Communication and Network

Twisted - Pair

• Least expensive and most widely used
• Consists of two insulated copper wire arranged in a regular spiral patter, act as a single communication link
• Used to transmit both analog and digital signals. Analog signals amplifiers are required about every 5 to 6 km. Digital signals, repeaters are required every 2 or 3 km.
• Commonly used medium for in the telephone network.
• Come in two varieties which are Unshielded Twisted Pair ( UTP ) Cable and Shielded Twisted Pair ( STP ) Cable.

• Coaxial Cable
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• • Contains thick, conductive metal wire at the center that is surrounded by meshed or braided metal shield along the same parallel axis.
  • Used for high-speed data transmission over distance of several kilometers.
  • Commonly used for radio antennae, cable TVs and LAN applications.
  • Can transmit signals greater distances and at a higher bandwidth.
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  Fiber - optic cable
  
  
• • Offers higher bandwidth and lower signal losses.
  • Allows higher data rates over longer distances.
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• Advantages of using :
• Information carrying capacity – Fiber optic capacities are well in excess of that required by today’s network applications. If the wavelength is different, the actual bandwidth can rise up to 5Cbps.
• Low signal loss – optical fibers offer low signal loss. It permits longer transmission distances. In comparison with copper, the longest recommended copper horizontal link is 100 meters; when using fiver it is 2000 meters or more.
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  Node
  
  
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  Client
  
• Communicates only with server, not with other clients.
• A standard PC that is running an operation system such as Windows 9x, Windows Me, Windows 2000 Professional, or Windows XP.
• Windows contain the client software that enables the client computers to access the resources that servers share.
• The connection in between the client and server is maintained only during the actual exchange of information.
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  Server
  
  
• Refers to the various type of software that process the requests from a visitors to a website.


• Used for running larger programs for multiple users often simultaneously and typically accessed only via a network.
• Maintained and housed by the institution or organization that sets up the CMC.
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  Hub
  
  
• Commonly used LAN connectivity devices ( although inexpensive switches are rapidly replacing hubs on networks)
• Serve as a central connection points for LANS.
• Contains no active electronics and therefore cannot be used to extend a LAN.
• Organizes your cable and relays data signals to all the computers on the LAN.
• Used on network that use twisted-pair cabling.
• A new HUB can be attached to the current HUB, thus providing greater port density.
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  Network Interface Card ( NIC )
  
  
• Hardware component that connects a station to the network medium.
• An adapter that plugs into a computer, enabling it to connect to a local area network(LAN) for the purpose of communicating with other computers and devices.
• Can be configured to improve the performance or security of data transfer between the station and the network.
• To improve network security, a NIC can be configured to apply encryption to all messages before transmission.
  
  Network Operation system ( NOS )
  
  
• Communicates with the PC hardware to make connection between the machines
• Provides basic file and supervisory services over a network.
• Provide a structure for access to application
• Enable users to manipulate programs and data
  
  Host Computer
  
  
  Receive calls from other computer and stores information that can be retrieved.
  Computer that access the host computer are called remote computers.
  
  Network Manager
  
  
• Provides one-stop shopping for all of your network configuration needs.
• Usually considered someone who maintains an existing network, making sure it runs as smoothly as possible, making adjustments for new users and programs and solving problems.