[160195] in North American Network Operators' Group
Re: Muni fiber: L1 or L2?
daemon@ATHENA.MIT.EDU (Owen DeLong)
Sat Feb 2 01:23:56 2013
From: Owen DeLong <owen@delong.com>
In-Reply-To: <510CA27F.7050202@vaxination.ca>
Date: Fri, 1 Feb 2013 22:22:43 -0800
To: Jean-Francois Mezei <jfmezei_nanog@vaxination.ca>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Feb 1, 2013, at 21:22 , Jean-Francois Mezei =
<jfmezei_nanog@vaxination.ca> wrote:
> On 13-02-01 22:52, Owen DeLong wrote:
>=20
>> Since the discussion here is about muni fiber capabilities and ideal =
greenfield
>> plant designs, existing fiber is irrelevant to the discussion at =
hand.
>=20
> Not so irrelevant. If the municipality wishes to attract as many
> competitive ISPs as possible, it wants to build a "standard" last mile
> that ISPs can easily interface to. One which is compatible with other
> FTTH systems.
Yes and no. As I said, I think it's more important to build a system =
that can
accommodate as many different potential technologies as possible rather
than to follow the conventional wisdom of the day developed by =
single-provider
monopoly environments.
> Currently, the standard is GPON (even though there are many variations
> to the theme).
Meh... Not in South Korea... The standard there is Gig-E to the home.
> Sone may say that having L1 service with each ISP having their OLT =
with
> splitters at the CO is an advantage. It also means that each ISP has =
to
> have its own ONTs in homes and they can all choose different configs =
for
> OLTs and the light in the fibre. Greater flexibility to differentiate
> between ISPs. (one may choose RFoG for TV with DOCSIS for data while =
the
> other is an all data link with IPTV.)
Exactly.
> But for an end user, switching ISPs would mean switching the CPE
> equipment too since the ONT installed by ISP-1 may not be compatible
> with OLT used by ISP-2.
So? I don't see that as a problem.
> Requiring an ISP to have its own OLT at the CO with its own splitter
> also raises startup costs and reduces the chances of having =
competitive
> ISP environment.
Hence my suggestion that in environments where it may make sense to do
so, the muni could offer an optional enhanced L2 service. In this case, =
the
muni would supply OLTs, ONTs, and hand off the L3 work to the =
provider(s).
> Providing L2 service means that ISPs connect to a municipal OLT, so =
they
> do not have to purchase OLTs and bother with splitters. At that point,
> it si simpler and cheaper to deploy splitters in neighbouhoods. It =
also
> reduces number of splices.
Which I advocate as an OPTIONAL additional service.
> When you do 1:1, you may have a big cable with lots of strands leaving
> the CO, but you'll have a JWI in neighbouhood where you cross connect
> the strands from CO to the strand that uses the pre-fab cable to the
> backyards of homes served.
I'm not sure what your abbreviation "JWI" means.
> So in all the calculations made on dB loss, the number of splices was
> not factored in. You're not going to get a continuous cable from the =
CO
> to the telephone pole behind a home. If you put the splitter at the =
CO
> you get the losses from the splitter, and then losses from a splice at
> the neighbouhood where trunk from CO connects to cables that runs
> through backyards.
Sure, but you get those same losses regardless of which side of the =
splitter
they are on.
>=20
> When you put the splitter in the neighbouhood, it performs both the
> splitting and the connection of the cable from CO to the backyards. So
> you eliminate one splice.
According to http://www.thefoa.org/tech/lossbudg.htm
this is about 0.3db, so reduce the served radius by ~1km.
I think I already allowed for that in proposing an 8km serving radius
for 10km optics.
Given that 48 Gig -> 2 10G switches are getting cheaper and cheaper
(even in the managed variety) to the point where being able to deploy
them would be about 1/10th the cost per port of an OLT, I'm not sure =
that
GPON is necessarily the clear winner in a carrier neutral scenario.
Put splitters in the neighborhood and don't build for home-runs, then
you eliminate the ability to introduce new technologies. IMHO, that's
a really bad bet at this point.
Owen
