Patent ID: 8861527

Claim:
A method of operating a computerized device, comprising: becoming established as a cluster proxy node of a cluster in an overlay network, the overlay network being a hierarchical cluster tree (HCT) overlay network on an underlying physical network, the HCT overlay network including two or more successively higher levels of clusters of local area networks (LANs), each cluster at a given level including a respective subset of the LANs as member LANs separated from each other by no more than a respective level-specific distance in the physical network, the LANs being uniquely associated with corresponding sub-spaces of a key space defined in the overlay network; maintaining a routing table and respective channels to a parent cluster and one or more member LANs of the cluster, the routing table and channel to the parent cluster serving as sources of routing information for reaching the LANs of the overlay network, the routing information associating each LAN with a physical-network address of a corresponding LAN representative node of the LAN, the routing table including at least that portion of the routing information that associates each member LAN of the cluster with the physical-network address of a corresponding LAN representative node; and in response to receiving routing request messages from nodes of the member LANs of the cluster, each routing request message including a respective key value from the key space of the overlay network, returning corresponding routing response messages each including physical-network address information from the routing table and/or the parent cluster, the physical-network address information of each routing response message including a physical-network address of a LAN representative node of a request-specific LAN whose associated sub-space contains the key value included in the corresponding routing request message, wherein the overlay network employs a two-level distributed hash table (DHT) organization for distributed storage of data items, the two-level DHT organization including separate LAN-level and node-level hash functions defining respective key spaces, the LAN-level key space containing the key values carried by the routing request messages, and wherein, for each cluster at a given level, the level-specific distance is a maximum hop count equal to a maximum number of routers along a shortest path in the physical network between any pair of the LANs of the cluster.