[148966] in North American Network Operators' Group
Re: LX sfp minimum range
daemon@ATHENA.MIT.EDU (Gary Buhrmaster)
Thu Jan 26 17:48:20 2012
In-Reply-To: <CAExLYCoyFfsDDvxVOtoVTHarLmWGeTw4pAQ9iMRFD1L9kCdxUg@mail.gmail.com>
Date: Thu, 26 Jan 2012 22:48:05 +0000
From: Gary Buhrmaster <gary.buhrmaster@gmail.com>
To: David Storandt <dstorandt@teljet.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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.
