Muni network ownership and the Fourth

Leo Bicknell bicknell at
Wed Jan 30 04:10:23 UTC 2013

In a message written on Tue, Jan 29, 2013 at 07:46:06PM -0800, Owen DeLong wrote:
> Case 2, you move the CO Full problem from the CO to the adjacent
> cable vaults. Even with fiber, a 10,000 strand bundle is not small.
> It's also a lot more expensive to pull in 10,000 strands from a few
> blocks away than it is to drop a router in the building with the MMR
> and aggregate those cross-connects into a much smaller number
> of fibers leaving the MMR building.
> But what happens when you fill the cable vaults?

It's really not an issue.  10,000 fibers will fit in a space not
much larger than my arm.

I have on my desk a 10+ year old cable sample of a Corning 864
strand cable (36 ribbons of 24 fibers a ribbon).  It is barely
larger around than my thumb.  Each one terminated into an almost-full
rack of SC patch panels.

A web page on the cable:

My company at the time build a duct bank by building 6x4" conduit,
installing 3x1.25" innerduct in each conduct, and pulling one of
those cables in each innerduct.  That's a potential capacity of
15,525 fibers in a duct bank perhaps 14" wide by 8" tall.

A "vault" as used for traditional telco or electrical (one big
enough for a man to go down in) could hold millions of these fibers.
They were never used, because they were way too big.  There's also
plenty of experience in this area, telcos have been putting much
larger copper cables into CO's for a long time.

Were there demand, they could easily put more ribbons in a single
armored sheeth.  The actual stack of fibers is about 1/2" wide and
3/8" thick for the 864 strands.  You could extrapolate a single
10,000 strand cable that would be smaller than the power cables
going to a typical commercial transformer.

The cost of fiber is terminating it.  Running 864 strands from one
end of a colo to another inside, compared with running it a block
down the street isn't significantly different; modulo any construction
costs.  Obviously if it costs $1M to dig up the street that's bad,
but for instance if there is already an empty duct down the street
and it's just pulling cable, the delta is darn near zero.

That's why I think rather than having the muni run colo (which may
fill), they should just allow providers to drop in their own fiber
cables, and run a fiber patch only room.  There could then be hundreds
of private colo providers in a 1km radius of the fiber MMR, generating
lots of competition for the space/power side of the equation.  If one
fills up, someone will build another, and it need not be on the same
square of land....

       Leo Bicknell - bicknell at - CCIE 3440
        PGP keys at

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