Muni broadband sucks (was: New minimum speed for US broadband connections)

Baldur Norddahl baldur.norddahl at gmail.com
Thu Jun 3 16:14:30 UTC 2021


On Thu, Jun 3, 2021 at 5:41 PM Masataka Ohta <
mohta at necom830.hpcl.titech.ac.jp> wrote:

> As cabling cost is mostly independent of the number of cores in a
> cable, as long as enough number of cores for single star are provided,
> which means core cost is mostly cabling cost divided by number of
> subscribers, single star does not cost so much.
>

Sorry but that claim is completely wrong. Cabling cost scales linearly with
the number of cores. A 192 core cable is approximately twice the price of a
96 core cable. Only at very low core count does this break up somewhat. A
12 core cable is still significantly cheaper than 24 cores. A 1 core cable
is the same price as 4 cores however.

On top of that, the price to splice is also linearly related to the number
of cores to splice. Yes there is the setup time, but then working on 192
cable takes a whole day, requires larger enclosures, requires larger
manholes, while we might only need 2 (!) splices to do the same work with
GPON.

Then there is the price to the ducting. A 192 core cable requires bigger
ducts and plastic is not only expensive, it has recently become scarce.
Putting in a 24 core cable in a 10/6 duct is much cheaper than a 192 core
cable.


> Then, PON, needing large closures for splitters and lengthy drop
> cables from the closures, costs a lot cancelling small cost of
> using dedicated cores of single star.
>


Now a splitter can be mounted in a splice enclosure taking up the same
space as 12 splices. We use dome shaped water tight enclosures for 96
splices and then we replace one of the splicing trays with the splitters.
All of this fits in a handhole about 70 cm long, 60 cm wide and 30 cm deep.

Another operator here instead has the splitters in cabinets with a cabinet
for every 50 to 200 passed homes. You could build a P2P network like that,
but then you would need power and active equipment in these cabinets.

Not sure what you are talking about with regards to drop cables. The house
connection is identical in a GPON and P2P network.



> On the other hand, if PON is assumed and the number of cores in a
> cable is small, core cost for single star will be large and only
> one PON operator with the largest share (shortest drop cable from
> closures to, e.g. 8 customers) can survive, resulting in monopoly.
>


Typically the infrastructure owner runs the PON equipment and resell vlan
based access to ISPs.

Regards,

Baldur
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