3.3.12 Packet Tracer - Vlan Configuration.pka Online

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.

“This is too friendly,” Alex muttered. “I don’t want Accounting to talk to Engineering. They have nothing in common except coffee.”

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

Professor Lasky walked by, glanced at the screen, and said only: “Three VLANs today. Three hundred in the real world. The logic doesn’t change.”

Alex learned the hard lesson: deleting a VLAN from one switch doesn’t delete it from others. But it does break connectivity for any access port still assigned to that missing VLAN on that switch. They have nothing in common except coffee

“Wait,” Alex frowned. “That’s good. But why can’t PC1 ping PC3?”

Alex blinked. “Why would anyone—fine.” Professor Lasky walked by, glanced at the screen,

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.

But Professor Lasky had hidden a trap. The instructions, step 7: “Verify that PC3 cannot ping PC5.” Alex did. It couldn’t. Good.

“Right,” Alex groaned. “The switch doesn’t know which PC belongs to which VLAN. It’s like a hotel front desk that doesn’t ask for your room key.” Back on S1: