Computer Systems


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Computer Systems

  1. 1. Computer Systems Networking Health Informatics Elective Meds 2006
  2. 2. Outline Types of Networks Client/Server Peer-to-peer Local area network (LAN) Wide area network (WAN) The Internet
  3. 3. Peer to Peer Network
  4. 4. Peer-to-peer Wired Operating System (Windows NT; MacOS) Transmission speeds – twisted pair wire - Cat 5 – 100 Mbps; coaxial cable) Distance – max 500 m with 10base5 Wireless Standards – e.g. 802.11b Distance – proximity to a wireless hub
  5. 5. Local Area Networks Usually same operating systems; may or may not be same computer configuration May be arranged in different topologies (e.g. star, bus, ring) Different protocols (set of rules) used for communication (e.g. NETBios/NETBeui (MS); IPX/SPX (Novell); TCP/IP (Unix) Client-server model
  6. 6. Server Client
  7. 7. Star-like network. Each peripheral unit has its own connection with the central computer.
  8. 8. Network in which a bus structure is used.
  9. 9. Local Area Networks A computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. Most LANs connect workstations and personal computers. Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it also is able to access data and devices anywhere on the LAN. This means that many users can share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions. There are many different types of LANs Ethernets being the most common for PCs (10 Mbps on Cat 3, 4, 5; 100 Mbps on Cat 5 wire). Most Apple Macintosh networks are based on Apple's AppleTalk network system, which is built into Macintosh computers.
  10. 10. Wide Area Networks May be different operating systems across the network.
  11. 11. Router WAN - Wide Area Network Backbone
  12. 12. Wide Area Networks A computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more local-area networks (LANs). Computers connected to a wide-area network are often connected through public networks, such as the telephone system. They can also be connected through leased lines (coaxial or fibre- optic cable) or satellites. The largest WAN in existence is the Internet.
  13. 13. 1nn.nn.n.nn 1nn.nn.n.nn IP Address Internet
  14. 14. The difference between the Internet and the W3 Many people use the terms Internet and World Wide Web interchangeably, but the two terms are not synonymous. The Internet and the Web are two separate but related things. The Internet is a massive network of networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known as protocols. The World Wide Web, or simply the Web, is a way of accessing information over the medium of the Internet. It is an information-sharing model that is built on top of the Internet. The Web uses the HTTP protocol, only one of the languages spoken over the Internet, to transmit data. Web services, which use HTTP to allow applications to communicate in order to exchange business logic, use the Web to share information. The Web also utilizes browsers, such as Internet Explorer or Netscape, to access Web documents called Web pages that are linked to each other via hyperlinks. Web documents also contain graphics, sounds, text and video. The Web is just one of the ways that information can be disseminated over the Internet. The Internet, not the Web, is also used for e-mail, which relies on SMTP; Usenet news groups; instant messaging; and FTP. So the Web is just a portion of the Internet, albeit a large portion, but the two terms are not synonymous and should not be confused.