Muni fiber: L1 or L2?

Sat Feb 9 15:22:19 UTC 2013

----- Original Message -----
> From: "Masataka Ohta" <mohta at necom830.hpcl.titech.ac.jp>

> Robert E. Seastrom wrote:
> 
> >> Let's assume 4:1 concentration with PON.
> >
> > Why on earth would we assume that when industry standard is 16 or
> > 32?
> 
> That is because additional 4:1 concentration is usually at CO,
> which does not contribute to reduce the number of fibers in a
> trunk cable.

Not to my understanding.

> > 16 is a safe number.
> 
> Do you mean a splitter in field should be shared by 16
> subscribers?

He means that, yes.

> Then, with the otherwise same assumptions of my previous mail,
> total extra drop cable length for PON will be 204km, four times
> more than the trunk cable length.
> 
> Thus, it is so obvious that SS is better than PON.

Nope.  We're all looking at you funny because your math seems *exactly*
backwards.

Let me plot it for you.

Assume 100m from the access mux (OLT) to the ONT:

2M from the OLT to the CO patch
73M from the CO patch to the neighborhood pedestal
25M from the pedestal to each house (assume a spherical neighborhood).

So, if we put the splitter in the pedestal, splitting 16 houses, we get

2 + 73 + (25 * 16) = 475 meters of total glass, plus 1 16:1 splitter.

If we put the splitter in the CO (which I believe is what you mean by
"SS"; we call it "home-run" fiber), you get:

2 + ((73 + 25) * 16) = 1570 meters of total glass, optionally plus 1 16:1
splitter, if you're still doing PON, instead of AE.

So, over three times as much fiber if you're not putting the splitter
in the field, which is... the opposite of what you assert?

Or am I dense?

Cheers,
-- jra
-- 
Jay R. Ashworth                  Baylink                       jra at baylink.com
Designer                     The Things I Think                       RFC 2100
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