A network administrator is troubleshooting a scenario where IP phones connected to an access switch are unable to obtain IP addresses or reach the gateway on VLAN 50. Meanwhile, workstations on VLAN 10 connected to the same switch are functioning normally across the 802.1Q trunk link to the core switch. Reviewing the access switch configuration reveals that VLAN 50 traffic is being dropped at the trunk port, and VLAN 50 does not appear in the switch's local VLAN database. Which TWO actions must the administrator perform on the access switch to restore network connectivity for the IP phones? (Select TWO)
- Create VLAN 50 in the switch global configuration mode.Answer
- BChange the native VLAN on the trunk interface to VLAN 50 so IP phone traffic bypasses 802.1Q tagging.
- Add VLAN 50 to the allowed VLAN list on the 802.1Q trunk interface.Answer
- DDecrease the Spanning Tree Protocol (STP) bridge priority value on the access switch for VLAN 50.
Answer
The administrator must create VLAN 50 in the global configuration mode and explicitly add VLAN 50 to the allowed VLAN list on the trunk interface.
To forward Layer 2 traffic for a specific subnet/VLAN across a switched network, the VLAN must exist in the switch's local VLAN database and must be permitted on the 802.1Q trunk port connecting to the rest of the network. Creating VLAN 50 globally and adding VLAN 50 to the trunk's allowed VLAN list directly resolves both root causes.
Step-by-Step Solution
Key Concept
VLAN Trunking and VLAN Database Configuration