RE: [EFM] Active Architectures
Not if the multimode has a different color/cladding than the single mode
-=Francois=-
-----Original Message-----
From: owner-stds-802-3-efm@majordomo.ieee.org
[mailto:owner-stds-802-3-efm@majordomo.ieee.org] On Behalf Of Geoff
Thompson
Sent: August 21, 2001 2:01 PM
To: Horne, David M
Cc: 'Carlos Ribeiro'; stds-802-3-efm@ieee.org
Subject: RE: [EFM] Active Architectures
David-
I believe that you are overlooking the chief merit of the single fibre
(P2P
or P2mP) solution.
That is: The installer will have a much more difficult time getting it
wrong if there is only one fiber.
Having the cable-end appearance have a multi-mode and a single mode
would
destroy this advantage and increase the average termination time to:
1) Guess which fiber
2) Terminate that fiber
3) Test the termination
4) Aw #$%%*!
5) Got to step 1
Divided by 2
Geoff
At 07:20 AM 8/21/01 -0700, Horne, David M wrote:
>Hello Carlos, on your comment: "I see one immediate problem. I assume
>that the 850 nm lasers are coupled to multimode fiber, and that the
>downstream PON needs to use a singlemode fiber. If this is correct,
>then every home would have to be served by two fibers of different
>construction. I've heard news of fibers able to carry both single and
>multimode signals but haven't seen any hard data on this."
>
>Yes, that is why I made the below comment in my original message:
>"There are a couple options on the fiber between the node and the ONU
>but I'll leave that discussion for later."
>
>I don't think I'd use the word "problem" to describe it since it is
>quite solvable. It's more a question of which method is used. I would
>advocate the use of microtubing or conduit between the node and each
>ONU. That way, the fiber or fibers would only be installed (blown-in or
>pulled) when a subscriber signs up for service. Likewise, the ONU would
>only be installed at that time. It doesn't have to be done this way,
>but to do otherwise would leave the network operator with stranded
>assets in the field. In some cases these assets could sit idle for a
>very long time. Another option is the customer could own both the fiber
>and the ONU and have them installed by a third-party when they
>subscribe to a service. The second strand is still quite a minimal cost
>compared to the transmitter cost savings that the architecture
>provides. In a neighborhood of 1/4 acre lot sizes, the average run for
>a cluster of 16 homes would be about 170 meters or so.
>
>The extra fiber (if 2 are used) shouldn't be viewed as an additional
>cost per-se. It is just a part of the architecture decision and the
>OVERALL costs are what matter. It is easy to single out an
>architectural difference and concentrate on what that costs, as an
>argument against something, but in reality the big picture is what
>matters. Big-picture-wise, this apparent extra cost disappears.
>
>If a single fiber were used, I believe there are methods such that it
>could be either singlemode or multimode. Anyone who can provide cost
>and performance details of such an arrangement please do. I find very
>little published on this, except to imply feasibility. In any case I
>tend to think this would be more expensive overall than 2 separate
>fibers since mux and demux components are needed. It may be
>straightforward off-the-shelf components but I think those cost more
>than 170 meters of fiber.
>
>
>
>
>-----Original Message-----
>From: Carlos Ribeiro [mailto:cribeiro@mail.inet.com.br]
>Sent: Tuesday, August 21, 2001 4:16 AM
>To: Frank Coluccio; david.m.horne@intel.com
>Cc: sganguly@yahoo.com; ramu_raskan@angelfire.com;
>stds-802-3-efm@ieee.org
>Subject: Re: [EFM] Active Architectures
>
>
>(in the context of David Horne's "half-PON" idea)
>At 20:22 20/08/01 +0000, Frank Coluccio wrote:
> >For extremely long runs, have you considered the tradeoffs of an
> >inexpensive cwdm solution in lieu of multiple strands coming back
> >from the ONUs?
>
>That was my first thought when reading David's proposal. In fact I
>already discussed similar views not only with David, but with lots of
>people in this list. That's the main reasoning to develop a wavelength
>alocation plan that allows for the future use of C/DWDM. Gerry
>Pesavento is going to discuss this issue.
>
>As far as Mr. Horne proposal is concerned, I see one immediate problem.
>I assume that the 850 nm lasers are coupled to multimode fiber, and
>that the downstream PON needs to use a singlemode fiber. If this is
>correct, then every home would have to be served by two fibers of
>different construction. I've heard news of fibers able to carry both
>single and multimode signals but haven't seen any hard data on this.
>
>
>Carlos Ribeiro
>CTBC Telecom