60 ms cross-continent

Bryan Fields Bryan at bryanfields.net
Sat Jun 20 20:11:33 UTC 2020

On 6/20/20 1:56 PM, Saku Ytti wrote:
> On Sat, 20 Jun 2020 at 20:52, Wayne Bouchard <web at typo.org> wrote:
>> And thus far, no one has mentioned switching speed and other
>> electronic overhead such as the transceivers (that's the big one,
>> IIRC.)
> This will be something from tens of meters (low lat swich), to few
> hundred meters (typical pipeline),  to 2km delay (NPU+FAB+NPU) per
> active IP device. If that is a big one, I guess it depends, cross
> atlantic, no, inside rack, maybe.

I think he might be referring to the newer modulation types (QAM) on long haul
transport.  There's quite a bit of time in uS that the encoding takes into QAM
and adding FEC.  You typically won't see this at the plug-able level between
switches and stuff.

60ms is nothing really, and I'm happy I don't need to play in the HFT space
anymore.  I do wish my home connection wasn't 60 ms across town as spectrum
wants takes TPA-ATL-DCA-DEN-NY to get to my rack. :-)
Bryan Fields

727-409-1194 - Voice

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