Also known as: auxiliary VLAN
Quick Definition
A dedicated VLAN for IP phone traffic, configured on an access port alongside a data VLAN.
A voice VLAN is a separate VLAN configured on an access port to carry VoIP traffic from an IP phone. The access port connects to the IP phone, and the phone connects to the PC. The phone sends tagged frames on the voice VLAN and passes through untagged frames from the PC on the data VLAN. A port with both a data VLAN and a voice VLAN is sometimes called a multi-VLAN access port.
interface GigabitEthernet0/3 switchport mode access switchport access vlan 10 switchport voice vlan 20
When a voice VLAN is configured, the port should also enable QoS trust for DSCP or CoS markings: 'mls qos trust cos'. Without QoS, voice quality may degrade.
A logical segmentation of a switch network into separate broadcast domains.
A switch port assigned to a single VLAN, connecting end devices such as PCs and printers.
Mechanisms that prioritise certain types of network traffic to guarantee performance.
A 6-bit field in the IP header used to mark packets for QoS treatment.
A voice VLAN is a separate VLAN configured on an access port to carry VoIP traffic from an IP phone. The access port connects to the IP phone, and the phone connects to the PC. The phone sends tagged frames on the voice VLAN and passes through untagged frames from the PC on the data VLAN. A port with both a data VLAN and a voice VLAN is sometimes called a multi-VLAN access port.
When a voice VLAN is configured, the port should also enable QoS trust for DSCP or CoS markings: 'mls qos trust cos'. Without QoS, voice quality may degrade.
Voice VLAN falls under the VLANs domain of the 200-301 exam. Understanding it in context with related terms like vlan and access-port is essential for answering scenario-based questions correctly.