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RE: PMD discussion

Jack, et al,

I could almost live with the list you have below, however, I thought Mr.
Tolley mentioned the importance of the embedded base(62.5um) up to 300m. If
this is the case, I would change the WDM from the 850 to 1310 window. The
only issue is cost between the two WDM solutions and I am sure there is a
difference, but by how much? 

Also, systems folks need to tell us what their threshold of pain is for
delta differences in cost. Is it 10%, 15%, 20% or 25%(0% is not an option,
sorry). This could make our decision easier.


> ----------
> From: 	Jack Jewell[SMTP:jljewell@xxxxxxxxxxxxx]
> Sent: 	Tuesday, May 30, 2000 2:59 PM
> To: 	'802.3ae'
> Subject: 	RE: PMD discussion
> Walt (and others who have responded in the interim),
> Although I am encouraged that the group will come to some agreement
> without
> delaying our schedule, there is still some way to go.  Given the breadth
> of
> the 5 objectives set forth, it seems almost certain that a 3-PMD set will
> leave at least one objective being greatly under-optimized.  I would hate
> for that to be the highest volume product.  Following the theme of
> optimizing for each space presented Thursday by Steve Haddock (and
> departing
> from his presentation of only 3 spaces), I would see the following as the
> optimal solutions for each Objective.  Given the concensus that the 2km
> and
> 10km objectives are best served by a common PMD, we are really discussing
> 4
> distinct Objectives.  Most of the debate is focused on the
> shorter-distance
> objectives, so this note focuses on them.  I recommend the 4-PMD set
> below.
> SMF up to 40km - 1550nm Serial
> SMF up to 10km (incl 2km) - 1310nm Serial
> MMF up to 300m - 850nm Serial
> Installed MMF up to 100m - 850 CWDM
> Highest Volume Product Space
> The highest-volume product space here is almost certainly the MMF up to
> 300m.  This is due to most of the transceivers being put into new products
> with new fibers.  An interesting comment was made last Thursday regarding
> 100Mb Ethernet in which 3 PMDs were spec'd in order to accommodate TX
> grade
> cable as well as the installed base of T2 and T4 cable.  Subsequently the
> T2
> and T4 were more or less abandoned and virtually the entire market went
> for
> the TX-based PMD.  [I did not participate in that process; this is my
> interpretation of the comments made last Thursday.  If this is inaccurate,
> I
> apologize.]
> Cost "Survey"
> There have been several comments today regarding costs of different PMDs.
> The cost comparisons which I (and Paul K) presented were NOT the result of
> an "unscientific survey."  They are the average of estimates which were
> circulated on the reflector.  No one was excluded from presenting their
> own
> numbers.  I believe a great deal of thought was put into each estimate.
> Are
> the numbers accurate? Of course not.  Are they all consistent enough to
> represent the general picture (which is how they were presented)?
> Absolutely.  They have been presented publicly and privately with no
> voiced
> disagreement.  
> Relative Costs of Serial and WDM
> It has been suggested and sometimes even stated outright that a WDM
> solution
> will be as low-cost or even lower-cost than a serial solution.  This is
> unsupportable.  I put this question to (and look for responses from)
> vendors
> who have manufactured and sold transceivers in any reasonable volume.
> (These are the ones who know transceiver costs better than anyone.)  Does
> your optical subassembly cost more than your ICs?  In expectation of a
> unanimous "Yes" to that question, comes the next question.  In order to
> move
> to higher performance levels while minimizing the cost increase should
> you:
> 1) increase the complexity of your optics; or 2) increase the complexity
> of
> your ICs?  This is why we aren't seriously discussing a WDM-only set of
> PMDs.  WDM is a good way to get more data over a fiber than otherwise
> possible - but it's used only when simpler approaches cannot be used.  As
> for the ICs, there were a lot of IC vendors at the meeting having
> aggressive
> goals and impressive capabilities.  Assuming a "market entry" for 10GbE
> products at the end of this year, it is reasonable to forecast that the
> cost
> to produce a serial product will be less than its equivalent WDM product
> at
> the time of market entry or within 6 months after that.  I.e. for
> essentially the entire product lifetime.
> The 4 PMDs recommended above are not biased in order to favor my company's
> choice of PMDs; rather my company's choice of PMDs is based on a hard view
> of the markets and technologies required to address them in an economical
> fashion.
> Jack
> -----Original Message-----
> From: Walter Thirion [mailto:wthirion@xxxxxxxxxxxx]
> Sent: Sunday, May 28, 2000 11:58 AM
> To: '802.3ae'
> Subject: PMD discussion
> 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
> ___________________