Full form: Virtual Local Area Network
Also known as: Virtual LAN, Virtual Local Area Network
Quick Definition
A logical segmentation of a switch network into separate broadcast domains.
A VLAN groups switch ports into separate logical networks, each with its own broadcast domain, regardless of physical location. Devices in different VLANs cannot communicate without a Layer 3 device (router or Layer 3 switch). VLANs improve security by isolating traffic, reduce broadcast overhead, and allow logical network design independent of physical cabling. VLAN tags (IEEE 802.1Q) are added to Ethernet frames on trunk links to identify which VLAN a frame belongs to.
vlan 10 name SALES interface GigabitEthernet0/1 switchport mode access switchport access vlan 10
VLAN 1 is the default VLAN and cannot be deleted. It is also the default native VLAN on trunk links. Best practice is to change the native VLAN from 1 and not use VLAN 1 for user traffic.
The set of all devices that receive a Layer 2 broadcast frame.
A virtual Layer 3 interface on a switch used to route between VLANs.
A switch port configured to carry traffic for multiple VLANs using 802.1Q tags.
A switch port assigned to a single VLAN, connecting end devices such as PCs and printers.
The VLAN whose frames pass untagged on a trunk link — VLAN 1 by default.
A dedicated VLAN for IP phone traffic, configured on an access port alongside a data VLAN.
A Cisco proprietary protocol that automatically negotiates trunk formation between switches.
A VLAN groups switch ports into separate logical networks, each with its own broadcast domain, regardless of physical location. Devices in different VLANs cannot communicate without a Layer 3 device (router or Layer 3 switch). VLANs improve security by isolating traffic, reduce broadcast overhead, and allow logical network design independent of physical cabling. VLAN tags (IEEE 802.1Q) are added to Ethernet frames on trunk links to identify which VLAN a frame belongs to.
VLAN 1 is the default VLAN and cannot be deleted. It is also the default native VLAN on trunk links. Best practice is to change the native VLAN from 1 and not use VLAN 1 for user traffic.
VLAN falls under the VLANs domain of the 200-301 exam. Understanding it in context with related terms like trunk-port and access-port is essential for answering scenario-based questions correctly.