[Cerowrt-devel] Fiber to the yurt approved

Chuck Anderson cra at WPI.EDU
Thu Sep 25 10:53:42 EDT 2014

On Thu, Sep 25, 2014 at 07:06:30AM -0700, Dave Taht wrote:
> searching alibaba for new gear is truly an eye-opening experience...
> examples:
> http://www.alibaba.com/product-detail/Atheros-based-router-with-sfp-port_1979360314.html
> http://www.alibaba.com/product-detail/Factory-OEM-Ralink-3052-300M-OpenWrt_1923358888.html
> I am under the impression however, that SFP+ is needed for gig
> uplinks. Not that 100Mbit
> is bad...

No.  SFP was originally 1 gigabit (1000 mbit) over fiber only.  Now it
can be 100/1000 megabit dual-mode copper or fiber or 10/100/1000
megabit tri-mode copper or fiber.  SFP+ is 10 gigabit.  There are
other speeds as well, but those are used for things like Fibre
Channel, SONET, ATM, etc. rather than Ethernet.

> On Wed, Sep 24, 2014 at 11:12 PM, Joel Wirāmu Pauling <joel at aenertia.net> wrote:
> > Put as many pairs as you can fit into the conduit to leave quite a lot of
> > slack (2-5metres)
> The specific question was what form of conduit (earth burial) would be sane?
> This would be a ground burial thing where I would be comfortable with
> ground buriable ethernet, no conduit (it's a forest), but fiber looks more
> fragile.
> > We bury our splitters with ofdm break outs in waterproof boxes every 500m -
> > 2km or so for the GPON roll out and blow the Fibre to the premise from the
> > split.
> Residences and yurts are spaced about every 3 meters in distinct subsections.
> > Burying splinter boxes prevents vandalism/flooding issues and
> > accidents.
> This is a campground in california. Amusingly, a few hours after we started
> eagerly discussing digging up the ground, it started pouring rain. I'm going
> to put "discuss fiber deployment" into my bag of drought-ending tricks...
> >Con's you have to dig it up every time you want to connect
> > another pair into the ofdm. Fibre blower kit is expensive.
> I saw that a fiber blower box was 6k. There seem to be daily rentals
> available...
> > Choose your connectors on the ofdm carefully. LC style connectors are the
> > norm on SFP(+) optics and isn't angled. This is my personal favorite but
> > some dislike it. Is rarely the norm for In premise kit especially for pon.
> >
> > Angled and unangled SC connectors are norm for PON and CPE Home kit. Angled
> > is better for loss and used primarily on the splitter OFDM but easy to munge
> > if you connect angled to unangled.

Angled (APC - Angled Polish Connector) usually has a green colored
connector, while non-angled (PC or UPC - Ultra Polished Connector)
usually has a blue connector for singlemode.  You can't mate two
unlike kinds (well you can try, but the loss will be high).

Angled improves the Return Loss figure (larger negative dB value,
usually -65 dB vs. -45 dB on regular UPC) due to it preventing
reflections at the connector mating point from entering back into the
trasmit fiber causing attenuation.  Instead it causes the reflections
to divert to the side.  IME, it is used for PON and HFC networks, or
any network that sends a RF modulated signal down the fiber.  For
straight data-only deployments, usually un-angled is used.  Definitely
all SFP or SFP+ modules you find will require the regular PC or UPC
kind, not angled.

> > You might even consider just not using a splinter or OFDM patch at all and
> > just having slack and unterminated fibers. Cheap Chinese Fujikura equivalent
> > spilcers can be had for around 3000$ now. And splicing is always better than
> > patching IME.
> >
> > Have fun!
> You just hit me with more condensed jargon than I've had to deal with in many
> a month, but I think I grokked most of it. It has been really
> interesting to absorb
> an entirely new technology with your help, that of the list, and google.
> First up is just to trial something between two desparately needed points...

Outside Plant (OSP) cable is designed for outdoor use (but not
necessarily direct-burial, may still need conduit).  There are
regulations on how far into a building you can bring OSP cable (50 ft
or 50 meters?) due to fire codes.  There is also Indoor/Outdoor cable
to get around that limitation.

Given you are using regular routers or switches, you don't want PON
(star arrangement of fiber that passively splits to multiple
destinations in the downstream direction, and uses timeslots for the
upstream direction, requires special OLT and ONC gear at each end and
isn't really regular Ethernet).  So you will generally need two
strands for each point-to-point link (although there are special
bi-directional SFPs you can get that will run TX and RX over a single
strand using WDM, not recommended due to higher cost).

Do you have a central aggregation point planned?  If so, I would
home-run all the strands from each peripheral building to that point
(or rather, splice separate cables together where necessary so that
logically each building has a home run of at LEAST 2 strands, although
I would plan on at least 6 or 12 for
expansion/redundancy/spares/experimentation).  The labor is the
expensive part, so pulling as many strands as possible in one go is
the best way.  You don't have to or splice all of them or terminate
all of them onto LC/UPC connectors yet.

I can ask what our contractors recommend as far as type of conduit.

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