Patent ID: 7471684

Claim:
A network implementing address resolution protocol (ARP), said network comprising: a first device that operates as a first gateway for a first sub-network that has at least one first network client device, said first device having an associated first trusted ARP cache (TARPC) that maintains correct mapping of an IP address to a respective MAC address of each of the at least one first network client device; a second device that operates as a second gateway for a second sub-network connected to the first sub-network, said second sub-network also having at least one second network client device, said first device having an associated second TARPC that also maintains correct mapping of an IP address to a respective MAC address of each of the at least one second network client device; and logic associated with ARP functionality of said first device for authenticating an ARP response received by said first device, wherein when said ARP response contains a different MAC address to IP address pairing from a pairing contained in the TAPRC of either said MAC address or said IP address, said TARPC is not updated to reflect the address mapping within the ARP response, wherein said logic for authenticating a received ARP response includes: first logic for comparing said MAC address with all MAC addresses within the first TARPC of the first device; second logic for comparing said IP address with all IP addresses within the first TARPC of the first device; third logic that forwards the addresses of the ARP response to the second device for completing a comparison within the second TARPC when said second logic for comparing at said first TARPC provides a match of one of said MAC address or said IP address; and fourth logic for updating the first TARPC with the MAC address and IP address pairing of the ARP response when said comparing at said first TARPC does not yield a match of either said MAC address or said IP address; wherein when both the MAC address and the IP address pairing of the ARP response matches a pairing of MAC address and IP address at the first device, the ARP response is authenticated.