Muni fiber: L1 or L2?

Leo Bicknell bicknell at ufp.org
Sun Feb 3 03:32:03 UTC 2013


In a message written on Sat, Feb 02, 2013 at 10:17:24PM -0500, Scott Helms wrote:
> Here's the thing, over the time frame your describing you're probably going
> to have to look at more fiber runs just because of growth in areas that you
> didn't build for before.  Even if you nail the total growth of homes and
> businesses in your area your chances of getting both the numbers right
> _and_ the locations are pretty slim. Also, you're going to have to replace
> gear no matter where it is core or nodes on a ring.  Granted gear that
> lives in a CO can be less expensive but its not that much of a difference
> (~1% of gear costs).  Having a ring topology is basically the best way
> we've come up with as of yet to hedge your bets, especially since you can
> extend your ring when you need.

I'm not sure I understand your growth argument; both models will
require additional build costs for growth to the network, and I
think they roughly parallel the tradeoff's we've been discussing.

As for the gear, I agree that the cost per port for the equipment
providing service (Ethernet switch, GPON bits, WDM mux, whatever)
is likely to be roughly similar in a CO and in the field.  There's
not a huge savings on the gear itself.

But I would strongly disagree the overall costs, and services are
similar.  Compare a single CO of equipment to a network with 150
pedistals of active gear around a city.  The CO can have one
generator, and one battery bank.  Most providers don't even put
generator with each pedistal, and must maintain separate battery
banks for each.  A single CO could relatively cheaply have 24x7x356
hands to correct problems and swap equipment, where as the distributed
network will add drive time to the equation and require higher
staffing and greater costs (like the truck and fuel).

Geography is a huge factor though.  My concept of home running all fiber
would be an extremely poor choice for extremely rural, low density
networks.  Your ring choice would be much, much better.  On the flip
side, in a high density world, say downtown NYC, my dark fiber to the
end user network is far cheaper than building super-small rings and
maintaining the support gear for the equipment (generators and
batteries, if you can get space for them in most buildings).

Still, I think direct dark fiber has lower lifecycle costs for 70-80% of
the population living in cities and suburban areas.

-- 
       Leo Bicknell - bicknell at ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
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