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by btoptical 4143 days ago
These big switch boxes typically end up being about thermal management and this box looks like thermal design was an afterthought. Also I'm not sure the power entry design is really all that smart. Generally speaking if you're in the market for a 640Gb/s switch (or 3.8Tb/s switch), does your data center really not have access to 48V power? The AC/DC conversion wastes power and space.

The QSFP's are "spaced for optimal airflow." However this spacing seems to neglect cooling the QSFPs themselves. Belly-to-belly mounting of modules is usually the most thermally challenging way to arrange them. The heat dissipated by the QSFP's is generally directed towards the top of the module. By placing open air channels between modules, they have effectively ensured that little to no air flows over the QSFP heat sinks (which is not shown). So there is probably a limitation on which reach codes are supported. My guess is that because of the thermal limitations of this design, it's not truly non-blocking in all reach configurations.
2 comments
wmf 4143 days ago
does your data center really not have access to 48V power?

No, they really don't. I've never heard of 48V outside of telco.

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btoptical 4142 days ago
I've been to lots of them all over the world, names you'd recognize, and they've all had 48V.
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DiabloD3 4142 days ago
Facebook's Open Rack project is based around 48v.
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jacquesm 4142 days ago
It's pretty common here (nl), you have to ask for it but it is usually available. I'd advise against it because you're deviating from the bulk but if you need it you can usually get it, especially at the larger colocation facilities.
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teh_klev 4142 days ago
Yes they do. My old employer TeleCity installed 48v as standard, for their telco customers.
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spacecowboy_lon 4142 days ago
All the Pro's (Cisco Juniper etc) offer 48v Kit as server makers targeting the carier grade market.
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seany 4142 days ago
I have 48v in both my home rack, and the offices rack.
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jacquesm 4142 days ago
This is true, however: 48V circuits are generally priced 'per-amp' just like 120V or 240V circuits. That translates into much higher cost-per-watt and with the efficiency of AC switching supplies being well over 90% you're probably better off from an economics point of view of getting the highest voltage supply that you can get and then to step down in your rack mounted devices.
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