A network technician is configuring a Layer 2 switch port connected to an IP phone, which in turn bridges a connection to a desktop workstation. The switch port is configured to handle traffic for both Data VLAN 10 and Voice VLAN 20. Which TWO of the following statements correctly describe how the switch processes Ethernet frames on this port? (Select TWO.)
- Traffic originating from the desktop workstation arrives untagged and is assigned to Data VLAN 10 by the switch port.Answer
- Voice traffic destined for the IP phone is transmitted from the switch port tagged with an 802.1Q header for VLAN 20.Answer
- CThe switch port must perform Layer 3 routing locally between VLAN 10 and VLAN 20 before forwarding frames out an upstream link.
- DIf a native VLAN mismatch exists on an upstream trunk, untagged frames received on the port are automatically dropped by ingress security filters.
- EThe switch inspects incoming untagged frames at Layer 3 to determine their destination IP subnet before assigning them to VLAN 10.
Answer
The correct statements are that traffic originating from the desktop workstation arrives untagged and is assigned to Data VLAN 10, and voice traffic destined for the IP phone is transmitted tagged with an 802.1Q header for VLAN 20.
When an IP phone and desktop PC share a single switch port, the switch handles PC traffic as untagged data belonging to the configured Data VLAN. Traffic intended for the IP phone is encapsulated with an 802.1Q tag specifying the Voice VLAN, enabling the phone to separate its voice traffic from the workstation's data traffic.
Step-by-Step Solution
Key Concept
802.1Q frame tagging behavior on switch ports configured with voice and data VLANs