Re: Muni fiber: L1 or L2?

[Scott Helms <khelms () zcorum com>]

> > 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.
>
> That's my fundamental design assumption, and you're the first person to
> throw a flag on it.  I'm hearing $700 per passing and $600 per sub; those
> seem sustainable numbers for a 30 year service life amortization.
>
> I'm not yet 100% clear if that's layer 1 only or layer 2 agg as well.

OK, think about it like this.  The most efficient topology to provide both
coverage and resiliency is a ring with nodes (shelves) from which end users
are connected.  That ring (usually Gig or 10Gig Ethernet today) needs to be
connected to a central location so you can interconnect to other providers
(your ISP customers) and/or to connect to the Internet if the city is also
going to provide direct L3 services.  If you instead push down a L1 path
then the most expensive pieces of gear in the access network (the FTTx
shelves) have to be replicated by everyone who wants to offer services.
 This bad not just from the initial cost perspective but because people and
companies that identify themselves as ISPs seldom know anything beyond
Ethernet and IP and then only in a few manufacturers (mainly Cisco and
Juniper).  They are most certainly not comfortable working with Calix,
Adtran, and the rest of the carrier (formerly telco) equipment
manufacturers.  To make matters more complicated in cases of problems you
don't have a good demarcation of responsibility.  What do you do as the L1
provider when one of your ISP partners tells you one of his customers can't
connect or stay connected to that ISP's gear?  Whose responsible in that
case?  What happens when your tech goes out with an OTDR (
http://en.wikipedia.org/wiki/Optical_time-domain_reflectometer) meter and
says the connection is fine but your ISP insists its your problem?


> [ And note that for me, it's practical; most everyone else is merely
> along for the ride. ]
>
> >       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.
>
> You're talking about what I'm calling L2 clients.  If layer 2 falls over
> it's my fault, and believe me, I'll know about it.

What I'm telling you is that you can't reliably have L1 clients in shared
model.  You can of course lease someone a dark fiber from point A to point
B, but that's not a traditional way of partnering with ISPs and in any case
will only be feasible for a small number of connections since you
(probably) can't afford to home run each location in your network.

> > 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.
>
> You just changed gears again, no?
>
> I'm not trying to share L1 *drops*.  I'm trying to make it possible
> to share *the entire L1 deployment between providers*, a drop at a time.

That's what I'm trying to tell you can't do.  Its more expensive in both
the initial and long term costs.

> > 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.
>
> Depends on what you're trying to do.  But yes, I do know the difference
> between CAPEX and OPEX.
>
> Cheers,
> -- jra
> --
> Jay R. Ashworth                  Baylink
> jra () 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
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http://twitter.com/kscotthelms
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