15-6
Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 15 Configuring VLANs
Configuring Normal-Range VLANs
are several adjacent switches that all have run out of spanning-tree instances. You can prevent this
possibility by setting allowed lists on the trunk ports of switches that have used up their allocation
of spanning-tree instances.
If the number of VLANs on the switch exceeds the number of supported spanning-tree instances,
we recommend that you configure the IEEE 802.1s Multiple STP (MSTP) on your switch to map
multiple VLANs to a single spanning-tree instance. For more information about MSTP, see
Chapter 19, “Configuring MSTP.”
VLAN Configuration Mode Options
You can configure normal-range VLANs (with VLAN IDs 1 to 1005) by using these two configuration
modes:
•
VLAN Configuration in config-vlan Mode, page 15-6
You access config-vlan mode by entering the
vlan
vlan-id
global configuration command.
•
VLAN Configuration in VLAN Database Configuration Mode, page 15-6
You access VLAN database configuration mode by entering the
vlan
database
privileged EXEC
command.
VLAN Configuration in config-vlan Mode
To access config-vlan mode, enter the
vlan
global configuration command with a VLAN ID. Enter a new
VLAN ID to create a VLAN, or enter an existing VLAN ID to modify that VLAN. You can use the
default VLAN configuration (
Table 15-2
) or enter multiple commands to configure the VLAN. For more
information about commands available in this mode, see the
vlan
global configuration command
description in the command reference
for this release. When you have finished the configuration, you
must exit config-vlan mode for the configuration to take effect. To display the VLAN configuration,
enter the
show vlan
privileged EXEC command.
You must use this config-vlan mode when creating extended-range VLANs (VLAN IDs greater than
1005). See the
“Configuring Extended-Range VLANs” section on page 15-11
.
VLAN Configuration in VLAN Database Configuration Mode
To access VLAN database configuration mode, enter the
vlan database
privileged EXEC command.
Then enter the
vlan
command with a new VLAN ID to create a VLAN, or enter an existing VLAN ID
to modify the VLAN. You can use the default VLAN configuration (
Table 15-2
) or enter multiple
commands to configure the VLAN. For more information about keywords available in this mode, see the
vlan
VLAN database configuration command description in the command reference for this release.
When you have finished the configuration, you must enter
apply
or
exit
for the configuration to take
effect. When you enter the
exit
command, it applies all commands and updates the VLAN database. VTP
messages are sent to other switches in the VTP domain, and the privileged EXEC mode prompt appears.
Saving VLAN Configuration
The configurations of VLAN IDs 1 to 1005 are always saved in the VLAN database (vlan.dat file). If the
VTP mode is transparent, they are also saved in the switch running configuration file. You can enter the
copy running-config startup-config
privileged EXEC command to save the configuration in the startup
configuration file. To display the VLAN configuration, enter the
show vlan
privileged EXEC command.