200-301 · Question #521
A Cisco engineer must configure a single switch interface to meet these requirements: - accept untagged frames and place them in VLAN 20 - accept tagged frames in VLAN 30 when CDP detects a Cisco IP p
The correct answer is C. switchport mode access. To support both untagged data frames in VLAN 20 and tagged voice frames in VLAN 30 on a single switch interface, the port must be configured in access mode with a voice VLAN.
Question
A Cisco engineer must configure a single switch interface to meet these requirements:
- accept untagged frames and place them in VLAN 20
- accept tagged frames in VLAN 30 when CDP detects a Cisco IP phone
Which command set must the engineer apply?
Options
- Aswitchport mode dynamic desirable
- Bswitchport mode dynamic auto
- Cswitchport mode access
- Dswitchport mode trunk
How the community answered
(29 responses)- A3% (1)
- B7% (2)
- C79% (23)
- D10% (3)
Why each option
To support both untagged data frames in VLAN 20 and tagged voice frames in VLAN 30 on a single switch interface, the port must be configured in access mode with a voice VLAN.
`switchport mode dynamic desirable` actively attempts to form a trunk link, which is not the intended configuration for a port connected to an end device and an IP phone using voice VLAN.
Configuring a switch port in `switchport mode access` allows it to carry untagged data traffic for its assigned access VLAN (VLAN 20). When combined with the `switchport voice vlan 30` command, this mode also enables the port to accept tagged voice frames from a Cisco IP phone in VLAN 30, thereby meeting both specified requirements.
Concept tested: Switch port modes and voice VLAN
Source: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/release/12_2_25_se/configuration/guide/scg/swvoip.html
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