----- Original Message -----
From: "Robert E. Seastrom" <rs@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@baylink.com Designer The Things I Think RFC 2100 Ashworth & Associates http://baylink.pitas.com 2000 Land Rover DII St Petersburg FL USA #natog +1 727 647 1274