Editing Cisco Commands (section)

=== Notes ===
* Requires '''DHCP Snooping''' to build the ARP binding table (enable with <code>ip dhcp snooping</code> + <code>ip dhcp snooping vlan ...</code>).
* Only trusted ports can send unlimited ARP replies/packets (no validation or rate limiting).
* Access ports should remain '''untrusted''' to enforce checks.
* Commonly deployed with '''PortFast + BPDU Guard''' on access ports for loop/spanning-tree protection.
* For non-DHCP environments, use static ARP ACLs: <code>ip arp inspection filter arp-acl-name vlan 10</code>.
* Often combined with '''IP Source Guard''' (<code>ip verify source</code>) on access ports to filter IP traffic based on the same bindings.
* Rate limiting helps prevent DoS; monitor with <code>show ip arp inspection statistics</code> and consider <code>errdisable recovery cause arp-inspection</code> for automatic port recovery.
* Additional validation (<code>src-mac</code>, <code>dst-mac</code>, <code>ip</code>) catches MAC spoofing or malformed packets beyond basic binding checks—enable at least <code>src-mac</code> and <code>ip</code> in most production setups.
* DAI is ingress-only (checks incoming packets on untrusted ports).