Chapter 10: Virtual LANs (VLANs) LANCOM Reference Manual LCOS 3.50
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Virtual LANs (VLANs)
But this task is very burdensome to realize by hardware changes, or even not
at all, because e.g. only one single central cabling exists in the office building.
Virtual LANs enable to perform this task in a very smart way. Also when
departments or companies change at a later time inside of the building, the
network structure can be easily adjusted.
All network users in this example use the central Ethernet, which is, like the
connected devices, supervised by a service provider. Company A has three
departments on two floors. The sales department can communicate with the
administration department via VLAN ID 3, the accounts department with the
administration via VLAN ID 5. The networks of accounts department and sales
do not see each other. Company B is also shielded by VLAN ID 11 against all
other networks, only the service provider can access all devices for mainte-
nance purposes.
central network cabling
VLAN ID=3 VLAN ID=5
Company
A, sales
VLAN ID=11VLAN ID=3, 5
Company A,
accounts dep.
Comp. A, administrat. Comp. B
VLAN ID=3, 5, 11