1. A partially interconnected topological network, comprising: at least six topological nodes, wherein a topological node is a single physical node or a group of interconnected physical node' or part of a physical node or a group of interconnected physical nodes and parts of physical nodes, each topological node having at least three point-to-point topological links connecting it to some, but not all, of the at least six topological nodes, wherein P groups of Q topological nodes are arranged so that each topological node within a group is connected to every other topological node within that group and to exactly one topological node in every other of the P−1 groups, where P and Q are great than two, and where P is not equal to Q, and where there is at least one choice of routing between any two topological nodes, and where said at least one choice of routing further comprises either two point-to-point topological links connected in series at another of the topological nodes or a direct point-to-point topological link between the two topological nodes.