Specifications

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Catalyst 2970 Switch Software Configuration Guide
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Chapter 11 Configuring VLANs
Configuring Extended-Range VLANs
• 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 12-11. You
should save this configuration to the startup configuration so that the switch boots up in VTP
transparent mode. Otherwise, you lose the extended-range VLAN configuration if the switch resets.
• 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 (128) 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 15, “Configuring MSTP.”
• Although the switch supports a total of 1005 (normal-range and extended-range) VLANs, the
number of configured features affects the use of the switch hardware. If you try to create an
extended-range VLAN and there are not enough hardware resources available, an error message is
generated, and the extended-range VLAN is rejected.
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 11-2) and
the MTU size and RSPAN configuration are the only parameters 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.
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 VLAN commands appear in the CLI help in
config-vlan mode, only the mtu mtu-size and remote-span
commands are supported for extended-range VLANs.