In an effort to reduce the amount of broadcast and multicast traffic in a broadcast domain, the router can be configured to respond to all ARP and Neighbor Discovery requests. The router will respond with the hardware address of the host that owns the IP address, if the ARP/ND entry for the Target Address exists in the router‘s ARP/ND cache. If the Target Address does not exist in the ARP/ND cache or if the entry in unresolved, the ARP/ND request will be dropped.
Use the command arp-nd-proxy-all in interface configuration mode to enable ARP/ND proxy all.