Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: PMD discussion


Probably for our focusing on PMD issue of 5-PMD or 3-PMD, our discussion of
serial vs. WDM will not help our course.  I will minimize our discussion;
however, I will re-state the key point.

The new code 64b/66b is made to reduce the bit rate from 12.5 Gbps to
10.3125, which is great.  However, nothing is free.  The bit rate reduction
is achieved at the expense of very unusual complex technique to achieve it.
Dynamically, continuously adjusting the data contents. To test, and analyze
the performance of a system is not an ordinary job.  The standard process of
using logic analyzer to analyze the logic waveform will be so dynamic from
one after another; as a result, one has to analyze the whole system of data
transfer and receiving to understand the significances of the waveform and
system performance, which is quite a new process.  Unless, you have
delivered a system before, you may not appreciate the complexity ahead.


Edward S. Chang
NetWorth Technologies, Inc.
Tel: (610)292-2870
Fax: (610)292-2872

-----Original Message-----
From: owner-stds-802-3-hssg@xxxxxxxx
[mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Chris Simoneaux
Sent: Friday, June 02, 2000 3:03 AM
To: Edward Chang; Jack Jewell; 'Ken Herrity'; '802.3ae'
Subject: RE: PMD discussion


If we are considering troubleshooting of serial vs WDM, we should also
consider how the optical link is troubleshooted (or troubleshot?).  This, as
far as I can tell, is a big unknown.  Especially as we are talking about
potentially multiple vendors with multiple ways of optically mux'ing and

Maybe someone can shed light on this.


-----Original Message-----
From: Edward Chang [mailto:edward.chang@xxxxxxxxxxxxxxxx]
Sent: Thursday, June 01, 2000 8:24 AM
To: Jack Jewell; 'Ken Herrity'; '802.3ae'
Subject: RE: PMD discussion


All 2.125 Gbps, 4.25 Gbps, and OC48 2,5 Gbps VCSELs are basically the same
GbE VCSEL technology with some modification.  The Fibre Channel 2.125 Gbps,
and 4.25 Gbps specifications are based on 1.0625 VCSEL characteristics with
the power budget shriks inversely proportional to the data rate increase.
Of course, it needs some revisions, but not a new technology at all.  The
WDM has been in the market for over 10, 15 years already.  Based on the
March OFC show, there were over 10 to 20 WDM vendors to serve industry.
Users can count on the maturing WDM technologies to provide parts.

I also support serial approach, which has different advantage from CWDM.  We
should keep working to make the advantages of each technologies shinning to
serve market.

For the serial PMD, the new coding scheme, 64b/66b is so complex, it will
give the system people
headache to trouble shoot a system.  When the excessive error occurs, the
ordinary logic analyzer will be useless to identify the cause of errors from
the waveform.  The 64b/66b code has too much dynamic features, which will
cause difficulties in finding the cause of a problem.


Edward S. Chang
NetWorth Technologies, Inc.
Tel: (610)292-2870
Fax: (610)292-2872

-----Original Message-----
From: owner-stds-802-3-hssg@xxxxxxxx
[mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Jack Jewell
Sent: Wednesday, May 31, 2000 6:08 PM
To: 'Edward Chang'; 'Ken Herrity'; '802.3ae'
Subject: RE: PMD discussion


The components you describe are NOT Gigabit Ethernet technologies.  They are
double speed and multiplied in number.  I am well aware of the existance of
2.125 and 2.5 Gbps VCSEL products. Picolight has been making 2.5Gbps oxide
VCSELs for a long time and demonstrated 2.125Gbps transceivers over a year
ago.  Your message addresses ICs only.  Are they multiples of discrete ICs
or quad versions?  Either way, there is little doubt that the ICs are
readily available.  That's fine.  But packaging and optics are the harder
issues.  They are NOT trivial and are compounded in a
multiple-source/detector package, especially multi-wavelength packages. And
the optical subassembly is still the largest cost component, even in
single-channel Gigabit transceivers.


-----Original Message-----
From: Edward Chang [mailto:edward.chang@xxxxxxxxxxxxxxxx]
Sent: Wednesday, May 31, 2000 2:55 PM
To: Jack Jewell; 'Ken Herrity'; '802.3ae'
Subject: RE: PMD discussion


The C/WWDM use the same technologies as the Gigabit Ethernet technologies.
It is not a new technologies to bear the concerns of risks.  The 8B/10B
Encoder/Decoder, and SERDES at 2.0 Gbps is already in the market for Fibre
Channel products, and to move up the data rate to 3.125 Gbps are just
another revisions of the field proved technologies, but not a new
technologies requiring test data and field tests to prove its feasiobility.

The 850 nm VCSEL at 3.125 Gbps, basically, is the same 850 VCSEL widely used
in networking  industry including, GbE, Fibre Channel, ATM...., which has
been proved by market already.
The 2.5 Gbps 850 VCSEL is already in the market.

Those are reasons that CWDM is low cost, and will be ready for market
introduction soon.


Edward S. Chang
NetWorth Technologies, Inc.
Tel: (610)292-2870
Fax: (610)292-2872

-----Original Message-----
From: owner-stds-802-3-hssg@xxxxxxxx
[mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Jack Jewell
Sent: Wednesday, May 31, 2000 2:08 PM
To: 'Ken Herrity'; '802.3ae'
Subject: RE: PMD discussion


Sorry for the misunderstanding.  The statement about 10Gig serial ICs stands
alone.  The last sentence regarding "broad-based support" refers to multiple
companies demonstrating working links, optical subassemblies, etc. and
providing detailed measurements to support the feasibility.  In that
context, I believe the statement is accurate.


-----Original Message-----
From: Ken Herrity [mailto:kenh@xxxxxxxxxxx]
Sent: Wednesday, May 31, 2000 10:34 AM
To: '802.3ae'
Subject: RE: PMD discussion


With regards to your second point:

"IC issues are nearly equal for all 3 serial approaches.  But neither of the
WDM solutions have anywhere near this level of broad-based support."

Blaze is currently working with 10 IC companies that either currently have,
will have or are planning to make chip sets to support the WDM solutions.

Best regards,


-----Original Message-----
From: owner-stds-802-3-hssg@xxxxxxxx
[mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Jack Jewell
Sent: Tuesday, May 30, 2000 6:14 PM
To: '802.3ae'
Subject: RE: PMD discussion


Your comments are well taken, though I feel compelled to comment on some of
them.  All in the spirit of building a clearer picture so that transceiver
vendors and system vendors can make a better decision soon.  Following your

1) Parallel solutions do not appear destined for 802.3ae adoption.  A serial
solution seems most suitable for this space.

2) Sooner or later everyone has to upgrade.  I don't see any proposals to
support 100's of meters of copper wire for 10GbE.  But I won't try to tell
you if this is the right time or not to recommend your customers to pull
upgraded fiber.  And I agree, the merits of choosing SMF for that upgrade
are very strong.
	Since Picolight demonstrated a working 10Gig transponder at the the
Networld & Interop tradeshow, I must disagree that "they are all
demonstrations of upgrades to technology and products customers already have
installed."  No offense taken since it was a recent demo.  However,
excluding parallel solutions which are not destined for 802.3ae adoption, it
is clear that the 850nm serial solution has the greatest "broad-based
support" in terms of feasibility demonstrations of any 10GbE candidate PMDs.
The serial 1310 and 1550 approaches also have a great deal of realness since
they also exist in the telecom market.  IC issues are nearly equal for all 3
serial approaches.  But neither of the WDM solutions have anywhere near this
level of broad-based support.

Hope you don't mind if the last comment went beyond responding to your


-----Original Message-----
From: Bruce Tolley [mailto:btolley@xxxxxxxxx]
Sent: Tuesday, May 30, 2000 3:58 PM
To: Cornejo, Edward (Edward); '802.3ae'; 'Jack Jewell'
Subject: RE: PMD discussion


As far as I am concerned comparing 850 nm WDM with 1310 nm WDM is like
comparing apples and oranges because they no not address the same customer

My customers want to run 10 GbE in the following spaces:

1) Very, very short reach for connections between switches in the same
room. For this application,parallel solutions seem to work fine

2) Building backbone on installed 62.5 micron MM fiber. For this
application, only one proposal works: 1310 nm WDM
There is no threshold of pain in regard to cost, since if I cannot sell to

The 850 nm WDM PMD could cost 1/10 that of the 1310 nm part but that does
me no good because the market is much smaller.

Even if there were a substantial cost difference, because I expect cost to
be a function of the experience curve, and the costs of the 1300 nm WDM to
come down as volume ramps.

And volume should ramp more quickly for a part that supports  the installed
base of 62..5 MM fiber.  Remember, customers resist FORKLIFT UPGRADES.  If
you examine all the demonstrations to date of 10 gbE technology at trade
shows, they are all demonstrations of upgrades to technology and products
customers already have installed.  This is no accident. We must support the
installed base to have this market take off quickly.

And by the way, if I am going to recommend new fiber for future proofing, I
might as well recommend SM fiber.

3) Medium long reach ( 10 to 40 km). Several PMDs cover portions of this
spectrum. 1300 nm serial seems most optimal.

4) Very long reach (over 50 km).  1550 nm serial seems the most optimal.

Thanks for listening


Bruce Tolley
Enterprise Line of Business
Cisco Systems

At 03:25 PM 5/30/00 -0400, Cornejo, Edward (Edward) wrote:

>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
> > leave at least one objective being greatly under-optimized.  I would
> > 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
> > optimal solutions for each Objective.  Given the concensus that the 2km
> > and
> > 10km objectives are best served by a common PMD, we are really
> > 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
> > with new fibers.  An interesting comment was made last Thursday
> > 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
> > 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
> > I
> > apologize.]
> >
> > Cost "Survey"
> > There have been several comments today regarding costs of different
> > The cost comparisons which I (and Paul K) presented were NOT the result
> > 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.)
> > 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.
> > 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
> > choice of PMDs; rather my company's choice of PMDs is based on a hard
> > of the markets and technologies required to address them in an
> > 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
> > meeting. I've sent my presentation to David Law, so it should be
> > on the web site in the next couple of days.
> >
> > In listening to the discussion after my presentation and then going
> > and talking to people, it feels to me like we're starting to converge.
> > there, yet, but making progress.
> >
> > The equipment manufacturers made it pretty clear they would like to see
> > 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
> > support the 3 PMD position if it is made clear which 3 PMDs the
> > oems want.
> >
> > Based on an informal straw poll and anecdotal evidence, my opinion is
> > 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
> > ___________________
> >