[Beowulf] torus versus (fat) tree topologies

[Greg Lindahl]

On Fri, Nov 12, 2004 at 06:02:08PM -0500, Patrick Geoffray wrote:

> How do you close your Torus without long cables ? Unless you stack your 
> nodes in a circle, you will need long cables.

BlueGene's trick is to attach every other node to the end, and then
come back with the unused ones. So:

Nodes: 0 1 2 3 4

Connections: 0 -> 2 -> 4 -> 3 -> 1 -> 0

No long cable. This is probably a classic solution not invented by IBM.

-- greg