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RE: [EFM] Active Architectures

Not if the multimode has a different color/cladding than the single mode

-----Original Message-----
[] On Behalf Of Geoff
Sent: August 21, 2001 2:01 PM
To: Horne, David M
Cc: 'Carlos Ribeiro';
Subject: RE: [EFM] Active Architectures


I believe that you are overlooking the chief merit of the single fibre
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
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


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; 
>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