Cisco Catalyst 3750-E Software Configuration Manual page 423

Chapter 13 Configuring VLANs
Extended-Range VLAN Configuration Guidelines
Follow these guidelines when creating extended-range VLANs:
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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. The extended-range VLAN has the default
Ethernet VLAN characteristics (see
configuration are the only parameters you can change. See the description of the vlan global
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VLAN IDs in the extended range are not saved in the VLAN database and are not recognized by
VTP unless the switch is running VTP version 3.
You cannot include extended-range VLANs in the pruning eligible range.
In VTP version 1 and 2, a 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. VTP version 3 supports extended VLANs in server and transparent modes.
For VTP version 1 or 2, you can set the VTP mode to transparent in global configuration mode. See
the "Configuring VTP Mode" section on page
startup configuration so that the switch boots up in VTP transparent mode. Otherwise, you lose the
extended-range VLAN configuration if the switch resets. If you create extended-range VLANs in
VTP version 3, you cannot convert to VTP version 1 or 2.
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 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 spanning-tree instance. For more information about MSTP, see
Chapter 19, "Configuring MSTP."
Each routed port on the switch creates an internal VLAN for its use. These internal VLANs use
extended-range VLAN numbers, and the internal VLAN ID cannot be used for an extended-range
VLAN. If you try to create an extended-range VLAN with a VLAN ID that is already allocated as
an internal VLAN, an error message is generated, and the command is rejected.
Because internal VLAN IDs are in the lower part of the extended range, we recommend that you
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create extended-range VLANs beginning from the highest number (4094) and moving to the
lowest (1006) to reduce the possibility of using an internal VLAN ID.
Before configuring extended-range VLANs, enter the show vlan internal usage privileged
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EXEC command to see which VLANs have been allocated as internal VLANs.
If necessary, you can shut down the routed port assigned to the internal VLAN, which frees up
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the internal VLAN, and then create the extended-range VLAN and re-enable the port, which
then uses another VLAN as its internal VLAN. See the
with an Internal VLAN ID" section on page
Although the switch or switch stack supports a total of 1005 (normal-range and extended-range)
VLANs, the number of routed ports, SVIs, and other 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.
In a switch stack, the whole stack uses the same running configuration and saved configuration, and
extended-range VLAN information is shared across the stack.
14-11. You should save this configuration to the
13-13.
Table 13-2) and the MTU size, private VLAN, and RSPAN
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
Configuring Extended-Range VLANs
"Creating an Extended-Range VLAN
13-11