Take the time to run this lab. Break it on purpose. Watch the show port-security , show dhcp snooping binding , and show interfaces status err-disabled outputs.
Many network admins focus exclusively on routing, VLANs, and redundancy—but forget that Layer 2 is the most intimate part of the network. Once someone is plugged into your switch, the "perimeter" has already been breached. 14.9.11 packet tracer - layer 2 vlan security
So fire up Packet Tracer, load the 14.9.11 lab, and start typing. Each command you enter is a lock on the door, keeping attackers exactly where you want them—out. Take the time to run this lab
interface range fa0/1-24 switchport mode access switchport nonegotiate Many network admins focus exclusively on routing, VLANs,
Layer 2 security is invisible when done right. But when it's missing, the whole network crumbles.
Every port connected to a PC or printer should be an access port. The lab emphasizes two critical features: PortFast and BPDUguard .