[148969] in North American Network Operators' Group
Re: LX sfp minimum range
daemon@ATHENA.MIT.EDU (Wayne E Bouchard)
Thu Jan 26 18:20:24 2012
Date: Thu, 26 Jan 2012 16:19:38 -0700
From: Wayne E Bouchard <web@typo.org>
To: Gary Buhrmaster <gary.buhrmaster@gmail.com>
In-Reply-To: <CAMfXtQxEpivc=sJf5V7VhnijF1WebeGd+c_PvtD+NVcrdgv10w@mail.gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Thu, Jan 26, 2012 at 10:48:05PM +0000, Gary Buhrmaster wrote:
> On Thu, Jan 26, 2012 at 13:47, David Storandt <dstorandt@teljet.com> wrote:
> > You can put a 3dB or 5dB optical pad on the link if the receiver can't
> > handle zero-distance optical power.
>
> As I recall, the problem may not only be the power
> (which can cause receiver saturation), but issue that
> fibre paths shorter than (around) 2-10m do not properly
> condition the light(*), which can result in some issues
> at the receiver.
>
> Gary
>
> (*) My memory says modal distribution issues.
> While 'single mode' fibre only supports one
> mode of transmission, it takes a short distance
> for the fibre to really be single mode. You can
> use a mode filter to address the problem, or just
> use fibres that are at least a few meters.
When optics started to become scarce at various times, I've done a
number of back-to-back connections using SM fiber and have had zero
issues. I wouldn't even worry about it. Remember, many carriers won't
even touch MM and they aren't chronically reporting issues or going to
lengths to work around them.
-Wayne
---
Wayne Bouchard
web@typo.org
Network Dude
http://www.typo.org/~web/
