Re: Muni fiber: L1 or L2?

[Owen DeLong <owen () delong com>]

On Feb 3, 2013, at 12:33 PM, Scott Helms <khelms () zcorum com> wrote:

> On Sun, Feb 3, 2013 at 2:53 PM, Owen DeLong <owen () delong com> wrote:
>
> On Feb 2, 2013, at 5:06 PM, Scott Helms <khelms () zcorum com> wrote:
>
> > Owen,
> > I think the confusion I have is that you seem to want to create solutions for problems that have already been 
> > solved.   There is no cost effective method of sharing a network at layer 1 since DWDM is expensive and requires 
> > compatible gear on both sides and no one has enough fiber (nor is cheap enough in brand new builds) to simply home 
> > run every home and maintain that.  ISPs that would want to use the shared network in general (>95% in my experience) 
> > don't want to maintain the access gear and since there is no clear way to delineate responsibilities when there is 
> > an issue its hard.
> ??
>
> Who said anything about sharing the network at L1?
>
> You did. 

No, I didn't. I said build out an L1 infrastructure such that individual connections can be leased from it. Not shared 
L1 connections.
I have never advocated shared L1 connections.

> Is it more expensive to home-run every home than to put splitters in the neighborhood? Yes. Is it enough more 
> expensive that the tradeoffs cannot be overcome? I remain unconvinced.
>
>
> This completely depends on the area and the goals of the network.  In most cases for muni networks back hauling 
> everything is more expensive.

I agree it's more expensive. The question is whether it's enough more expensive to make it infeasible. You still 
haven't come anywhere near addressing that question.

>  
>
> I'm not sure why you think it would be hard to delineate the responsibilities… You've got a fiber path maintained by 
> the municipality with active equipment maintained by the ISP at each end. If the light coming out of the equipment at 
> one end doesn't come out of the fiber at the other end, you have a problem in the municipality's domain. If the light 
> makes it through in tact, you have a problem in the ISP's domain.
>
> There is equipment available that can test that fairly easily.
>
> OK, this one made my wife get scared I laughed so hard.  You clearly have never tried to do this or had to work with 
> different operators in the same physical network.  Please, go talk to someone whose worked in the field of a FTTx 
> network and describe this scenario to them.  Its clear you don't want to hear it from me via email so please go do 
> some research.


I've talked to a few people doing exactly that. Yes, you need different test sets depending on which L2 gear is 
involved, but, in virtually ever case, there is a piece of test gear that can be used to test a loop independent of the 
configuration of the L2 gear in question.

For providers getting L1 service, it wouldn't be too hard to make this testing /  providing necessary test equipment 
part of their contract.
> > The long and short of it is lots of people have tried to L1 sharing and its not economical and nothing I've seen 
> > here or elsewhere changes that.  The thing you have to remember is that muni networks have to be cost effective and 
> > that's not just the capital costs.  The operational cost in the long term is much greater than the cost of initial 
> > gear and fiber install.
> We can agree to disagree. A muni network needs to be able to recover its costs. The costs of building out and 
> maintaining home-run
> fiber are not necessarily that much greater than the costs of building out and maintaining fiber at the neighborhood. 
> One option, for
> example, would be to have neighborhood B-Boxes where the fiber can either be fed into provider-specific splitters 
> (same economy
> as existing PON deployments) or cross-connected to fiber on the F1 cable going back to the MMR (home-run).
>
>
> We can agree all we want, that doesn't change history.  Handing out connections at layer 1 is both more expensive and 
> less efficient.  Its also extremely wasteful (which is why its more expensive) since your lowest unit you can sell is 
> a fiber strand whether the end customer wants a 3 mbps connection or a gig its the same to the city.  I'm not saying 
> you shouldn't sell dark fiber, I'm saying that in 99% of the cities you can't build a business model around doing 
> just that unless your city doesn't want to break even on the build and maintenance.

If it's $700 per home passed to build out home-run fibers (which seems to be a reasonable approximation from earlier 
discussions), then there's no reason you can't sell $40/month service over that where the L1 component is a $10/month 
($7 for capital recovery, $3 for operations and support) pricing component.

By my estimates, to become truly impractical, you'd have to get somewhere north of $1500 per home passed.


>  
> The only additional cost in this system over traditional PON is the larger number of fibers required in the F1 cable.
>
>
> PON networks aren't deployed this way and if you're going to backhaul all of the connections to a central point you 
> wouldn't run PON.   PON is worse in every performance related way to PON and the only reasons operators deploy it 
> today is because its less expensive.  Its less expensive because you don't have to backhaul all of the connections or 
> have active components at the neighborhood level.

Then don't deploy PON. I don't care whether PON gets deployed or not. You keep coming back at this as if PON is somehow 
the goal. Personally, I'd rather see Gig-E in every home and be done with it. 

However, the point is that building the infrastructure in that manner doesn't cost much more than building out 
traditional PON infrastructure (if you're doing it from greenfield) and it can support either technology.

Owen