RE: PMD discussion
Seto,
I agree that the 3 PMD set you described in your first paragraph was the
original favorite set(okay unofficially). One additional comment is that the
1550nm serial can be extended to 60 or 80km with new SMF, dispersion
compensation(active or passive), or optical amplification. The justification
for these 3 PMD's were one optimized for legacy MMF support up to 300m(WWDM
1.3um), lowest cost SM(1.3um DFB) up to 10km, and 1550nm for long reach.
All- Having said the above, I also feel compelled to include an 850nm
solution. The only question I have is how and which one(s), and can we still
keep it at three. I am thinking out loud now, and here is some information
that may get us heading in the right direction. I am using cost factors
tabulated by Jack Jewel, which are views from varying points. Of the four
individuals, one is biased longwave serial and WDM, two are shortwave, and
one is a dont care.
For Legacy Multimode up 100m:
* 850nm CWDM(1.94 of GE LX)
* Reference Paul Kolesar statement "850nm CWDM cost claims
competitive with 850nm Serial"
* Uncooled 1310nm DFB or FP with equilization to ~200m or w/o
equilization to ~85m. Also, in some applications the external mode
conditioning patchcord may be required.(2.46)
Note: No MAS solutions included because they are currently not part of this
discussion.
For Legacy MMF up to 300m:
* 1310nm WWDM(3.43). Note: As Brian mentioned, the cost factor is
questionably high in the near term.
For new MMF up to 300m:
* 1310nm WWDM(3.43) Note: Same as legacy comment.
* 850nm Serial(1.94)
* 850nm CWDM(1.94)
For SMF up to 10km:
* 1310nm Serial(2.46)
* 1310nm WWDM(3.43)
For SMF up to 40km:
* 1550nm cooled
* 1310nm cooled w/ APD(?)
My understanding is that the 100m(equip. room) and 300m legacy MMF are the
highest volume applications, and the most cost sensitive. For 100m, either
CWDM or 1310 serial could suffice. Both need a little help to get to 100m,
but they should be able to cope. There seems to be some suggestions that a
premium will exist for the 1310nm, but I would observe(okay biased from my
view) that volume will reduce this gap to the point that it gets into the
wash. For 300m, the only legacy solution is 1310nm WWDM.
I will also observe that there is evidence that new MMF fiber is being
installed, so we should have a solution that takes cost advantages of the
PMD's that support this high bandwidth fiber. These would include any 850nm
solution. I am leaning towards serial because it seems the costs are the
same as CWDM, but the complexities are not. Also, we already have a longwave
WDM solution for future upgrades(40Gbps or 100GE).
I am not sure this is making any sense, but here is my conclusion:
* 1310nm WWDM(optimized for legacy MMF up to 300m)
* 1310nm serial(optimized for SMF up to 10km)
* 850nm serial(optimized for short reach, lowest cost and complexity)
* 1550nm serial(Optimized for long reach)
I could be pursuaded to exclude the 1550nm PMD and have a pointer in the
standard to the ITU where these spec's are defined. The only issue is speed
for LAN applications. I'll have to give this some more thought.
I could also be pursuaded to swap in 850nm CWDM instead of 850nm serial, if
the 850nm camp and systems integrators feel this makes the most sense.
Regards,
Ed C. LU-Opto
> ----------
> From: Seto, Koichiro[SMTP:seto@xxxxxxxxxxxxxxxxxxxx]
> Sent: Monday, May 29, 2000 10:25 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
> > ___________________
> >
> >
> >
>