[Beowulf] How to configure a cluster network

[Mark Hahn]

> It is my sacred duty to rescue hypercube topology. Cool Preceeds Coolant :-)

I agree HC's are cool, but I think they fit only a narrow ecosystem:
where you don't mind lots of potentially long wires, since higher dimensional
fabrics are kind of messy in our low-dimensional universe.  also, HC's
assume intelligent routing on the vertices, so you've got to make the 
routing overhead low relative to the physical hop latency.

it does seem like there is some convergence to using rings onchip,
fully connected graphs within a node and fat trees inter-node.
one unifying factor is that these are all point-to-point topologies...