Networks and Communication Technology.docx

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Computer Science
Computer Science 1032A/B
Diane Goldstein

Networks and Communication Technology Computer Network  Computers tend to be more useful when connected to networks  Network o Collection of computers o Communication over transmission line  Types o Local area network (LAN) – single physical site o Wide area network (WAN) o Internet LAN – Local Area Network  Computers connected together at a single physical site o Any number of computers o One small geographic area o Communication lines placed where they are needed WAN – Wide Area Network  Connect to computers in different geographical areas – physically separated  Use a variety of communication networks – licensed by government The Internet and Internets  Network of networks  Connect LANs, WANs, and other internets  The Internet o Sending email and browsing  Internets o Private networks of networks  Uses a variety of communication methods and conventions  Layered protocols provides a seamless flow of data Problem in the 60’s  Incompatible computers o Operating systems, hardware, software o Primitive communications technology  Solution o ARPANET (Advanced Research Projects Agency Network) o 1969 – requested by department of defence o Its technology spawned the internet Components of a LAN  Switch o Special purpose computer that receives and transmits messages in the LAN o May have more than one per LAN  Network Interface Card (NIC) o Hardware to connect each device to the cable o Built-in NIC or expansion slot card  MAC (Media Access Controller) address o Unique identifier LAN Network Protocol  All devices use the same protocol  Institute for Electrical & Electronic Engineers (IEEE)  Create and publish standards  LAN protocols from IEEE 802 committee  IEEE 802.3 or Ethernet  Specifies: hardware or characteristics, message packaging and processing  PC supports 10/100/1000 Ethernet NICs LANs with Wireless Connections  Wireless NIC (WNIC)  LAN operation  NICs – 802.3 protocol  WNICs – 802.11 protocol (Wi-Fi)  WNICS connect to Access Point (AP) Connecting to the Internet  The Internet is a wide area network (WAN)  Connecting to computers at separate points o Unable to use cables between sites o Obtain use of connections from licensed communication companies o Routers implement the protocol for WANs Connecting to the Internet  Individual computer connection via router to an ISP  Internet service provider (ISP) o Legitimate Internet address o Gateway to the Internet o Fee for use of Internet Name and Addresses  Rules exist for naming sites o Top level domain (TLD) - .ca, .com, .org, .biz  Address on the internet o Uniform resource locator (URL)  Logical address (IP address) o Comprised by four sets of number separated by periods IP Address  Two kinds: o Public  Used on the internet  Assigned by ICANN to ISPs and institutions  ICANN (Internet corporation for assigned names and numbers)  Each address is unique o Private  Used within private networks  Controlled by company operating network Dynamic Host Configuring Protocol  IP address assigned dynamically  Distributes temporary IP address o Address used while connected to LAN (plugged or wireless) o When disconnected, IP address made available Domain Name System  DNS o Translates URL names into IP addresses o Resolves domain name o ICANN manages resolution systems  Domain name resolution o Conversion o Domain name – IP address o Performed by Domain Name Resolvers Modems (Internet Connections)  Dial-Up Modems o Uses telephone lines o Interferes with voice telephone service o Dial ISP for connection  DSL Modems o Digital subscriber line (DSL) o Operates over telephone lines (twisted pair) o No interference with voice service, faster data transmission then dial-up o Connection always maintained o Uses its own p
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