Voice & Data VLANs: Access + Trunk Allowed Lists

Bundle lab · $29.99

Configure a two-switch access layer with data and voice VLANs on access ports and an 802.1Q trunk between switches. Add a router-on-a-stick gateway for VLAN 10/20. Verify VLAN placement, trunk status, and observe a connectivity failure caused by an allow-list misconfiguration on the inter-switch trunk—then correct it to restore intra-VLAN reachability.

Learning objectives

• Create and name VLANs for data and voice segmentation
• Configure access ports with both a data VLAN and a voice VLAN
• Build and harden 802.1Q trunks (native VLAN and allowed VLANs)
• Implement router-on-a-stick as the default gateway for user/voice VLANs
• Verify VLAN membership and trunk status with show commands
• Diagnose and fix trunk allow-list issues that break VLAN transport

Troubleshooting focus

• Detect missing VLANs in a trunk’s allowed list when same-VLAN hosts can’t talk across switches
• Spot access-port VLAN/voice-VLAN mismatches using show vlan / show interfaces switchport
• Identify native VLAN mismatches on a trunk that trigger STP/l2 issues or control-plane leaks
• Recognize when DTP negotiation is disabled but trunk mode wasn’t explicitly set on both ends
• Use end-host pings to triangulate which trunk/path is failing