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16-5
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 16 Configuring VLANs
Configuring Normal-Range VLANs
• Normal-Range VLAN Configuration Guidelines, page 16-5
• VLAN Configuration Mode Options, page 16-6
• Saving VLAN Configuration, page 16-6
• Default Ethernet VLAN Configuration, page 16-7
• Creating or Modifying an Ethernet VLAN, page 16-8
• Deleting a VLAN, page 16-9
• Assigning Static-Access Ports to a VLAN, page 16-10
Token Ring VLANs
Although the switch does not support Token Ring connections, a remote device such as a Catalyst 5000
series switch with Token Ring connections could be managed from one of the supported switches.
Switches running VTP version 2 advertise information about these Token Ring VLANs:
• Token Ring TrBRF VLANs
• Token Ring TrCRF VLANs
For more information on configuring Token Ring VLANs, see the Catalyst 5000 Series Software
Configuration Guide.
Normal-Range VLAN Configuration Guidelines
Follow these guidelines when creating and modifying normal-range VLANs in your network:
• See the “Supported VLANs” section on page 16-2 for the maximum number of supported VLANs
per switch model. On a switch supporting 250 VLANs, if VTP reports that there are 250 active
VLANs, four of the active VLANs (1002 to 1005) are reserved for Token Ring and FDDI.
• Normal-range VLANs are identified with a number between 1 and 1001. VLAN numbers 1002
through 1005 are reserved for Token Ring and FDDI VLANs.
• VLAN configuration for VLANs 1 to 1005 are always saved in the VLAN database. If VTP mode
is transparent, VTP and VLAN configuration are also saved in the switch running configuration file.
• The switch also supports VLAN IDs 1006 through 4094 in VTP transparent mode (VTP disabled).
These are extended-range VLANs, and configuration options are limited. Extended-range VLANs
are not saved in the VLAN database. See the
“Configuring Extended-Range VLANs” section on
page 16-11.
• Before you can create a VLAN, the switch must be in VTP server mode or VTP transparent mode.
If the switch is a VTP server, you must define a VTP domain, or VTP will not function.
• The switch does not support Token Ring or FDDI media. The switch does not forward FDDI,
FDDI-Net, TrCRF, or TrBRF traffic, but it does propagate the VLAN configuration through
VTP.
• The switch supports 64 spanning-tree instances. If a switch has more active VLANs than supported
spanning-tree instances, spanning tree can be enabled on 64 VLANs and is disabled on the
remaining VLANs. If you have already used all available spanning-tree instances on a switch,
adding another VLAN anywhere in the VTP domain creates a VLAN on that switch that is not
running spanning tree. If you have the default allowed list on the trunk ports of that switch (which
is to allow all VLANs), the new VLAN is carried on all trunk ports. Depending on the topology of
the network, this could create a loop in the new VLAN that would not be broken, particularly if there