An access port normally carries a single VLAN of untagged traffic. There is one important exception: a port connected to a Cisco IP phone (or any device that speaks the same protocol) can carry TWO VLANs simultaneously - one for phone voice traffic (tagged), one for PC data traffic (untagged) that comes out the daisy-chained port on the phone. This is the voice VLAN feature. This lab configures it and verifies the result.
What you will learn
- The data VLAN + voice VLAN concept and how a single access port carries both
- How CDP signals voice VLAN configuration to a connected IP phone
- The exact CLI commands to configure data + voice VLAN on a port
- How to verify with
show interfaces switchport - The QoS implications (DSCP marking) that come along with voice VLAN configuration
What this lab does NOT cover
- Trunked voice (where the phone is a trunked uplink)
- QoS classification + queueing beyond a mention
- SIP / SCCP signaling
Topology
Download the STP+VLAN Reference Lab .yaml
Drop this into CML's Import dialog. Three IOSvL2 switches in a triangle with VLANs 10/20/99, dot1q trunks, rapid-PVST root election, and an LACP EtherChannel between SW1 and SW2.
