Patent ID: 6678725
Filing Date: 2004-01-13
Classification: H04L

Abstract:
For use in a network of multiple computing hosts using the Internet Protocol (IP) and the Address Resolution Protocol (ARP), a method executed by a first host of processing ARP requests for an offload adapter X, where the offload adapter X itself processes ARP requests independent of the first host, comprisingin response to the recognition of activation of the offload adapter X by the first host: registering with the offload adapter X a mapping of the IP address for adapter X with a Media Access Control (MAC) address of the adapter X, whereby in response to the registration, the offload adapter X broadcasts an ARP advertisement to all hosts in the same network as offload adapter X, the advertisement mapping the IP address of adapter X to the Media Access Control (MAC) address of adapter X, and determining what physical network contains the offload adapter X, in response to the inactivation of offload adapter X: determining if there is another adapter Y owned by the first host and in the same physical network N as offload adapter X, by a) broadcasting an IP packet with a hop count of one over offload adapter X to one adapter in each physical network known to the first host, (b) activating a timer with a timeout interval sufficient to receive a return of all packets broadcast in the last step, c) if the packet broadcast in step a) returns to the first host over an adapter Z over which the broadcast packet was sent in step a), assigning the offload adapter X to the same network as adapter Z, d) if the timer of step b) times out without a return in step c) of a broadcast packet, assigning offload adapter X to a new network known to the first host, and if there is another adapter Y in network N, designating adapter Y as the active adapter for the purpose of processing ARP requests.