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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 16 Configuring VLANs
Configuring Extended-Range VLANs
• The switch must be in VTP transparent mode when you create extended-range VLANs. If VTP mode
is server or client, an error message is generated, and the extended-range VLAN is rejected.
• You can set the VTP mode to transparent in global configuration mode or in VLAN database
configuration mode. See the
“Disabling VTP (VTP Transparent Mode)” section on page 17-12. You
should save this configuration to the startup configuration so that the switch will boot up in VTP
transparent mode. Otherwise, you will lose extended-range VLAN configuration if the switch resets.
• VLANs in the extended range are not supported by VQP. They cannot be configured by VMPS.
• 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 14, “Configuring 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 16-2), and
the MTU size is the only parameter you can change. See 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.
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.