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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
> > ___________________
> > 
> > 
> >