CCNA Foundations: L2 Day 7 — VLANs, Trunks & Port Security

Archive lab

Deploy VLANs, hardened 802.1Q trunks, router-on-a-stick inter-VLAN routing, and sticky port security in a compact branch topology. Verify from real hosts and troubleshoot common misconfigurations.

Learning objectives

• Create VLANs and assign user-facing access ports to the correct VLANs
• Establish 802.1Q trunks with explicit allowed VLANs and a hardened native VLAN
• Implement inter-VLAN routing using router-on-a-stick subinterfaces
• Configure and verify sticky port-security with BPDU Guard and PortFast on access ports
• Troubleshoot same-VLAN and inter-VLAN connectivity, and recover from port-security violations

Troubleshooting focus

• Same-VLAN hosts cannot ping: check access VLAN assignment and VLAN existence on both switches
• No inter-VLAN routing: verify router subinterfaces, 802.1Q encapsulation, and allowed VLANs on trunks
• Port security err-disable: clear the violation, confirm sticky MAC and maximum values, and re-enable the port
• Native VLAN mismatch: ensure the same native VLAN on both ends of every trunk and prune VLAN 1