Types of VLANs
1-2
Virtual Local Area Networks
Figure 1-1
Example of a VLAN
In this example, the Sales and Finance workstations have been placed on two separate VLANs. In
a plain Ethernet environment, the entire network is a broadcast domain, and the SmartSwitches
follow the IEEE 802.1D bridging specification to send data between stations. A broadcast or
multicast transmission from a Sales workstation in Building One would propagate to all the switch
ports on SmartSwitch A, cross the high speed link to SmartSwitch B, and then propagated out all
switch ports on SmartSwitch B. The SmartSwitches treat each port as being equivalent to any other
port, and have no understanding of the departmental memberships of each workstation.
In a VLAN environment, each SmartSwitch understands that certain individual ports or frames are
members of separate workgroups. In this environment, a broadcast or multicast data transmission
from one of the Sales stations in Building One would reach SmartSwitch A, be sent to the ports
connected to other local members of the Sales VLAN, cross the high speed link to SmartSwitch B,
and then be sent to any other ports and workstations on SmartSwitch B that are members of the
Sales VLAN.
1.2
TYPES OF VLANs
There are a number of different strategies for creating Virtual Local Area Networks, each with
their own approaches to defining a station’s membership in a particular VLAN.
1
S
S
F
F
A
6
S
S
S
F
F
B
7
8
9
10
Building One
Building Two
SmartSwitch
SmartSwitch
trunk
2263-01
S
Member of Sales Network
Member of Finance Network
S
F
