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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 14 Configuring VLANs
Configuring Extended-Range VLANs
• STP is enabled by default on extended-range VLANs, but you can disable it by using the no
spanning-tree vlan vlan-id global configuration command. When the maximum number of
spanning-tree instances (64) are on the switch, spanning tree is disabled on any newly created
VLANs. If the number of VLANs on the switch exceeds the maximum number of 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 STP instance. For more information about MSTP, see
Chapter 12, “Configuring RSTP and MSTP.”
Creating an Extended-Range VLAN
You create an extended-range VLAN in global configuration mode by entering the vlan global
configuration command with a VLAN ID from 1006 to 4094. This command accesses the config-vlan
mode. The extended-range VLAN has the default Ethernet VLAN characteristics (see Table 14-2) and
the MTU size is the only parameter you can change. Refer to the description of the vlan global
configuration command in the command reference for defaults of all parameters. If you enter an
extended-range VLAN ID when the switch is not in VTP transparent mode, an error message is
generated when you exit from config-vlan mode, and the extended-range VLAN is not created.
Extended-range VLANs are not saved in the VLAN database; they are saved in the switch running
configuration file. You can save the extended-range VLAN configuration in the switch startup
configuration file by using the copy running-config startup-config privileged EXEC command.
Note Before you create an extended-range VLAN, you can verify that the VLAN ID is not used internally by
entering the show vlan internal usage privileged EXEC command. If the VLAN ID is used internally
and you want to free it up, go to the “Displaying VLANs” section on page 14-14 before creating the
extended-range VLAN.
Beginning in privileged EXEC mode, follow these steps to create an extended-range VLAN:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
vtp mode transparent Configure the switch for VTP transparent mode, disabling VTP.
Step 3
vlan vlan-id Enter an extended-range VLAN ID and enter config-vlan mode. The
range is 1006 to 4094.
Step 4
mtu mtu-size (Optional) Modify the VLAN by changing the MTU size.
Note Although all commands appear in the CLI help in config-vlan
mode, only the mtu mtu-size command is supported for
extended-range VLANs.
Step 5
end Return to privileged EXEC mode.
Step 6
show vlan id vlan-id Verify that the VLAN has been created.
Step 7
copy running-config startup config Save your entries in the switch startup configuration file. To save
extended-range VLAN configurations, you need to save the VTP
transparent mode configuration and the extended-range VLAN
configuration in the switch startup configuration file. Otherwise, if the
switch resets, it will default to VTP server mode, and the extended-range
VLAN IDs will not be saved.