NETWORK CONNECTIVITY DEVICES
 • Network  media,  both  bounded  and  unbounded  carry  the  data 
  across  the  network.  To  move  data  around  the  network  on  the 
  media, and to create networks, network connectivity devices are 
  needed. (means of communication)
 • Network connectivity devices make networks happen. They connect 
  clients to the network and assist in moving data around a network 
  in most efficient manner.
 • In  some  cases,  network  devices  can  boost  the  data  signal  to 
  increase the distance your data transmissions can travel before they 
  are so degraded that they are unusable at their destinations. 
 • Each of these devices fulfils a specific role in a network; however, 
  only the largest and most complex environments use all of them.
    NETWORK INTERFACE CARDS (NIC)
 • NIC is a device that serves as an intermediary between 
  the computer’s data bus and the network. 
 • To connect to a network, a PC must have a NIC. 
 • NICs can be built into the motherboard of the computer, 
  connected through a USB, PC card or Fire wire port or 
  can be an internal adapter card that is installed into one 
  of the computer’s expansion slots. 
 • It can also be called a network adapter, LAN adapter or 
  network  card.  The  mechanisms  by  which  computers 
  connect to a network.
 • NICs come in all shapes and sizes and they come 
  in prices to suit all budgets.
 • For port compatibility, generally a NIC has only 
  one port, for twisted-pair cabling. If some other 
  connectivity  is  required,  the  card  should  be 
  specified  accordingly:  a  fiber-optic  or  coaxial 
  cable port. 
 • For hardware compatibility, before installing a 
  network  card  into  a  system,  compatibility 
  between  the  network  card  and  the  operating 
  system on the PC must be verified.
 • NIC interfaces come as add-in expansion cards or as PCMCIA cards used in 
  laptops  systems.  Sometimes,  the  interface  is  embedded  into  the 
  motherboard rather than having an add-in NIC.
 • A network interface typically has at least two LEDs that indicate certain 
  conditions:
 • Link light: this LED indicates whether a network connection exists between 
  the card and the network. An unlit link light is an indicator that something 
  is awry with the network cable or connection.
 • Activity light: this indicates network activity. Under normal condition, the 
  light should flicker sporadically and often. Constant flickering may indicate 
  a  very  busy  network  or  a  problem  somewhere  on  the  network  that  is 
  worth investigating.
 • Speed light: this LED indicates that the interface is connected at a certain 
  speed. This feature is normally found on Ethernet NICs that operate at 
  10Mbps/100Mbps and then only on certain cards.
                   AN EXPANSION NIC