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@xxxxxxxxxxxxxxxx]
>Sent: Tuesday, August 21, 2001 4:16 AM
>To: Frank Coluccio; david.m.horne@xxxxxxxxx
>Cc: sganguly@xxxxxxxxx; ramu_raskan@xxxxxxxxxxxxx;
>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