STP 5: PortFast on Access Ports (VLAN 50 Triangle)

Bundle lab · $29.99

Configure PortFast correctly on access ports in a triangle switch loop while maintaining normal STP protection on inter-switch trunks. Force SW1 as the root for VLAN 50 and verify that only edge ports are fast-tracked. Observe the difference in host convergence with and without PortFast.

Learning objectives

• Cabling and VLAN 50 across a triangle of L2 switches (SW1–SW2–SW3) with a real loop present
• Deterministically force the STP root bridge for VLAN 50 using bridge priority (SW1 at 4096)
• Apply PortFast on host-facing access ports only and confirm it is not present on trunks
• Verify STP operation and PortFast status with show spanning-tree commands
• Validate that end hosts in VLAN 50 can communicate immediately after link-up without STP timer delays

Troubleshooting focus

• If hosts cannot communicate, confirm VLAN 50 exists on all switches and is allowed on all trunks
• If a trunk port shows PortFast, remove it immediately; PortFast belongs only on host-facing access ports
• If SW1 is not the root for VLAN 50, verify the configured bridge priority is lower than the others
• If ports flap between states, check for native VLAN mismatches or incorrect access assignments