Fiber terminations -- UPC vs APC

Tue Nov 20 08:35:15 UTC 2012

+1 here on going all APC on the panels, note we run a gpon network so
making that choice was fairly easy for us.  You do end up having to use a
lot of sc or lc/upc - sc/apc patch cables on the colo equipment side of
things but everything out in the field is 100% sc/apc.

Carlos Alcantar
Race Communications / Race Team Member
1325 Howard Ave. #604, Burlingame, CA. 94010
Phone: +1 415 376 3314 / carlos at race.com / http://www.race.com

-----Original Message-----
From: Lamar Owen <lowen at pari.edu>
Date: Monday, November 19, 2012 2:30 PM
To: Jeff Kell <jeff-kell at utc.edu>
Cc: "nanog at nanog.org" <nanog at nanog.org>
Subject: Re: Fiber terminations -- UPC vs APC

On Nov 19, 2012, at 4:37 PM, Jeff Kell wrote:

> Looking for some guidance/references on the use of UPC versus APC
> terminations on fiber
> cabling.  Traditionally we have done all of our fiber plant
> targeting data usage with
> UPC connectors.  We are also looking at proposals for fiber
> distribution plant for
> video, and the possibility of using some of the existing fiber plant
> for that purpose;
> as well as any new fiber plant that gets installed for video
> potentially as data.
>
> The video folks are set, determined, and insistent that they need
> APC terminations.

APC is pretty much the standard for high-power video distribution, and
for very good reasons.  The return loss is much better for APC than
for UPC, for instance, and that can be very significant depending upon
the equipment being used to drive.  Much video distribution gear,
including passive splitters and EDFA's, are only available with APC
connectors.

Mating an APC to a UPC will result in an 'air-gap attenuator' being
created, and that may be a problem.  A significant problem for some
gear, in fact.

Really high-power long-haul gear may need APC as well, even for
networking stuff.

Your choice boils down to parallel plants or only APC with UPC jumpers
for non-APC equipment.  You really really don't want to have any UPC
connectors in a really high-power path that needs APC all the way; I
have actually seen some warranty statements, for some older equipment,
primarily EDFA modules, that indicate that the warranty would be
voided if any non-APC connectors were in the path anywhere.  The
reflections from a UPC end can detune some of these lasers, and can,
in theory at least, cause permanent transmitter damage that won't be
under warranty.

You could, though, provision half APC and half UPC, since the color
coding is pretty clear.  You can even use, say, all LC on your UPC
patches and all SC on you APC patches or similar, and get both with
little danger of intermating.  I think I'd personally rather just
provision all APC in the backbone fiber runs and install APC to UPC
distribution runs to your network gear.

But you'll have to train people to always plug green connectors into
green connectors, and blue into blue, and never should green and blue
mix.

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