Re: PMD discussion
[Date: 05/29/2000 From Seto]
Dear Brian,
Thanks for your clarification. I look forward to your evaluation result in
July. I'm sure you are aware that I'm not at all against 1310nm-WWDM proposal.
BTW, I assume your team has a lot of experience with 850nm-WWDM solution. I
believe you once had a 850nm-WWDM lab prototype (per Mr. Dolfi's presentation
in 3/1999). Would you provide your insight on the argument on 850nm-serial vs.
850nm-WWDM? Do you think there would be a potential laser eye safety issue
in 850nm-WWDM proposal as suggested by Jonathan?
Seto
>
> Dear Seto,
>
> No offense taken. There should be no problem going 10 km over single mode
> fiber with the same module that is optimum for going 300 m over MMF. I
> expect that a full set of link results will be presented in July, to provide
> the physical evidence you are looking for. Until then, you'll have to trust
> the link model.
>
>
> As for relative cost, most people believe that WWDM will be cheaper than
> serial in the short term and that in the long run, serial will be cheaper.
> The debate seems to be over when the two will cross. Some believe it will be
> as soon as 2 years from now, while others believe it will be 3 or 4 years
> from now. The 1.8x and 3.0x numbers you are referring to have no basis,
> other than an unscientific survey among a very small sample (I believe the
> number of survey respondents was 4) of serial PMD advocates.
>
> Since companies that are actually developing serial and WWDM products for
> sale usually choose to keep their cost models to themselves, it will be
> difficult to establish relative cost until products hit the market. Even
> then, selling price and cost are two different things!
>
> - Brian Lemoff
>
> -----Original Message-----
> From: Seto, Koichiro [mailto:seto@xxxxxxxxxxxxxxxxxxxx]
> Sent: Monday, May 29, 2000 7:25 AM
> To: wthirion@xxxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> Subject: Re: PMD discussion
>
>
>
> [Date: 05/29/2000 From Seto]
>
> Walter,
>
> My understanding is that the following set is also one of the top favorites:
>
> ________________optimized for may be used for
> 1310 nm WWDM MMF upto 300m SMF upto 10km
> 1310 nm Serial SMF upto 10km MMF upto 86m
> 1550 nm Serial SMF upto 40km
> ________________
>
>
> I understand there are some risks that 850nm-WWDM solution may not satisfy
> laser eye safety as Jonathan pointed out in the discussion on Thursday.
> Also, I learned that there are some risks that 1310nm-WWDM may not be able
> to achieve 10km at SMF if not impossible. At least we have not seen any
> data that would prove the feasibility of 1310nm-WWDM over 10km SMF. It is
> not to say that this can not be done, but I have not been convinced that the
> same 1310nm-WWDM optics at same cost factor will serve for both 300m MMF
> and 10km SMF. Also, some people pointed out that 1310nm-Serial can be built
> at cost factors of x1.8 to 850nm-Serial while 1310nm-WWDM is x3. If we can
> achieve the same goal (SMF 10km), the cheaper is the better.
>
> I hope no one is offended by my not-so-educated opinion. I would appreciate
> a healthy discussion.
>
> Seto
>
> >
> > First of all, thanks to everybody that presented PMD proposals at the last
> > meeting. I've sent my presentation to David Law, so it should be available
> > on the web site in the next couple of days.
> >
> > In listening to the discussion after my presentation and then going around
> > and talking to people, it feels to me like we're starting to converge. Not
> > there, yet, but making progress.
> >
> > The equipment manufacturers made it pretty clear they would like to see no
> > more than 3 PMDs in the standard. The PMD vendors have some concern that
> > using only 3 PMDs may sub-optimize certain objectives, however, they could
> > support the 3 PMD position if it is made clear which 3 PMDs the equipment
> > oems want.
> >
> > Based on an informal straw poll and anecdotal evidence, my opinion is the
> > first choice would be the set:
> > ________________
> > 850 nm WWDM
> > 1310 nm WWDM
> > 1550 nm Serial
> > ________________
> >
> > If that set isn't feasible, then the 2nd most popular choice is:
> > ________________
> > 850 nm WWDM
> > 1310 nm Serial
> > 1550 nm Serial
> > ________________
> >
> > Thoughts, feedback?
> >
> > Walt
> > ___________________
> > Walter Thirion
> > Chair, IEEE 802.3ae PMD Sub-Task Force
> > 301 Congress Ave.
> > Suite 2050
> > Austin, Texas 78701
> > Voice: 512-236-6951
> > Fax: 512-236-6959
> > wthirion@xxxxxxxxxxxx
> > ___________________
> >
> >
> >