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Types of Computer Networks

Types of Computer Networks. By geographic distance Local Area Networks (LANs) Metropolitan Area Networks (MANs) Wide Area Networks (WANs) Personal Area Networks (PANs) also SANs By media Wired (copper, fiber), Wireless. How to set up/ troubleshoot your LAN. In the Windows search box

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Types of Computer Networks

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  1. Types of Computer Networks By geographic distance • Local Area Networks (LANs) • Metropolitan Area Networks (MANs) • Wide Area Networks (WANs) • Personal Area Networks (PANs) • also SANs By media • Wired (copper, fiber), Wireless Chapter 5 Local Area Networks

  2. How to set up/ troubleshoot your LAN • In the Windows search box type Network and Sharing Center • Click troubleshoot problems and investigate some of the options. The option Network Adapter will tell you the name of your wires connection. • Click Local Area Connection icon • Click Internet Options at the bottom left Chapter 5 Local Area Networks

  3. Information about LAN connections Chapter 5 Local Area Networks

  4. LANs • LANs are data networks of computers within a limited geographic area • LANs of wired and wireless technologies are frequently connected. • Protocols are standardized to facilitate interconnection, interface to manufacturers, module reuse • IEEE 802.x standards accepted by ISO Chapter 5 Local Area Networks

  5. Ethernet • “Ethernet” has 90+% of wired LAN market • Metcalfe and Boggs developed a wired LAN; first standardized LAN (IEEE 802.3) • Used coaxial cable (somewhat similar to cable TV); called it the “Ether” • Clamp for stations to attach to the cable (tap) • Station Interface Controller (NIC) to handle data translation and interference • With Xerox and Intel, placed in public domain Chapter 5 Local Area Networks

  6. Popular standards today • IEEE802.3 (wired LAN, called Ethernet) • Place command mode in search bar, type ipconfig | more • IEEE802.11 (wireless LAN, called WiFi) • FDU has a wireless network (using access pts) • IEEE802.15 (WPANs, specifically Bluetooth) Chapter 5 Local Area Networks

  7. Network devices • Nodes – devices on the network • Computers (Hosts or stations) • Network connecting devices • Routers, switches, hubs, gateways • Network peripherals (printers, scanners, storage devices) • Repeaters (boost signal) • Modem (used to connect to the Internet) Chapter 5 Local Area Networks

  8. Network Interface Card • NIC (or adapter) • Can be added onto the system board, attached to USB port, although typically NICs are bought with current systems • Laptops will have a wired and a wireless NIC • NICs contain a MAC (physical) address • NICs contain the network software (protocol) in firmware Chapter 5 Local Area Networks

  9. Client/server mode • Servers are frequently dedicated to specific applications • File server • Print server • Web server • (Multiple) client machines request services from servers • Clients connect to web servers Chapter 5 Local Area Networks

  10. Peer-to-peer mode • Workstations, laptops, etc. (perhaps using Bluetooth) cooperate in running the network and the devices • File sharing systems such as Kazaa, BitTorrent • Wi-Fi supports both peer-to-peer (ad hoc) and client-server (infrastructure) modes. Chapter 5 Local Area Networks

  11. Physical topology • Bus topology (MANs such as optimum on-line; original Ethernet implementation) • Star topology – local loop; switched Ethernet; cellular phones; Wi-Fi with access points • Tree topology (hierarchical) • Graph (WANs) Chapter 5 Local Area Networks

  12. Interconnecting networks • Bridges connect similar LANs • Gateways connect any types of networks • Typically used to connect home or school LAN to the Internet • Translate between different types of addresses, protocols, etc. • They all have to accommodate potential differences in speed Chapter 5 Local Area Networks

  13. Networks Links • Data travels either on cable or thru the air • Each data stream must be assigned a unique channel so that streams do not get garbled • The range of frequencies of the link (bandwidth) determines the maximum amount of transmission capacity • Bandwidth is measured in hertz (Hz); transmission capacity in bps Chapter 5 Local Area Networks

  14. Broadband or narrowband • Narrowband channels • Up to 56kbps for dial-up access • Broadband channels • Gigabit Ethernet (802.3ba 100Gbps) • 802.11n has maximum thruput of 100Mbps • Internet surfing would be slow on narrowband channels Chapter 5 Local Area Networks

  15. Transmission Noise • Data can be corrupted by noise, such as • Energy bursts • White noise • Different signals sent on the same frequency band (WiFi and Bluetooth devices use the same channels) • Hidden station problem • Network protocols recover from noise Chapter 5 Local Area Networks

  16. Packet Switching • Messages (phone calls, downloads, mail) are divided into smaller units called packets • Bits are added to allow them to be reassembled • Source and Destination addresses are added to each packet to allow individual routing • Packets can be multiplexed (combined) onto a higher speed line • Network protocols reassemble packets into messages, retransmit lost packets, etc. . Chapter 5 Local Area Networks

  17. Types of Network Addresses • MAC (physical) address is assigned to NIC • In Ethernet, in hardware by the manufacturer • A Domain address is assigned by The International Corporation for Assigned Names and Numbers (ICANN) to FDU, etc. • An IP desktop address may be assigned by DHCP or by your ISP (IPv4 and IPv6) • Network Apps are assigned ports by the OS Chapter 5 Local Area Networks

  18. Internet Infrastructure • Internet Infrastructure is maintained by NSPs (1st tier ISPs) • High speed routers deliver packets to destination • Links may be wired or wireless • Most infrastructure links are fiber • FCC obtained some free bandwidth by the replacement of analog television by digital television • For use as high speed wireless transmission channel Chapter 5 Local Area Networks

  19. Advantages of Wired Connections • Wired networks use cables, either fiber or copper (land phone lines, cable TV, FIOS) • Faster • More secure • Less noise • Typically easy to configure • Almost plug and play Chapter 5 Local Area Networks

  20. Disadvantages of wired connections • Inconvenient • People don’t like cables (rat’s nest) • Limited mobility • Harder to install LAN cables – perhaps through walls, ceilings • Harder to fix breaks in links • Animals have bitten through fiber cables • Copper wires have been dug up and sold Chapter 5 Local Area Networks

  21. Advantages of Ethernet • Public domain software • Many vendors manufacture equipment • NICs are cheap- typically included with a desktop or lap top • Mature and reliable • Very fast • Wi-Fi became popular because it is compatible with Ethernet Chapter 5 Local Area Networks

  22. Ethernet equipment • Get two or more Ethernet-ready computers • An Ethernet router • Surge strip • Cables for each computer • Twisted pair cat 5 or cat 6 • Internet access device such as modem • (router may provide all of these functions) Chapter 5 Local Area Networks

  23. Devices to connect computers • Hub, switch or router? • Hub – incoming data is resent to all stations • Cheap - you can get some for $5 to $15 • Switch • Sends data to destination computer only • More secure if you have multiple users on network • Router/ gateway • Connects to the Internet and switches data • Adapts to the speed of the sending devices Chapter 5 Local Area Networks

  24. Cabling • Network cables are terminated with RJ45 connectors (they look similar to telephone cables, but connectors are a bit larger) • Category 5 or 6 UTP recommended • Maximum length of about 100 meters (328 feet) • Just plug in the cables at each end Chapter 5 Local Area Networks

  25. Set up • Turn off all devices • Attach cables into ports in each pair of devices • Secure cables • Power up the devices (using surge strips) • OS should automatically detect and set up the network • Use network utilities, task bar to verify connection Chapter 5 Local Area Networks

  26. Wireless networks • Radio, microwave or infrared signals • Infrared – 1012 – 1014 Hz band • These do not go through objects • Used for channel changers • Microwave -108 – 1012 Hz band • Do not go through objects • Susceptible to interference by birds, rain • Used by satellites, long distance signals • Radio signals – 104 – 108 Hz band • go through most objects (not metal, stacked paper) Chapter 5 Local Area Networks

  27. FCC • In the U.S., frequency bands are assigned by FCC • Licensed bands are paid for by radio stations, television stations • Some bands are unlicensed and available to the public, but portions of these are agreed upon for specific usage • Garage door openers, pagers, wireless LANs Chapter 5 Local Area Networks

  28. Advantages of wireless networks • Mobility • No electromagnetic interference, specifically no power spikes (surges) • No cables, jacks • No breakage of cables, jacks • Ease of installation Chapter 5 Local Area Networks

  29. Disadvantages • Slower transmission rates • Signals must be boosted more often than wired LANs • Interference from other broadcasts and devices, some objects block transmission • Security • Broadcasts can be easily captured • Encrypt your data; lock your system Chapter 5 Local Area Networks

  30. Bluetooth • Bluetooth nodes set up peer-to-peer piconets with other devices • Limited distance; speed 2.4 GHz band up to 3Mbps; up to about 300 ft 6-9 GHz band up to 480 Mbps Appropriate for connecting devices together such as a mouse to a computer Also connects cell phones to a wireless headset Chapter 5 Local Area Networks

  31. Wi-Fi speed • The term Wi-Fi refers to a set of IEEE 802.11 standards: 802.11b, a, g, n, y • Frequencies used by b, g, and n are in the 2.4GHz unlicensed band, same as basic Bluetooth and some cellular phones • Bluetooth is slower, and typically its signals knock out 802.11 (not vice versa) • g and n are backward compatible with b Chapter 5 Local Area Networks

  32. Speeds of Wi-Fi • Speeds of about 11 Mbps (b), 54 Mbps (g), 144Mbps (100Mbps throughput) for n Chapter 5 Local Area Networks

  33. Wi-Fi • Wi-Fi LANs require an access point (base station) in infrastructure mode • Functionality can be built into wireless router • Stations transmit to access point which then forwards packets to destination station of LAN, or out through a wired connection to the Internet • All wireless devices must have at least one antenna to receive and send packets Chapter 5 Local Area Networks

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