Hands-On Lab: Configuring Extended VLANs on Cisco Catalyst Switches

Lab Objective

Attempt to create an extended-range VLAN while VTP version 1 is active and observe the failure, then configure VTP version 3 to support extended VLANs, successfully create one, and verify it functions normally.

Lab Purpose

The standard VLAN range (1-1005) is often insufficient in very large environments such as service provider or large campus networks, which is why the extended range (1006-4094) exists. However, older VTP versions cannot propagate extended VLANs at all, a limitation that causes confusing failures if not understood.

Lab Topology

Switch1 (standalone switch for this lab,
         VTP domain CorpNet)

Task 1: Attempt to Create an Extended VLAN Under VTP Version 1

With Switch1 in VTP server mode using VTP version 1 (the default), attempt to create VLAN 2000 and observe the result.

Task 2: Upgrade to VTP Version 3

Change Switch1's VTP version to 3, which adds support for extended-range VLANs in server mode.

Task 3: Create the Extended VLAN

Create VLAN 2000 named LargeSiteVLAN.

Task 4: Verify the Extended VLAN Functions Normally

Assign a port to VLAN 2000 and confirm it behaves identically to any standard-range VLAN.

Solution and Verification

Switch1(config)# vtp mode server
Switch1(config)# vtp version

-- (default is version 1 unless previously changed)

Switch1(config)# vlan 2000

% VTP does not support extended VLANs.
% Failed to create VLANs 2000
-- VTP version 1 (and 2) cannot propagate or
-- even locally support VLANs above 1005 in
-- server mode

Switch1(config)# vtp version 3

Switch1# show vtp status | include Version

VTP version running    : 3

Switch1(config)# vlan 2000
Switch1(config-vlan)# name LargeSiteVLAN
Switch1(config-vlan)# exit

Switch1# show vlan brief | include 2000

2000 LargeSiteVLAN  active

Switch1(config)# interface gigabitethernet1/0/10
Switch1(config-if)# switchport mode access
Switch1(config-if)# switchport access vlan 2000

Switch1# show vlan brief | include 2000
2000 LargeSiteVLAN  active    Gi1/0/10
-- Functions exactly like any standard-range
-- VLAN once created

Key Takeaway

Extended-range VLANs (1006-4094) require VTP version 3 to be created and properly propagated through a VTP server — attempting to create one under VTP version 1 or 2 fails outright with an explicit error, a detail that must be checked first whenever an extended VLAN unexpectedly cannot be configured.