1. A method of providing trustworthiness of communication among a plurality of communication nodes, said method comprising: arranging each of said communication nodes to perform a trustworthiness judging operation on received data elements for judging a received data element to be trustworthy or not, grouping said plurality of communication nodes into a plurality of distinguishable clusters, each cluster comprising at least two of said communication nodes, implementing in each respective cluster an intra-cluster trust mechanism such that trustworthiness of data elements sent by any member node of said respective cluster is judgable within said respective cluster, arranging said clusters such that each of said clusters comprises one or more multi-cluster-member nodes that belong to at least two different of said clusters, and routing inter-cluster traffic through said multi-cluster-member nodes.