This read-write enumerated INTEGER specifies whether the port responds to ARP requests for addresses where this device is the next hop in a routed path, valid only when sprotoIpRoute is enabled. An admin enables proxy ARP here so hosts that don't understand routing can still reach remote subnets by ARPing as if the destination were local. Enabling sprotoArpProxy would let hosts on a subnet without a configured default gateway still reach other subnets by treating this router as if it were locally present.