16-12
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
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Chapter 16 Configuring VLANs
Configuring Extended-Range VLANs
Extended-range VLAN configurations are not stored in the VLAN database. Because VTP mode is
transparent, they are stored in the switch running configuration file. You can save the configuration in
the startup configuration file by using the copy running-config startup-config privileged EXEC
command.
Note Although the switch supports 4094 VLAN IDs, see the “Supported VLANs” section on page 16-2 for
the actual number of VLANs supported.
This section includes this information about extended-range VLANs:
• Default VLAN Configuration, page 16-12
• Extended-Range VLAN Configuration Guidelines, page 16-12
• Creating an Extended-Range VLAN, page 16-13
• Displaying VLANs, page 16-14
Default VLAN Configuration
See Table 16-2 on page 16-8 for the default configuration for Ethernet VLANs. You can change only the
MTU size on extended-range VLANs; all other characteristics must remain at the default state.
Extended-Range VLAN Configuration Guidelines
Follow these guidelines when creating extended-range VLANs:
• To add an extended-range VLAN, you must use the vlan vlan-id global configuration command and
access config-vlan mode. You cannot add extended-range VLANs in VLAN database configuration
mode (accessed by entering the vlan database privileged EXEC command).
• VLAN IDs in the extended range are not saved in the VLAN database and are not recognized by
VTP.
• You cannot include extended-range VLANs in the pruning eligible range.
• 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.”
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