QUE:- What is VLAN? Explain in Detail OR Write a Short note on VLAN
ANS:-
Figure shows the switched LAN
divided into VLANs.
Ø The idea of VLAN
technology is to divide a LAN into logical, instead of physical, segments. A
LAN can be divided into several logical LANs called VLANs.
Ø Each VLAN is a
work group in the organization.
Ø If a person
moves from one group to another, there is no need to change the physical
configuration.
Ø The group
membership in VLANs is defined by software, not hardware.
Ø Any station can
be logically moved to another VLAN.
Ø All members
belonging to a VLAN can receive broadcast messages sent to that particular VLAN.
Ø This means if a
station moves from VLAN 1 to VLAN 2, it receives broadcast messages sent to
VLAN 2, but no longer receives broadcast messages sent to VLAN
1.
Ø VLAN technology
even allows the grouping of stations connected to different switches in a VLAN.
Following
Figure shows a backbone local area network with three switches and two VLANs.
Ø The stations in
a VLAN communicate with one another as though they
belonged to a physical
segment.
Advantages
There are several advantages to
using VLANs.
1)
Cost and Time
Reduction
Ø VLANs can reduce
the transmission cost of stations going from one group to another.
Ø Instead of
physically moving one station to another segment or even to another switch, it
is much easier and quicker to move it by using software.
2)
Creating Virtual
Work Groups
Ø VLANs can be
used to create virtual work groups. For example, in a campus environment,
professors working on the same project can send broadcast messages to one another
without the necessity of belonging to the same department.
Ø This can reduce traffic
if the multicasting capability of IP was previously used.
3)
Security
Ø VLANs provide an
extra measure of security.
Ø
People
belonging to the same group can send broadcast messages with the guaranteed
assurance that users in other groups will not receive these messages.
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