Configuration.pka — 3.3.12 Packet Tracer - Vlan

interface gigabitEthernet 0/1 switchport mode trunk switchport trunk allowed vlan 10,20,30 Same on S2’s G0/1 and S3’s G0/2.

interface fastEthernet 0/1 switchport mode access switchport access vlan 10 exit interface fastEthernet 0/2 switchport mode access switchport access vlan 20 F0/3 → VLAN 30. F0/4 → VLAN 10. And so on. 3.3.12 packet tracer - vlan configuration.pka

The basement lab of Meridian Community College. Racks of aging but reliable Cisco switches hum in the corner. On a monitor, the Packet Tracer interface glows green. And so on

“Check,” Alex whispered, moving to S2 and S3. Repeat. Repeat. VLAN 10, 20, 30. Accounting. Engineering. Staff. On a monitor, the Packet Tracer interface glows green

Packet Tracer’s simulation mode revealed the truth: red packets dropping at the trunk port, rejected like a bouncer checking an expired ID.

Alex blinked. “Why would anyone—fine.”

no vlan 20 Suddenly, PC2 (Engineering, S1) went dark. Not just isolated—gone. The port was still there, but the VLAN didn’t exist. The switch didn’t drop the packets; it just shrugged.