Muni fiber: L1 or L2?

Fri Feb 8 14:18:02 UTC 2013

On Fri, Feb 8, 2013 at 2:36 AM, Masataka Ohta <
mohta at necom830.hpcl.titech.ac.jp> wrote:

> Jay Ashworth wrote:
>
> >> As PON require considerably longer drop cable from a splitters
> >> to 4 or 8 subscribers, it can not be cheaper than Ethernet,
> >> unless subscriber density is very high.
> >
> > Oh, ghod; we're not gonna go here, again, are we?
>
> That PON is more expensive than SS is the reality of an example
> contained in a document provided by regulatory body (soumu sho)
> of Japanese government.
>
>
> http://www.soumu.go.jp/main_sosiki/joho_tsusin/policyreports/chousa/bb_seibi/pdf/041209_2_14.pdf
> .
>
>
Sorry, but I can't read Japanese, and the pictures aren't enough to explain
the thrust of the document.

Also, you keep using the acronym "SS". Maybe I'm showing ignorance, but
what are you referring to? A little Googling this morning only came up with
SS-WDM PON, which is completely different than the PON vs Active debate
we've been having.

> Assume you have 4000 subscribers and total trunk cable length
> is 51.1Km, which is the PON case with example and trunk cable
> length will be identical regardless of whether you use PON
> or SS.
>
> The problem of PON is that, to efficiently share a fiber and
> a splitter, they must be shared by many subscribers, which
> means drop cables are longer than those of SS.
>
> For example, if drop cables of PON are 10m longer in average than
> that of SS, it's total length is 40km, which is *SIGNIFICANT*.
>
> Just as the last miles matter, the last yards do matter.
>
> > Yes, a PON physical build can be somewhat cheaper, because it multiplexes
> > your trunk cabling from 1pr per circuit to as many as 16-32pr per circuit
> > on the trunk, allowing you to spec smaller cables.
>
> That is a negligible part of the cost. Cable cost is not very
> sensitive to the number of fibers in a cable.
>
>                                                 Masataka Ohta
>
>
>