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.
Professor Lasky’s note floated at the top of the instructions: “VLANs don’t just happen. You build walls where there are none.”
Alex saved the configuration: write memory .
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. 3.3.12 packet tracer - vlan configuration.pka
A quick check. PC3 was also in Accounting. It should work.
“Check,” Alex whispered, moving to S2 and S3. Repeat. Repeat. VLAN 10, 20, 30. Accounting. Engineering. Staff.
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. Professor Lasky’s note floated at the top of
Alex smiled at the virtual topology—three separate networks living on the same wires, never arguing, never colliding.
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.
The scenario: VLAN Configuration . Objective: Slice this single broadcast domain into three separate pieces of virtual reality. But it does break connectivity for any access
enable configure terminal vlan 10 name Accounting vlan 20 name Engineering vlan 30 name Staff end It felt like naming three new pets. But switches don’t wag tails. They just add lines to a file called vlan.dat .
But Professor Lasky had hidden a trap. The instructions, step 7: “Verify that PC3 cannot ping PC5.” Alex did. It couldn’t. Good.
“Allowed VLANs,” Alex muttered. “Add 30.”
He walked off. The switches hummed.
“Wait,” Alex frowned. “That’s good. But why can’t PC1 ping PC3?”
