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Extended-Range VLAN Configuration Guidelines

VTP 3 only supports extended-range VLANs. Extended-range VLANs are VLANs with IDs from 1006 to

4094.

Follow these guidelines when creating extended-range VLANs:

•

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. 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. 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.

•

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

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 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 the

internal VLAN, and then create the extended-range VLAN and re-enable the port, which then uses

another VLAN as its internal VLAN.

•

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.