----- Original Message ----- > From: "Robert E. Seastrom" <r...@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 j...@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