V-269961

Discussion

DAI intercepts ARP requests and verifies that each of these packets has a valid IP-to-MAC address binding before updating the local ARP cache and before forwarding the packet to the appropriate destination. Invalid ARP packets are dropped and logged. DAI determines the validity of an ARP packet based on valid IP-to-MAC address bindings stored in the DHCP snooping binding database. If the ARP packet is received on a trusted interface, the switch forwards the packet without any checks. On untrusted interfaces, the switch forwards the packet only if it is valid.

Check Content

Review the switch configuration to verify that DAI feature is enabled on all user VLANs.

Verify that each user VLAN has arp inspection enabled.

!
interface vlan200
 no shutdown
 arp inspection
!
interface vlan201
 no shutdown
 arp inspection

If ARP inspection is not enabled on all user VLANs, this is a finding.