14.9.11 Packet Tracer - Layer 2 Vlan Security Apr 2026

interface range fa0/1-24 switchport mode access switchport nonegotiate On the actual trunk between switches:

interface g0/1 switchport trunk native vlan 999 Then, ensure VLAN 999 exists but is used nowhere else. No user devices, no DHCP, no routing.

Cisco’s Packet Tracer activity is an excellent, hands-on lab that forces you to think like both a network admin and a hacker. It focuses on three critical Layer 2 vulnerabilities and their mitigations: MAC Flooding , VLAN Hopping (Switch Spoofing) , and DHCP Starvation . 14.9.11 packet tracer - layer 2 vlan security

Instead of using VLAN 1 (the default native VLAN), change it to, for example, VLAN 999.

ip dhcp snooping ip dhcp snooping vlan 10,20 interface g0/1 ip dhcp snooping trust interface range fa0/1-24 ip dhcp snooping limit rate 10 no ip dhcp snooping trust Now, only the uplink port can send DHCP Offer/ACK messages. Any rogue server on an access port will be ignored. It focuses on three critical Layer 2 vulnerabilities

On any port that should not be a trunk (i.e., all end-user ports), explicitly turn off trunking:

Happy (secure) switching.

DHCP Snooping.