Lan Network

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ESSAY ON LAN NETWORK

• DEFINITION OF LAN

• HARDWARE COMPONENTS OF LAN

• SOFTWARE COMPONENTS OF LAN

• DESCRIPTION OF EACH COMPONENT

• DIFFERENT TOPOLOGY IN LAN

• ADVANTAGES AND DISADVANTAGES OF EACH TOPOLOGY

LAN :

The typical definition of Local Area Network (LAN) is "two or more connected stations (PCs, servers, computer…) in the same limited area, sharing data and peripheral devices, and operating .The most popular LANs include 10 Mbps & 100 Mbps Ethernet, 4 Mbps & 16 Mbps Token Ring.

HARDWARE COMPONENTS OF LAN NETWORK
The hardware components of a LAN consist of:

* PCs/workstations and servers
* Network Interface Card (NIC)
* Cabling and connectors,
* Hub, concentrator, and more complicated network devices such as Bridge, LAN Switch and Router

SOFTWARE COMPONENTS OF LAN NETWORK
The software components of a LAN can be grouped into two categories: Inside PCs/workstations and servers
Inside network devices (Hub/Bridge/LAN Switch/Router)

HUB
A Hub is a central device used on star network topology that repeats or amplifies signals, allowing the network to be lengthened or expanded with additional stations. For example, an Ethernet hub normally has 8 or 12 or 16 RJ-45 ports, each port can be connected to a PC or workstation or server. Also, the hub’s BNC port can be connected to a coaxial cable to lengthen the network.

BRIDGE
A Bridge is a device used to connect two or more LANs. It operates at the Media Access Control Layer (layer 2), checking and forwarding data packets between different LANs.

LAN SWITCH
A LAN Switch is a device using switching hardware to speed-up the checking and forwarding of data packets between LANs. LAN Switch is functionally like a bridge, but its speed and performance is faster and better than a bridge.

ROUTER
A Router is a device that operates at the network layer (layer 3), routing data between similar or dissimilar networks. A router is more powerful than a bridge or LAN Switch because the router checks the network protocols and addresses (for example, IP or IPX).

NETWORK INTERFACE CARD ( NIC )
A Network Interface Card (NIC) is an add-on adapter card that is installed to the PCI or ISA slot on the PC’s motherboard. The NIC sorts data on the computer into bundles and transmits them to another computer while allowing the user to access the data within the bundle simultaneously. The most common NIC used today is the 10Base-T Ethernet card that is connected to an Ethernet hub.

HUB
All Ethernet 10Base-T networks are connected with an Ethernet hub. The hub manages the traffic that passes between computers on a network and is connected to all computers that are part of the network.

LAN TOPOLOGIES

LAN topologies define the manner in which network devices
are organized. Four common LAN topologies exist
• bus,
• ring,
• Star
• tree.

These topologies are logical architectures, but the actual
devices need not be physically organized in these configurations. Logical busand ring topologies, for example, are commonly organized physically as a star.

BUS TOPOLOGY
A bus topology is a linear LAN architecture in which
transmissions from network stations propagate the length of the medium and are received by all other stations.

Advantages of a Linear Bus Topology
• Easy to connect a computer or peripheral to a linear
bus.
• Requires less cable length than a star topology.

Disadvantages of a Linear Bus Topology
• Entire network shuts down if there is a break in the
main cable.
• Terminators are required at both ends of the backboned
cables.
• It is difficult to identify the problem if the entire
network shuts down.
• Not good as a stand-alone solution in a large
building.

RING TOPOLOGY :
A ring topology is a LAN architecture that consists of a series of devices connected to one another by unidirectional transmission links to form a single closed loop.

STAR...
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