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| Local Area Networks |
The
local area networks (LANs) are distinguished from other types of data
networks in that they are optimized for a moderate-size geographic
area such as a single office building, a warehouse or a campus. The
nature of a LAN determined primarily by three factors: transmission
medium, topology and medium access control protocol.
LAN Topology
Common
topologies used for LAN are:
- Ring
- Bus
- Tree
- Star
Ring topology:
In the ring topology, the network consists of a set
of repeaters joined by point-to-point linked in closed loop. The
repeater is capable of receiving data on one link and transmitting
it, bit by bit, on the other link a as fast as it is receives, with
no buffering at the repeater. The links are unidirectional; that is,
data are transmitted in one direction only, and all oriented in same
way. Thus data circulate around the ring in one direction.
Bus and Tree topologies:
Both bus and tree
topologies are characterized by the use of a multi-point medium. With
the bus topology, all stations attach through appropriate
interfacing hardware, directly to a linear transmission medium or
bus. A transmission from any station propagates the length of the
medium in both directions and can be received by all other stations.
In tree topology, the transmission medium is a
branching cable with no closed loops. The free layout begins at a
point known as a head-end, one or more cables start at the head-end,
and each of these may have branches, the branches in turn any have
additional branches to allow quite complex layouts. Again, a
transmission from any station propagates throughout the medium can be
received by all other stations, and is absorbed at the endpoints.
The transmission is in the form of packets
containing addresses and user data. Each station monitors the medium
and copies packets addressed to itself. Because all stations share a
common transmission link, only one station can successfully transmit
at a time, and some form of medium access control technique is needed
to regulate access.
Star topology:
In the star topology,
each station is directly connected to a common central switch. The
star topology is also employed for implementing a packet-broadcasting
LAN. In this case, each station attaches to a central node, referred
to as the star coupler via two point-to-point links, one for
transmission in each direction. A transmission from any one station
enters the central node and is retransmitted on all of the outgoing
links. A transmission from any station is received by all other
stations, and only one station at a time may successfully transmit.
Thus the medium access control techniques used for the packet star
topology are the same as for bus and tree.
Related Post:
If your computer is part of a Local Area Network (LAN), wired or wireless you can use Windows 7 to share your locally attached printer with other computers on the network. You can do this when you install a new printer or after it has already to be install.
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