I've made the point in a few recent posts that InfiniBand is sticking around, and hopes that it will fade away like Token Ring, FDDI, or ATM are very much misplaced. Now in addition to the financial traders and supercomputing centers who've shown strong support for the technology, Google has released a white paper on how to
build an energy efficient data center using the interconnection technology.
Now this Google announcement came on a Mellanox (MLNX) press release, and claims an 85% power reduction, which is the sort of thing they say in the fantasy world we would all be living in if life actually existed as described in BusinessWire. Still, I'm not surprised InfiniBand switches are far more power efficient than big, Carrier Ethernet boxes.
I haven't seen the paper, but I'm going to guess the reason Mellanox can beat its chest about power savings is the Butterfly topology Google references, which does wonders for cutting memory requirements. Memory chips in switches and routers are complete power hogs. One of the benefits of the Butterfly is that it's basically a one way street, which limits forwarding decisions, and in turn how many paths and destinations need to be stored in memory chips. If someone's actually read the white paper, they can tell me if this is actually the case.
The paper describes the use of the "flattened butterfly" topology -- which is *not* the same as a butterfly network. Your description of "... the Butterfly is basically a one way street, which limits forwarding decisions..." is completely *inaccurate* and confusing. A traditional "butterfly" network has limited path diversity, however, this is not the case with a "flattened butterfly" topology which has abundant path diversity.
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