[c-nsp] power requirement for WS-X614E-GE-45AT in reverse POE mode

[Łukasz Bromirski]

Nick,

> On 01 Apr 2015, at 14:35, Nick Hilliard <nick at foobar.org> wrote:
> 
> On 01/04/2015 08:38, Gert Doering wrote:
>> If I run a WS-X6148E-GE-45AT in reverse POE mode (feeding power into
>> the 6500), but do not use the ports for actual switching, will the line
>> card still require power?
> 
> I've run this configuration in production on a number of occasions and it
> works quite well up to and including powering up a fully loaded 6509.

I’ve digged up some old docs, and while they’re internal only,
I can share that it doesn’t work on the NEBS chasiss.

> There are two things you need to be careful about: first, you need to
> ensure that you get the POE load balancing right across all the port groups
> on this particular blade.  If you inject too much power into a single port
> group, parts of the blade will suffer from brownout.

There’s other thing to note here - watch out for DFCs installed in
the chassis. The reverse-PoE trick causes a lot of failures here.
I wouldn’t do that kind of deployment with any DFCs in the chassis.

> One of the local data centres is looking into this as a mechanism for doing
> remote power supply for some section of their data centres which have
> inadequate input power supply.  I'm interested to see how it will scale, as
> obviously there are going to be some issues with UTP cross-connects.  I
> believe they're also looking at using PoE over fibre, due to the higher
> capacity available.  Will let you know how it pans out.

PoE over fibre? Nah, you must have had misunderstood the specs.

-- 
"There's no sense in being precise when |               Łukasz Bromirski
 you don't know what you're talking     |      jid:lbromirski at jabber.org
 about."               John von Neumann |    http://lukasz.bromirski.net