Beginning with Cisco NX-OS Release 5.1(1) ,
you can configure a VLAN without actually creating the VLAN. This procedure is
used for IGMP snooping, VTP, and other configurations.
VLANs are numbered
from 1 to 4094 for each VDC. All ports that you have configured as switch ports
belong to the default VLAN when you first bring up the switch as a Layer 2
device. The default VLAN (VLAN1) uses only default values, and you cannot
create, delete, or suspend activity in the default VLAN.
You create a VLAN by
assigning a number to it; you can delete VLANs and move them from the active
operational state to the suspended operational state. If you attempt to create
a VLAN with an existing VLAN ID, the device goes into the VLAN submode but does
not create the same VLAN again.
Newly created VLANs
remain unused until Layer 2 ports are assigned to the specific VLAN. All the
ports are assigned to VLAN1 by default.
Depending on the
range of the VLAN, you can configure the following parameters for VLANs (except
the default VLAN):
Shutdown or not
with Cisco NX-OS Release 6.1(1), you can configure VLAN long-names of up to 128
characters. To configure VLAN long-names, VTP must be in transparent or in off
mode. If VTP is in client or server mode, the VLAN long-name feature cannot be
enabled. For more details about VTP, see the
7000 Series NX-OS Interfaces Configuration Guide for information on
configuring ports as VLAN access or trunk ports and assigning ports to VLANs.
When you delete a
specified VLAN, the ports associated to that VLAN become inactive and no
traffic flows. When you delete a specified VLAN from a trunk port, only that
VLAN is shut down and traffic continues to flow on all the other VLANs through
the trunk port.
However, the system
retains all the VLAN-to-port mapping for that VLAN, and when you reenable or
re-create, that specified VLAN, the system automatically reinstates all the
original ports to that VLAN. The static MAC addresses and aging time for that
VLAN are not restored when the VLAN is reenabled.
NX-OS Release 5.1, commands entered in the VLAN configuration submode are
immediately executed. Beginning with Cisco Release NX-OS 5.1 for Nexus 7000
Series devices, you must exit the VLAN configuration submode for configuration
changes to take effect.