This is a Broadcom Tomahawk 4 64-port 400GbE Switch Chip

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Terry Kennedy

Well-Known Member
Jun 25, 2015
New York City
I would love to see some site like Zeptobars image the innards of this chip.

I can't imagine how they bond all of the connections from the silicon to the package. I'm sure we're way past bond wires here, but just routing direct bonding to all of those pins has got to be crazy. I assume the PCB the socket is on routes pins to many different PCB layers to get the signals where they are needed.
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Well-Known Member
Feb 3, 2019
I was hoping @Patrick film the switch power up and maybe reach stable state and get a figure on idle power. Those fans look like typical blade fans. We have some blades in our lab and I'm not fond of being in the same room when they ramp up, howling away. I remember testing a 1RU 400G switch from Arista and the power usage wasn't that bad.

Looks like current 400G MM transceivers at this time are all MPO-16. So much for "future proofing" with "MPO." At least with SMF you can get transceivers that require MPO-12/duplex LC. There's also several power consumption tiers on's website: 8, 10, 14W. The former 2 use 7nm silicon and 14W from 16nm parts. Very nice of FS to include that info. The 16nm parts are also 3-4x or more the price of 7nm parts.
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Staff member
Dec 21, 2010
Between this and the servers to go around it, we had to do it in the data center. Assume this is loud.