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Configuring VLANs
Information About Configuring VLANs
VLANs
A VLAN is a switched network that is logically segmented by function, project team, or application, without regard to the
physical locations of the users. VLANs have the same attributes as physical LANs, but you can group end stations even
if they are not physically located on the same LAN segment. Any switch port can belong to a VLAN, and unicast,
broadcast, and multicast packets are forwarded and flooded only to end stations in the VLAN. Each VLAN is considered
a logical network, and packets destined for stations that do not belong to the VLAN must be forwarded through a router
or a switch supporting fallback bridging, as shown in Figure 29 on page 271. Because a VLAN is considered a separate
logical network, it contains its own bridge Management Information Base (MIB) information and can support its own
implementation of spanning tree. See Configuring STP, page 315
Note: Before you create VLANs, you must decide whether to use VLAN Trunking Protocol (VTP) to maintain global VLAN
configuration for your network.
Figure 29 VLANs as Logically Defined Networks
VLANs are often associated with IP subnetworks. For example, all the end stations in a particular IP subnet belong to the
same VLAN. Interface VLAN membership on the switch is assigned manually on an interface-by-interface basis. When
you assign switch interfaces to VLANs by using this method, it is known as interface-based, or static, VLAN membership.
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