[Beowulf] fast interconnects

Mark Hahn hahn at physics.mcmaster.ca
Mon May 22 11:55:34 PDT 2006

> > a) There's likely to be 10Gbps ethernet over ordinary cat 5e/6 cabling
> soon. (Solarflare is one company working on it)
> It is not a surprise, as you can run InfiniBand on cat 6 cables today.
> There are several solution in the market that make it happened.  

interesting, but of limited import, IMO.  cat6 will presumably be cheap
(and light and long) relative to current cx4 cables, but the real
question is when (whether?) the ethernet ecosystem will embrace
10gbase-t and make it relatively cheap.

in other words, IB-over-cat6 is nice, but it doesn't fundamentally
change the IB picture.  I still have questions about IB:

	- isn't Mellanox still the sole source for IB chips, for both
	nics and switches?  this seems odd if it's a thriving ecosystem.
	no offense intended!  yes, I know quadrics/SGI/SCI/Myri are all
	also sole-source.  but compared to the eth world...

	- price of nics has gone down significantly, close to the point
	of no resistance.  but afaikt, IB switching is still a big cost;
	are there prospects of IB switch fabrics getting anywhere close
	to gigabit costs?

	- IB people seem to be claiming quite nice latency figures 
	these days, but I don't really understand what changed to cause
	a ~7x reduction in latency.

	- IB seems to be squeezed between cheap 1G (which is dirt cheap
	and The Right Choice for most clusters), and the onset of 10G 
	(which could satisfy the subset of bandwidth-intense clusters.)  
	would there be a reason to choose IB if the eth world suddenly 
	started	shipping 10gbase-t in volume with switches costing, say,

regards, mark hahn.

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