Muni fiber: L1 or L2?

Scott Helms khelms at zcorum.com
Tue Feb 5 18:41:40 UTC 2013


> You *put active equipment out in the physical plant*.
>
> I'm sure that there are some physical plant design criteria that permit
> that decision, but mine isn't one of them, for reasons I believe I've made
> fairly clear.
>
> You disagree with some of those as well, of course, but you understand
> *that* I have made them, and I would expect, therefore, also why this
> entire subthread isn't germane to the problem I'm trying to solve, right?
>

I've tried to make clear that yes, in some scenarios (and your situation
may well fit here) that it makes sense so I think we can drop this portion.



>
> > > Owen's assertion (and mine) is that a loop architecture *requires*
> active
> > > equipment, suited to the phy layer protocol, at each node. And while
> those
> > > loop fibers are running SONET, they can't be running anything else at
> the
> > > same time.
> >
> > You're confounding the physical layer topology with the layer 2 protocol.
> > You can't run SONET and Ethernet on the same physical fiber at the same
> > time (unless you use WDM but that's confusing the discussion) but you'd
> > never build a ring of fiber with only two strands.
>
> Certainly not.
>
> But a ring a) requires *some kind* of active equipment between the MDF
> and the ONT, and b) does not support PtP at all.
>
> So, *for my stated purposes*, it's not an acceptable alternative.
>

Right, I'm questioning the value of and required number of point to point
connections.  You certainly can do dozens of point to point connections
with a hub and spoke by simply having a patch panel where your cabinets
(which you'll probably have anyhow).


>
> > > > There is nothing about a hub & spoke architecture is this harmful
> > > > or even suboptimal for doing Gig-E directly to end users today.
> > >
> > > You propose to run a ring *for each subscriber*? Or put active gear
> > > in the field to mux the subscriber AE loops into a SONET ring?
> > >
> > > Or some other approach I don't know is possible?
> >
> > SONET is simply the legacy (and expensive) way that telco's used to build
> > rings. I'd neither use it nor recommend it for much of anything today.
> > Calix, Occam(also Calix now), Adtran, and all the other guys who play
> > in this space will happily construct a Gig/10G/40G Ethernet ring in the
> > same shelf you're going to be buying to put your GPON or AE line cards
> in.
>
> I'm sure, but it's still a ring.
>
> If I ever want to upgrade it, I have to do a lot more than rack new gear
> in my "CO", and then move patch cords one at a time.
>

Not really, all that changes (and this does matter) is where you swap cards
out.

>
> > > I infer from that continuation of your thought that you mean the
> > > second: active optical muxes out in the plant.
> > >
> > > I'm sure I've made clear why that design limits me in ways I don't
> > > want to be limited when building a fiber plant for a 50 year lifetime,
> > > but let's address your responses below.
> > >
> >
> > The only limitation you have is a limited supply of total fibers
> > (hint, this is a big reason why its cheaper to build and run).
>
> Nope, that is, in fact, not the only limitation; the others have been
> expressed or implied, but are left as an exercise for the student.
>

Then I'd have continue to say none, since I've done all of the things
you're saying are limitations.  If your position was something like, "We
did the economic study and it will cost us less to home run everything than
to place remote cabinets with power." I'd have never questioned you at all.
 I know you've made a decision, but you _seem_ to have made it on faulty
assumptions:

1)  You will have demand for layer 1 connectivity sufficient to offset the
higher costs of home running all the fiber both today and in 10 years.

2)  Not home running creates limitations, mainly on assumption #1, that
make it untenable.

If #1 isn't true (and I strongly doubt it is) then #2 can't be either.
 That doesn't mean that home running is wrong for you, but if you did your
math on those two assumptions then its certainly questionable.



>
>
>
> >                                              Almost all businesses want
> > INTERNET connectivity at the highest quality & speed at the lowest
> > cost and that's it. There are a small percentage, mainly larger
> businesses,
> > that do have special requirements, but those special requirements very
> seldom
> > include a L1 anything.
>
> Yes, but now we're into Whorf's Hypothesis: your vocabulary limits the
> things you're *able* to think about; it hasn't been practical to *supply*
> MAN L1 fiber at reasonable prices until about now.
>
>
I'm basing my views on talking to ISPs around North America and beyond and
helping them plan their networks.  You're basing your view on?  I could
certainly be wrong and it wouldn't be the first time nor will it be the
last.  Having said that, if you don't have some solid market research or
some interested ISPs telling you what they want exactly what are you basing
your opinion on?



>
>
> Sure, and I don't expect to sell a lot of it up front, unless my launch
> ISP wants to use their own L2 gear.  *But this does not preclude my
> building
> to enable it*, which is a different thing from how much of it I expect to
> sell.
>
>
If costs were identical I'd agree, but they're not.  Again, I'm not saying
that your situation is wrong for home running cable.  I'm simply saying you
should be looking at the costs of remote cabinets versus the cost of home
running and NOT a product that you don't expect to sell.



>
> Yep, and PR is not foreign to me; it will actually be in the project
> budget, along with outside counsel.
>

Let me know when you guys are ready and we'll be glad to send some traffic
your way.


>
>
> Oh, Jesus; Scott.  I've been clear from in front that this is a 36 months
> to
> shovel project for me; no, I haven't talked to providers yet; I'm still
> angling for the *job*.
>

But you're convinced you have the right architecture?  This dichotomy seems
odd to me.



>
> And yet, you didn't answer the question: *how many places has the choice
> about which you express an opinion *actually been made* by an ISP
> serving subs on a fiber plant they don't own, if any*?
>

Very few in the US.  In Europe its more common, but even where its
available as the commentator from France asserted, its only the largest
ISPs that take that route and its not always smooth.  In most places where
I've been involved open access was done on either cable or DSL networks.
 Doing it in DSL, which has something like 90% of the open access market,
is straightforward via PPPoE at layer 2.  In DOCSIS its also done at layer
2 because of how cable modems work (they look at each downstream signal).



>
>
>
> But that, Scott, is orthogonal to *whether they can work with my L1 guy(s)
> to find a problem*; a CC?? is not necessary for that, that I can see.
>
> And anybody big enough to want to come in and do L1 fiber *will already
> have guys who are fiber-trained*.
>

The problem here is the economics.  Its not a case of can I make it work,
you can.  Its a problem of do I make money (or at least break even) when I
make it work.  I'll posit that your L1 connections will require more time
from your technicians while you're taking in less revenue.  Are you going
to pre-qualify your L1 partners?  How?



>
>
> I've been avoiding LinkedIN like bubonic plague.
>

Its a good resource, since most people entering the field don't know what
mailing lists are much less Usenet or IRC...../em grumbles about young
whippersnappers



> > The last 20 yards are the most problematic and most changed. This is
> where
> > the installer matters most and why even good plant has bad installs.
>
> Sure.  But see way above about "install contractor testing to the jacks".
>
> Or, immediately below.  :-}
>
> > > Second, since we'll be terminating all 3 pairs to a jackbox, the
> > > installation contractor will be able to perform and document whatever
> > > acceptance testing we instruct them to. Sure, that will cost some
> > > more money, but again, if your capital plant is tested good when
> > > installed, this reduces markedly the opex maintenance cost over time.
> Where
> > > that breakeven point will be depends on what they want to charge me to
> do
> > > the testing, just as it does with Cat6.
>
> No comment there?
>

So your L1 partners will have to have a PON tester as well....you are
selective.


>
> > > [ Scott: ]
> > > > >> Sure it does, even in greenfield and whats more it costs more
> > > > >> over the
> > > > >> long term UNLESS you know where every home and business will be
> > > located 10
> > > > >> years from now.
> > >
> > > A luxury I do have, since my city is nearly 100.0% built; it's
> > > certainly 100% platted.
>

A side note, what happens when you need more than 3 pair to each jack?  How
are you building to MDUs, assuming you have some in the area?  What happens
if a new apartment complex is built next year?



>
> Perhaps.  But we seem to have established that homerun vs, say, GPON with
> splitters in the plant, is merely delta; maybe 5-8% more CAPEX.  And the
> other alternative you present, ring with active muxes in the field, I
> have already ruled out for the reasons above.
>
> Until I get to the point where I have real, current, quoted numbers on
> the plant install in various approaches, I suppose we ought to let
> this thread drop for now.
>

Probably a good idea, I had actually assumed from the thread you were past
that point.


>
> Cheers,
> -- jra
> --
> Jay R. Ashworth                  Baylink
> jra at 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
>
>


-- 
Scott Helms
Vice President of Technology
ZCorum
(678) 507-5000
--------------------------------
http://twitter.com/kscotthelms
--------------------------------



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