Configuration.pka — 3.3.12 Packet Tracer - Vlan

Alex smiled at the virtual topology—three separate networks living on the same wires, never arguing, never colliding.

A quick check. PC3 was also in Accounting. It should work.

The scenario: VLAN Configuration . Objective: Slice this single broadcast domain into three separate pieces of virtual reality.

The default port between S1 and S2 (Gig0/1) was just a regular port. It saw a ping from PC1 (VLAN 10, S1) and dropped it before it reached S2.

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

switchport trunk allowed vlan add 30 Ping. Success. All three switches now carried all three VLANs. One last test. PC4 (Accounting, S2) → PC6 (Accounting, S3). Works. PC2 (Engineering, S1) → PC5 (Engineering, S2). Works.

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

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.

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

On S1, G0/1:

He walked off. The switches hummed.

“Allowed VLANs,” Alex muttered. “Add 30.”

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.

Alex did this for all three switches, matching the color-coded diagram in Packet Tracer. Red for Accounting. Blue for Engineering. Green for Staff.

But when Alex tried to ping from PC1 (Accounting) to PC5 (Engineering)…