Hi ,
The new internal VLAN allocation feature simplifies VLAN management by providing greater flexibility in assigning both "internal" and "customer" VLANs. Traditionally, internal VLANs have been allocated for WAN interfaces, routed interfaces, and certain other features starting from VLAN 1006 (by default); when allocated, these internal VLANs are not available for customer VLAN assignment. The new internal VLAN allocation feature allows internal VLAN allocation to be assigned in descending order, beginning with VLAN ID 4096 rather than ascending from VLAN ID 1006. This allows customers to assign VLAN IDs in an ascending fashion without internal VLAN ID restrictions in the middle of the ID range.
The following information applies to VLAN ranges:
?Layer 3 LAN ports, WAN interfaces and subinterfaces, and some software features use internal VLANs in the extended range. You cannot use an extended range VLAN that has been allocated for internal use.
?To display the VLANs used internally, enter the show vlan internal usage command. With earlier releases, enter the show vlan internal usage and show cwan vlans commands.
?You can configure ascending internal VLAN allocation (from 1006 and up) or descending internal VLAN allocation (from 4094 and down).
?Switches running the Catalyst operating system do not support configuration of VLANs 1006-1024. If you configure VLANs 1006-1024, ensure that the VLANs do not extend to any switches running Catalyst software.
?You must enable the extended system ID to use extended range VLANs (see the "Understanding the Bridge ID" section).
http://www.cisco.com/en/US/products/hw/switches/ps708/prod_bulletin09186a00801352e9.html
Cheers :)
satish
