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LAN
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INTRODUCTION:
WHY WE NEED NETWORKING?
" As companies rely on applications like electronic
mail and database management for core business operations,
computer networking becomes increasingly more important.
" In today's business strategies taking a decision
within some seconds can result in a several changes this
could be impact for networking.
" So, in short "networking" is the one
guiding today's world in all areas.
WHAT IS LAN?
" A network is any collection of independent computers
that communicate with one another over a shared network
medium.
" LANs are networks usually confined to a geographic
area, such as a single building or a college campus.
" LANs can be small, linking as few as three computers,
but often link hundreds of computers used by thousands
of people.
" The development of standard networking protocols
and media has resulted in worldwide proliferation of LANs
throughout business and educational organizations.
LAN TOPOLOGIES:
" It refers to the way a network is laid out.
" It refers the physical or logical arrangements
of links in a network.
" The topology of a network is the geometric representation
of the relationship of all the links and linking devices(usually
nodes) to each other.
CATEGORIES OF TOPOLOGY:
1. MESH TOPOLOGY
2. STAR TOPOLOGY
3. TREE TOPOLOGY
4. BUS TOPOLOGY
5. RING TOPOLOGY
MESH TOPOLOGY:
" Every device has dedicated point-to point link to every
other device. " A fully connected mesh network has n(n-1)/2
physical channels to link 'n' devices.
ADVANTAGES:
1. Use of dedicated links eliminate traffic problem. 2.
Robust: if one link became unusable it can't incapacitate
the entire system. 3. Privacy or security. 4. Point -to-
point links make fault identification and isolation easy.
DISADVANTAGES:
1. More amount of cabling and i/o ports. 2. More expensive.
STAR TOPOLOGY:
STAR TOPOLOGY:
" each device has point-to-point link only to a central
controller(HUB). " The controller acts as a exchange
ADVANTAGES:
1. Less cabling is used it causes less expensive.
2. Easy to install and reconfigure.
3. Robustness
4. Easy fault identification and isolation can be made.
DISADVANTAGES:
If hub fails means then whole network is collapsed.
TREE TOPOLOGY:
" From a purely topologic viewpoint, this resembles
an interconnection of star networks
" In this individual peripheral nodes (i.e.leaves)
are required to transmit to and receive from one other
node only and are not required to act as repeaters or
regenerators.
" Unlike the star network, the function of the central
node may be distributed.
" However not every device plugs directly in central
hub.the majority of devices connected to a secondary hub
that in turn connected to central hub.
" Good example for tree topology is the cable tv
technology.
ADVANTAGES:
The addition of secondary hubs led's to more device can
be connected
It allows network to isolate and prioritize communication
from different computers.
BUS AND TREE TOPOLOGY:
BUS TOPOLOGY:
" A bus topology is multipoint. " One long cable act as
a backbone to link all the cables. " Using a "tap" and
"dropline" the link have been made. " Dropline is a connection
running between the device and main cable.
ADVANTAGES:
Ease of installation Less cabling is used.
DISADVANTAGES:
Difficult in reconfiguration and fault isolation. Difficult
to add new devices. A fault or break in the bus cable
stops all transmission. RING TOPOLOGY: A network topology
in which every node has exactly two branches connected
to it. Each device in the ring incorporates a repeater.
" A bus topology is multipoint.
" One long cable act as a backbone to link all the
cables.
" Using a "tap" and "dropline"
the link have been made.
" Dropline is a connection running between the device
and main cable.
ADVANTAGES:
Ease of installation
Less cabling is used.
DISADVANTAGES:
Difficult in reconfiguration and fault isolation.
Difficult to add new devices.
A fault or break in the bus cable stops all transmission.
RING TOPOLOGY:
A network topology in which every node has exactly two
branches connected to it.
Each device in the ring incorporates a repeater.
ADVANTAGES:
Easy to install
To add or delete a device requires moving only two connections.
Fault isolation is simplified.
DISADVANTAGES:
Unidirectional traffic.
In simple ring a break can disable the entire network.
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