Reference Guide

Virtual LANs (VLAN) | 999
Use the show vlan command (Figure 52-3) in the EXEC privilege mode to view the configured VLANs.
Figure 52-3. show vlan Command Example
A VLAN is active only if the VLAN contains interfaces and those interfaces are operationally up. In
Figure 52-3, VLAN 1 is inactive because it contains the interfaces that are not active. The other VLANs
listed in the Figure 52-3 contain enabled interfaces and are active.
When you delete a VLAN (using the
no interface vlan vlan-id command), any interfaces assigned to that
VLAN are assigned to the Default VLAN as untagged interfaces.
Assign interfaces to a VLAN
Only interfaces in Layer 2 mode can be assigned to a VLAN using the tagged and untagged commands.
Use the
switchport command to place an interface in Layer 2 mode.
These Layer 2 interfaces can further be designated as tagged or untagged. For more information, refer to
the Interfaces chapter and Configure Layer 2 (Data Link) Mode. When an interface is placed in Layer 2
mode by the
switchport command, the interface is automatically designated untagged and placed in the
Default VLAN.
To view which interfaces are tagged or untagged and to which VLAN they belong, use the
show vlan
command. For example, Figure 52-3 shows that six VLANs are configured, and two interfaces are
assigned to VLAN 2. The Q column in the
show vlan command example notes whether the interface is
tagged (T) or untagged (U). For more information on this command, see the command statement in the
Layer 2 chapter of the FTOS Command Reference.
To view just the interfaces that are in Layer 2 mode, enter the
show interfaces switchport command in the
EXEC privilege mode or EXEC mode.
Note: In a VLAN, the shutdown command stops Layer 3 (routed) traffic only. Layer 2 traffic continues to
pass through the VLAN. If the VLAN is not a routed VLAN (that is, configured with an IP address), the
shutdown command has no affect on VLAN traffic.
FTOS#show vlan
Codes: * - Default VLAN, G - GVRP VLANs
NUM Status Q Ports
* 1 Inactive U So 9/4-11
2 Active U Gi 0/1,18
3 Active U Gi 0/2,19
4 Active T Gi 0/3,20
5 Active U Po 1
6 Active U Gi 0/12
U So 9/0
FTOS#