Saturday, 26 May 2012

Network Hardware

Networking hardware includes all computers, peripherals, interface cards and other equipment needed to perform data-processing and communications within the network.


  • File server
  • Workstation
  • Network Interface Cards
  • Concentrator/Hubs
  •  Repeater
  • Bridges
  •  Router
  • Switch

     1)      FILE SERVER

• A file server stands at the heart of most networks.
• Very fast computer
• Large amount of RAM and storage space,
• A fast network interface card.
• Network operating system software resides on this computer, along with any software applications and data files that need to be shared.


      2)      WORKSTATION

• User computers that are connected to a network are called workstations.
• configured with a network interface card, networking software, and the appropriate cables.
• do not necessarily storage capability; files can be saved on the file server.
• Almost any computer can serve as a network workstation.


• provides the physical connection between the network and the computer workstation.
• Major factor in determining the speed and performance of a network
• Most NICs are internal, with the card fitting into an expansion slot inside the computer.
• Some computers, such as Mac Classics, use external boxes which are attached to a serial port or a SCSI port.
• Laptop computers - built-in NIC or network cards that slip into a PCMCIA slot.
• The three most common network interface connections are
Ethernet cards
Local Talk connectors
Token Ring cards

                                 a)      Ethernet cards
• Ethernet cards contain connections for either coaxial or twisted pair cables (or both)
– BNC(Bayonet NeillConcelman) connection for coaxial cable
– RJ-45 connection for twisted pair,
• Some Ethernet cards also contain an AUI connector, used to attach coaxial, twisted pair or fiber optics cable to an Ethernet card.

b)      LocalTalk Connectors
• LocalTalk is Apple's built-in solution for networking Macintosh computers.
• utilizes a special adapter box and a cable that plugs into the printer port of a Macintosh.
• A major disadvantage of LocalTalk (.23 Mbps) is that it is slow in comparison to Ethernet (10 Mbps).

Ethernet VS. LocalTalk connection
Fast data transfer (10Mbps)
Slow data transfer (.23 Mbps)
Expensive – purchased separately
Requires computer slot
Available for most computers
Works only on Macintosh computers

c)      Token Ring Card
• Token Ring network cards look similar to Ethernet cards.
• One visible difference is the type of connector on the back end of the card.
• Generally have a nine pin DIN type connector to attach the card to the network cable.


       4)      HUB  &  5) SWITCH

Hub and Switch
·         Both devices contain ports to connect the devices together via networking cables and to facilitate communication between the devices, but they differ in how they transfer data.
  • ·         Transmit all data received to all nod connected to the hub.
  • ·         Regardless to which device the data being sent to
  • ·         Identifies the device on the network for which the data is intended and sends the data to that node only.
  • ·         A switch can connect Ethernet, token ring, Fibre Channel or other types of packet switched network segments together to form an internetwork.

     6)      REPEATERS   
To boost the signal with a device called a repeater. The repeater electrically amplifies the signal it receives and rebroadcasts it.
• Can be separate devices or they can be incorporated into a concentrator.
Used when the total length of your network cable exceeds the standards set for the type of cable being used.
• In a local area network using a star topology with unshielded twisted-pair cabling. The length limit for unshielded twisted-pair cable is 100 meters.
·         -The most common configuration is for each workstation to be connected by twisted-pair cable to a multi-port active concentrator.
·        - The concentrator amplifies all the signals that pass through it allowing for the total length of cable on the network to exceed the 100 meter limit.

      7)      BRIDGES
• A bridge monitors the information traffic on both sides of the network so that it can pass packets of information to the correct location the bridge manages the traffic to maintain optimum performance on both sides of the network
• It keeps information flowing on both sides of the network, but it does not allow unnecessary traffic through.
• can be used to connect different types of cabling, or physical topologies. They must be between networks with the same protocol.
• A network bridge connects multiple network segments.
• Bridges are similar to repeaters or network hubs, devices that connect network segments at the physical layer, however a bridge works by using bridging where traffic from one network is managed rather than simply rebroadcast to adjacent network segments.
• In Ethernet networks, the term "bridge" often referred to as a network switch in marketing literature.

        8)      ROUTER

translates information from one network to another; it is similar to a super-intelligent bridge.
• select the best path to route a message, based on the destination address and origin.
direct traffic to prevent head-on collisions, and is smart enough to know when to direct traffic along back roads and shortcuts.
• While bridges know the addresses of all computers on each side of the network, routers know the addresses of computers, bridges, and other routers on the network. Routers can even "listen" to the entire network to determine which sections are busiest - they can then redirect data around those sections until they clear up.
-It also determines the best route to send the data over the Internet.
-Routers can:
• Direct signal traffic efficiently
• Route messages between any two protocols
• Route messages between linear bus, star, and star-wired ring topologies
• Route messages across fiber optic, coaxial, and twisted-pair cabling


      9)      GATEWAY

• A network node equipped for interfacing with another network that uses different protocols.
A protocol translation/mapping gateway interconnects networks with different network protocol technologies by performing the required protocol conversions.

No comments:

Post a Comment