (hub) Uplink port can connect several hubs Computer Concepts 6th Edition – Illustrated  Wireless Standards Wi-Fi (Wireless Fidelity) – Set of wireless networking technologies – Defined by IEEE 802.11 standards – Compatible with Ethernet – No license required Absence of cables enables portability Desirable for notebook and tablet computers Computer Concepts 6th Edition – Illustrated  Wi-Fi Disadvantages Speed – Radio waves Distance – 25-150 feet Security – War driving/LAN-jacking – Wired Equivalent Privacy: encryption Computer Concepts 6th Edition – Illustrated  Wi-Fi (cont.) Wi-Fi cards required – Include transceiver and antenna – Can be added to notebooks, PCs, and Tablets – Wireless access point is same as hub or router in Ethernet Bluetooth makes short-range wireless connections between devices such as a mouse, keyboard, printer Computer Concepts 6th Edition – Illustrated  Internet Connections The Internet isn’t owned or operated by corporations or governments Traffic exceeds 100 trillion bytes (terabytes) each week Backbone provides high-speed routes for data traffic – Links and routers maintained by NSPs (Network Service Providers) like AT&T Computer Concepts 6th Edition – Illustrated  Internet Connections Users connect to Internet Service Provider (ISP) or through LAN ISP provides e-mail and access to Web – Handle the physical aspects of transmitting and receiving data – Maintain servers for IM, chat groups, FTP – Installation charges and monthly fees Computer Concepts 6th Edition – Illustrated  Internet Connections Ping software: Packet Internet Groper – Checks internet pathways to be sure they are open and adequate Traceroute software – Traces data paths Modem speed – Speed is actually a measure of capacity – Measured in bits per second (bps) – Most are faster downstream than upstream Computer Concepts 6th Edition – Illustrated  IP Addresses ISP gives unique IP address to subscriber Series of numbers in 4 parts – 204.127.129.001 Static IP address: permanent, usually servers Dynamic IP address: temporary, for one session Look at your Internet configuration settings to find your IP address Computer Concepts 6th Edition – Illustrated  Domain Names Translates directly into IP address Examples: course.com, rutgers.edu Top-level domain: indicated by extension ICANN handles domain name registration and control edu edu info info mil mil org org com com gov gov int int net net Computer Concepts 6th Edition – Illustrated  Register a Domain Name 1. Find out if name is currently used or reserved 2. If not available, use a different top-level domain 3. Fill out a form online Computer Concepts 6th Edition – Illustrated Connect to the Internet with POTS Plain old telephone service – Dial-up connection via voiceband modem – Circuit switching gives continuous private link Modem: – Modulate/demodulate – Computer sends digital signals, modems convert to analog Computer Concepts 6th Edition – Illustrated DSL: Digital Subscriber Line High-speed and always-on Digital communication links for voice and data Uses standard copper phone cables – Fastest and most affordable for individuals – Variations are ADSL, SDSL, HDSL AND DSL lite – 1.5 Mbps downstream Computer Concepts 6th Edition – Illustrated ISDN: Integrated Services Digital Network All-digital, carries voice and data Mostly used for business LANs Faster than dial-up, slower than DSL or cable T1, T3, or T4 Used by businesses and ISPs on dedicated leased lines Computer Concepts 6th Edition – Illustrated Cable Internet Connections Satellite dish “farm” or head-end – Where TV broadcasts are received and retransmitted for cable connections Bandwidth provides signals for TV, incoming and outgoing data You need – Ethernet card – Cable modem: usually ISP provides – Splitter to connect both modem and TV Computer Concepts 6th Edition – Illustrated Cable Internet Connections (cont.) Bandwidth issues – Could slow down as more neighbors use service Security issues – DOCSIS-compliant cable modems Filters packets to certain ports Secures your computer from your neighbors Doesn’t close up all security holes associated with always-on connections Computer Concepts 6th Edition – Illustrated Security When Always-On Same IP address when on – hackers can use High-speed access desirable for hackers Turn off machine often Computer Concepts 6th Edition – Illustrated Wireless Internet Connections DSS: Direct Satellite Service – Dishes are owned/leased by individuals – Can be blocked by adverse weather – Subject to latency delays Fixed wireless – Broadcasts RF data signals over large areas – Used by homes and businesses – Less latency than DSS – Ethernet-compatible, a large Wi-Fi Computer Concepts 6th Edition – Illustrated Wireless Internet Connections Public Wi-Fi – Range of coverage: hotspot – Open to public: free, subscription, fees WAP (wireless access protocol) – Handheld devices Cellular-ready modems – PC cards for notebooks or tablets – Transfers data using cell phone service Computer Concepts 6th Edition – Illustrated Connect to the Internet with Handheld Devices Screen size and color Keyboard functionality Network connection options Band depends on where you will use it (tri-band for Europe) Features such as SMS, MMS, cameras Computer Concepts 6th Edition – Illustrated TechTalk: Installing a LAN Install Ethernet NIC – On motherboard or with PC card; both have port for network cable Attach cable to NIC port and hub port Turn on PC Windows should automatically detect and establish connection Can activate file sharing and drive mapping by using Windows Network Neighborhood Computer Concepts 6th Edition – Illustrated  Context: Education Categories – CBT (computer-based training) – CAL (computer-aided learning) – CAI (computer-aided instruction) – Simulations 99% of American public schools have computers – Not all students have daily access Some colleges require incoming students to have a computer DE/DL (Distance Education/Learning) Computer Concepts 6th Edition – Illustrated  Issue: Free Wi-Fi? Free WLANs No license to set up a Wi-Fi Can reduce bandwidth for paying customers Are they legal? Computer Concepts 6th Edition – Illustrated  Unit Summary Networks offer shared resources Networks classified by: – Geography – Topology – Organizational structure – Links – Bandwidth – Protocols Computer Concepts 6th Edition – Illustrated Networks and the Internet End 54