[Beowulf] Cluster Diagram of 500 PC

[Mark Hahn]

>> my question is: do switches these days have smart protocols for mapping and 
>> routing in such a configuration?  I know that the original spanning 
>
> That's 802.3ad. Quick pointer:
> http://en.wikipedia.org/wiki/Link_aggregation

I don't think that's what I meant.  imagine instead that you have 
48pt GE switches, each of which has 4x 10G extra ports.  now, take
5 such switches and fully connect them (each switch has a 10G link
to each of the other 4 switches).  I don't think 802.3ad helps here,
since what you want is to _avoid_ a single spanning tree, which 
would necessarily have one root.

802.3ad is exactly the right thing if you simply want to stack
two such switches and want 4x10Gb inter-switch bandwidth.

I noticed that d-link appears to use 10G links for stacking, but 
has a route-discovery protocol that lets them structure the switches
into a ring.  I'm not sure they use this to reduce hop-count, though - 
perhaps just for reliability.