Muni network ownership and the Fourth

Tue Feb 5 16:39:03 UTC 2013

----- Original Message -----
> From: "Robert E. Seastrom" <rs at seastrom.com>

> > Hmm. the optics don't have auto power control?
> 
> Auto power control would apply to launch levels for the light;
> assuming a launch level of -3 dBm and lasers that were only 1 percent
> efficient (combination of spec max launch power for LX optics and
> unrealistically crummy efficiency lasers) your total power budget for
> the laser is only 50 milliwatts out of that 4 watts - wrong place to
> look for power savings. The rest is taken up by stuff like the
> ethernet chip and supporting logic in the switch, inefficiencies in
> the power supply, etc. etc.

Ah.  Didn't realize that was the split.  

> >> Anyway, in summary, for PON deployments the part that matters *is* a
> >> greenfield deployment and if the fiber plant is planned and scaled
> >> accordingly the cost differential is noise.
> >
> > I assume you mean "the cost diff between GPON plant and home-run
> > plant"; that's the answer I was hoping for.
> 
> Close; I meant "the cost difference between a home run fiber
> architecture with centralized splitters for *PON and distributed
> splitters in the field is minimal, and one gains it back in
> future-proofing and avoiding forklift upgrades down the road".

I believe that's the same assertion, yes.  :-)

> The question of where one puts the splitters (if any) is coupled to
> the PON vs. active ethernet question only insofar as AE doesn't need
> splitters - but assuming:
> 
> * $10k/month cost differential for power in the scenario above
> * unity cost for head end equipment (almost certainly wrong)
> * a 16 way split ratio (worst case; you might get 24 or 32)
> * $100 apiece splitters (24 or 32 would be marginally more)
> * today's stupid-low cost of capital
> 
> break-even point on the decision to go with a PON type of technology
> is still less than two years.

Well, some of it is how many access chassis you need to sink the ports;
Calix, for example, can do 480 ports per 10U at AE, but ...

well, they say >10k ports, but since each card is 8-GPON (x 16 subs), that's 128 * 20, which is 2560, so I have to assume they're quoting 64x GPON,
which people are telling me isn't actually practical.

Just the capital cost, though, of 20 chassis vs 1 or 2 is really notable,
at the prices those things go for.

> If you have a customer who needs the whole pipe to himself (or next
> generation optics for 10g or 100g to the couch), with centralized
> splitters the solution is easy. You re-patch him with an attenuator
> instead of a splitter (or hook him to the new kit), re-range, and go
> to town. Of course you lose the power advantages of a PON
> architecture but those customers are the exception not the rule.

Sure.  Unless, as we've been discussing, an ISP comes to town who has
all their kit pre-designed and trained, and wants to do one or the other.
(My underlying assumptions are in the "rollup" posts I put out on
Friday, if you missed it.)

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