nanog mailing list archives

Re: GPON Optical Levels


From: Florian Lohoff <f () zz de>
Date: Tue, 13 Oct 2015 15:06:53 +0200

On Mon, Oct 12, 2015 at 10:46:59PM +0200, Baldur Norddahl wrote:
Here is a small secret: If you attenuate the PON port so the signal level
at the OLT is as low as possible, your network will be more robust against
people connecting P2P fiber media converters to your network. This is
because these devices typically have TX power that is significantly less
than your ONUs. By attenuate the signal you can bring the rogue signal
below the detection threshold of the OLT.

In my experience one way to do this is to always use 1:128 splits. Even if
you are only going to connect less than 32 ONUs, you will find that 1:128
can be more robust. In fact I discovered this little trick after we started
using 1:128 splits (for flexibility, not because we actually connect that
many clients). Because the fiber plant is shared with other service

Wouldnt a 1:32 splitter + a 9dB attenuation be the same? From
the price/performance the 1:128 splitter should be much more expensive.

We have seen happening the same converting a former p2p footprint to
GPON and somebody got a left over p2p device connected. But this was
a single incident so far.

Flo
-- 
Florian Lohoff                                                 f () zz de
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