Standard VLANs 1 – 1005 | Extended VLANs 1006 – 4094 | Internal VLANs
Range 1 – 1005
Default Ethernet Access VLAN, cannot be deleted and default 802.1q Native VLAN.
Used for exchange in control plane for protocols, that’s why you cannot delete VLAN 1.
For best practices it should not be used for actual port assignments.
If you enable VTP pruning then, this VLAN cannot be pruned automatically; but using switchport trunk allowed list command you can prune this VLAN.
By default, all interfaces are members of this VLAN.
Vlan 1002 – 1005
Default legacy Token Ring / FDDI VLANs
Cannot be deleted
VLAN 1006 – 4094
Can be used in one of two cases à Transparent Mode | VTP Version 3
Some VLANs in extended range are reserved for “internal” usage.
There is no standardized range for internal VLANs, it depend on platform.
This range is reserved for internal applications. If you want a routed interface on Layer 3 switch, we normally use no switchport command. Then assign IP address to that interface.
When you configure this, actually switch creates Switched Virtual Interface (SVI) using one of the VLAN from the range of internal VLANs. To verify which internal VLAN is assigned to SVI use show vlan internal usage command.
Before configuring Layer 3 interface, we get below output for show vlan internal usage command. Currently there is no internal VLAN being used.
Following output shows, interface f0/10 is configured as a layer 3 port.
After f0/10 interface configured as layer 3 interface, switch internally creates VLAN 1006 (as below snapshot). Now interface f0/10 is member of VLAN 1006 and this VLAN ID used is from the range of extended VLAN.
It’s a switch’s default behavior to use internal VLANs for these Layer 3 interfaces. Now VLAN 1006 can’t be configured as this VLAN is already used by switch for internal VLAN.