US Patent 7539150 Node discovery and communications in a network

A plurality of broadcast messages are sent from at least one node of a plurality of nodes of a network. A node is discovered based on a received message. An entry is stored, wherein the entry corresponds to the node and a timestamp that indicates a time at which the node was last discovered. A notification is made that the node is offline, in response to determining that a predetermined time has elapsed since the timestamp was last updated.