Abstract: The invention ensures that a single and consistent reply is made to ARP request in a system of connected IP networks. When an adapter (A) becomes active, the owning host sends an ARP advertisement into the network over the adapter. If the advertisement is also received at the sending host over a different adapter B, then the host knows that adapter B is on in the same physical network as adapter A and B can be designated as a backup adapter for A and A can be designated as backup adapter for B. If adapter A fails or becomes inactive, the host resets the backup adapter field for any adapter it owns for which A is marked as the backup adapter. If a backup adapter B has been designated for A, the host also sends an ARP advertisement associating MAC-B with IP-A. This allows network connections originally served via adapter A to continue non-disruptively over adapter B and it also provides access to the host for subsequent new connections.

Abstract: The invention ensures that a single and consistent reply is made to an ARP request in a system of connected IP networks. When an adapter becomes active, the relative network on which it resides is determined by transmitting control packets over it and all other adapters known to the host and observing if and where responses are returned to the adapters. One adapter on a network is designated as active. If the same network contains other adapters, they are marked as standby adapters for the purpose of responding to ARP messages. Special processing is provided for offload adapters that perform there own ARP processing.

Abstract: The invention ensures that a single and consistent reply is made to ARP requests in a system of connected IP networks in which each host can contain combinations of host adapters, offload adapters and virtual IP addresses.