[Beowulf] Mutiple IB networks in one cluster

Bill Broadley bill at cse.ucdavis.edu
Tue Feb 4 13:06:12 PST 2014

On 02/01/2014 08:17 AM, atchley tds.net wrote:
> The cross-bar switch only guarantees non-blocking if the two ports are on
> the same line card (i.e. using the same crossbar). Once you start
> traversing multiple crossbars, you are sharing links and can experience
> congestion.

Full backplane means no shared links, even if multiple switches are involved.

Shared links are used when you oversubscribe the uplinks, like with a half or
quarter backplane configuration.

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