Cisco CCNA Basics VI: Introduction to Extended VLANs

Today I am going to talk about the extended VLAN. Extended VLANs have the range of 1006 to 4094. Extended VLANs are always configured with the VTP transparent mode. These VLANs are configured basically on the service provider end or used by Service providers 

Make sure you know about extended VLANs, as 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. So, if you are using VTP v1 and VTP v2, a switch will be configured as 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.

STP is enabled by default on extended-range VLANs, but we 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.

Fig 1.1- Extended VLANs

Configuration on the switch with the extended VLAN 1007

RouteXP-SW3 # configure terminal

RouteXP-SW3(config) # vtp mode transparent << VTP mode Transparent >>

RouteXP-SW3(config) # vlan 1007 << Extended VLAN ID >>

RouteXP-SW3(config-vlan) # end

RouteXP-SW3 # copy running-config startup config