CCNA Foundations Series: Layer 2 Day 5

Archive lab

Implement VLANs, 802.1Q trunking, router-on-a-stick inter-VLAN routing, and access-layer port security on a compact branch network with two access switches and two endpoints. You will configure segmentation (VLANs 10, 20, 99), hardened trunks with a dedicated native VLAN 999, Layer 3 gateways on a core router, and sticky MAC port security on user-facing ports. Verify end-to-end reachability and remediate common misconfigurations like missing allowed VLANs, native VLAN mismatches, and unauthorized endpoint moves.

Learning objectives

• Create VLANs and assign switch access ports to the correct VLANs
• Build hardened 802.1Q trunks that explicitly allow VLANs 10, 20, and 99 with native VLAN 999
• Implement inter-VLAN routing via router-on-a-stick subinterfaces on the core router
• Enable and verify sticky MAC port security on access ports with a single allowed device
• Detect and correct Layer 2 errors including wrong VLAN assignment, missing allowed VLANs on trunks, and native VLAN mismatches
• Validate end-to-end host reachability and default gateway behavior from the endpoints

Troubleshooting focus

• Verify every link's interface status and IP addressing (`show ip interface brief`) and correct any interface that is down or misaddressed.
• Confirm each device's running configuration matches the lab objective, and bring any interface, route, or service that is not in its expected state back to health.
• Trace end-to-end reachability with ping/traceroute and isolate the first hop where forwarding fails.