Patent ID: 7436783

Claim:
A method for detecting a device that incorrectly responds to address-resolution-protocol (ARP) requests, comprising: sending an ARP probe for a link-local address; when a response is received to the ARP probe, sending an ARP request to the responding device asking for an Ethernet address associated with a reserved IP address, wherein the reserved IP address is an Ipv4 link-local broadcast address 169.254.255.255 or an IPv4 link-local address 169.254.0.0, which should not be assigned to any device; and if a response is received from the device to the ARP request, placing the address of the device on a black list associated with a range of link-local IP addresses: and ignoring subsequent ARP responses from source addresses in the black list for the link-local address range, so that subsequent ARP responses pertaining to that address range from the device will be ignored.