DC Power choices (was Re: Network visibility)

Jay R. Ashworth jra at baylink.com
Fri Oct 22 05:13:00 UTC 2021

One of the 4 or 5 datacenters in downtown Tampa had a telco or offshoot in
their spaces, when I took All The Tours about 9 years ago.  

They have 8x750MCM hauling -48VDC from their power plant to the cage in question.

On each side.

It was, in fact, pretty impressive to look at.  But I was a little worried about 
the loading on the building frame.  :-)

And while I think there might be advantages in running power supplies in gear
at -48, I'd want to rectify it in the cage, preferably from 480/3ph.

-- jra

----- Original Message -----
> From: "Lady Benjamin Cannon of Glencoe, ASCE" <lb at 6by7.net>
> To: "Mark Tinka" <mark at tinka.africa>
> Cc: "NANOG Operators' Group" <nanog at nanog.org>
> Sent: Thursday, October 21, 2021 4:50:10 PM
> Subject: Re: Network visibility

> Outside the datacenter is where DC power really shines in my opinion.  Inside
> the DC, everything is AC now and probably for the best.
> We never came up with a modular standard for -48VDC. Perhaps that could have
> changed things.
> But it sure is nice having 72hrs of battery run time in the field/edge -
> although those are becoming mini data centers themselves and are in turn also
> slowly going AC.
> Ms. Lady Benjamin PD Cannon of Glencoe, ASCE
> 6x7 Networks & 6x7 Telecom, LLC
> lb at 6by7.net
> "The only fully end-to-end encrypted global telecommunications company in the
> world.”
> FCC License KJ6FJJ
> Sent from my iPhone via RFC1149.
>> On Oct 20, 2021, at 10:19 PM, Mark Tinka <mark at tinka.africa> wrote:
>>> On 10/20/21 20:37, Lady Benjamin Cannon of Glencoe, ASCE wrote:
>>> -48VDC power is still the best.
>> I really envy folk that love DC for networking gear :-).
>> Work in 2007 was an all-DC network. I rebuilt it into AC, considering the ISP
>> also owned the data centre (most of whose customers bought AC). The space we
>> freed up and the ease of deployment was night & day.
>> Currently, we obviously need DC for the terrestrial Transport and wet plants
>> (because that's just how classic telco rolls), but I also switched all IP/MPLS
>> gear to AC soon as I arrived. Heck, even the Arbor (now Netscout) gear, as well
>> as the HP server rack, was loaded with DC power supplies. Those things just had
>> to go.
>> There is an avenue of pleasure in not having to spend inordinate amounts of time
>> adding major electrical planning to deploying/decommissioning a router, switch
>> or server.
>> But yeah, I know the AC vs. DC discussion can become a rat hole.
>> I'm aware of data centre operators now providing DC as an option for their
>> expansion projects, when they previously had it as the norm, FWIW.
> > Mark.

Jay R. Ashworth                  Baylink                       jra at baylink.com
Designer                     The Things I Think                       RFC 2100
Ashworth & Associates       http://www.bcp38.info          2000 Land Rover DII
St Petersburg FL USA      BCP38: Ask For It By Name!           +1 727 647 1274

More information about the NANOG mailing list