[Beowulf] torus versus (fat) tree topologies

[Jim Lux]

----- Original Message -----
From: "Greg Lindahl" <lindahl at pathscale.com>
To: <beowulf at beowulf.org>
Sent: Friday, November 12, 2004 4:55 PM
Subject: Re: [Beowulf] torus versus (fat) tree topologies


> 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.
>
Used, for instance, in series wired Christmas  tree light strings..

One never knows though... it could have been patented by IBM.
<grin>