Cisco Cisco IOS Software Release 12.4(15)T

Before you configure an extended VLAN ID, you should understand the following concepts:

Before Cisco IOS Release 12.4(15)T, users were permitted to configure VLANs numbered from 2 to 
1001. The remaining VLANs (numbered from 1006 to 4094) were reserved for use as internal VLANs 
configured by applications. Beginning with Cisco IOS Release 12.4(15)T, all VLAN numbers except those 
reserved for default and reserved VLANs are available for user configuration. The result is that users and 
applications share the VLAN number space from 1006 to 4094. To manage this number space effectively, 
follow these guidelines:

Internal VLAN numbers begin with 1006 and use the next higher number for each additional VLAN.

Users should configure extended VLAN ID numbers beginning with 4094 and use the next lower number 
for each additional VLAN. 

A first-come, first-served policy governs the allocation of numbers to internal VLANs and 
user-configured VLANs in the extended VLAN number space.

During system bootup, internal VLANs required for the features in the startup-configuration file are 
allocated numbers first, followed by user-configured VLANs in the startup configuration. 

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 you configure a VLAN number that matches the number of an existing internal VLAN, an error 
message appears and the extended VLAN configuration is denied. 

To configure an extended VLAN with a number that is assigned to an internal VLAN, follow these steps:

Shut down the port assigned to the internal VLAN, freeing up the assigned VLAN number.

Create the extended-range VLAN with the desired VLAN number.

Reenable the port, which then uses a different VLAN number for its internal VLAN. See the 

 section for details.

 shows the default configuration for Ethernet VLANs. 

The router supports Ethernet interfaces exclusively. Because Fiber Distributed Data Interface (FDDI) 
and Token Ring VLANs are not locally supported, you only configure FDDI and Token Ring 
media-specific characteristics for VTP global advertisements to other devices.