Always nice if you can ring all your remotes/cabinets.  
But you can home run the customers of feed many off of a single strand.  We put 
splitters in splice cases as needed but I put in enough strands to do active 
ethernet if we want.  Very flexible.  If you cut down the the number of splits 
you can reach farther, just like a coaxial network.  However the reach is crazy 
compared to coax.  I have heard of splits as high as 128 per strand.

All of our new stuff is XGS-PON.  Dropped a bunch of money on it and have not 
even used it yet.  


From: Mark Radabaugh 
Sent: Saturday, March 16, 2024 11:04 AM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] PON question

XGS-PON can theoretically run at 100km, though 60km is about the practical 
limit we have seen,   With a active cabinet in the center and a 60km reach you 
can have an effective diameter of ~70 miles.   With slack, routing, sag, etc. 
50 miles is a possibility for cabinet spacing. 

In the rural areas we use a 10 mile radius with active cabinets 20 miles apart. 
   The active cabinet feeds unpowered splitters either in splice cases along 
the way, and also feeds passive splitter cabinets in the pockets of density 
(subdivisions, villages, towns).    If the density in a village becomes high 
enough (or grows) the passive cabinet can be changed to an active cabinet and 
the fiber previously used to feed splitters becomes your 100G feed into the 
cabinet.   

The cabinets that are 20 miles apart have a ring (well, more of a mesh) feed of 
100G links to them to provide redundancy, but there is no protection for the 
PON customers on the passive side.   There are ways to provide for PON 
redundancy including dual fed PON’s with a live / standby link, but it’s 
significantly more complex to engineer (and IMHO not worth the complexity) 
given the overall reliability and simplicity of GPON.   For a high value 
customer that needs redundancy active fiber is simpler to deal with for 
creating redundancy.

Mark



  On Mar 15, 2024, at 7:57 PM, Ken Hohhof <khoh...@kwom.com> wrote:

  Since there are FTTH people here and I’m mostly ignorant of such things, 
maybe someone can clear something up for me.
   
  I always assumed a PON based FTTH system had a topology kind of like HFC.  I 
expected fiber down the street with splitters, but fed by some sort of 
neighborhood node in a cabinet with power and electronics, fed by active EPL 
style fiber.  Which could have redundant paths, rings, etc. so a fiber cut 
wouldn’t take down a whole town or multiple towns, the backbone traffic would 
reroute.
   
  I’ve been told this is not the case.  And that instead, each PON could go 
back over a strand to a headend several towns and many miles away, all passive.
   
  Sorry for the poor description of my question, hopefully you can figure out 
what I’m asking.
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