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Hello Isono-san,
In your email, you identify XLMD type TOSA
and ROSA as candidates for the GPPO IF optics. Can you provide the details of
the GPPO IF based ICs that you are proposing to use in a 40GE-Serial solution?
Is there any publically available information about 40G 4:1 SerDes ICs in a
GPPO IF package that are candidates for the 40GE 10km SMF PMD? Are there any
diagrams or photos of such 40G SerDes ICs that you could share? To date, no information
has been provided on such ICs to 802.3ba. The only new 40GE ICs that have been presented
to 802.3ba are advanced SerDes ICs in PCB RF IF packaging (GPPO-less). There has
been strong disagreement about the feasibility of this technology for volume
production in 2010. Further, such ICs are presumably not usable with the GPPO
IF based optics, and in any case only contribute to an additional factor of
1.3x cost reduction, so are much less relevant to the discussion. Thank you Chris From: Hideki Isono [mailto:isono@xxxxxxxxxxxxxx]
All, Date:
Mon, 11 Aug 2008 20:35:48 +0900 "urn:schemas-microsoft-com:vml"
xmlns:o = "urn:schemas-microsoft-com:office:office" xmlns:w =
"urn:schemas-microsoft-com:office:word" xmlns:st1 =
"urn:schemas-microsoft-com:office:smarttags"> ----- Original Message ----- From: Chris
Cole To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Sent: Friday, August 08, 2008 11:25 AM Subject: Re: [802.3BA] Discussion on 40G for ="" 10
km SMF Hello
Takai-san, As
confirmed in your latest email, we have now distilled the two key points of
disagreement about future 40GE-Serial cost. 1) The Serial proponents project an 8x cost reduction for GPPO IF
based 40G Modules in two years (by 2010) if 40GE-Serial is adopted as an IEEE
standard because this will increase the 40G-Serial volume by 10x to 20x,
triggering a large cost reduction investment for example in ICs. The
opponents do not foresee such an 8x cost occurring based on a 10x to 20x volume
increase. A more reasonable cost decrease is 2x to 3x, based on historical
trends and past experience with similar volume increases. 2) The Serial proponents project another 1.3x cost reduction by going
from GPPO IF based to GPPO-less IF based modules, with high volume (>100K)
shipment feasible in 2010. The
opponents generally agree with the 1.3x cost reduction, but see a much longer
period then 2 years (more like 5 to 8 years) to bring this difficult technology
to the market. There is
general agreement on 40GE-CWDM cost reduction timeline, as this is closely tied
to 10GE cost. Further
discussion is unlikely to change the minds of the proponents on either side of
the debate. However the key points are now clearly laid out for those that are
still in the process of making a decision. Chris From: Atsushi Takai [mailto:atsushi.takai@xxxxxxxxxx]
Sent: Thursday, August 07, 2008
6:36 PM To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] Discussion
on 40G for ="" 10 km SMF
Chris > A
general rule is that a 10x increase in volume results in 2x drop in cost. >
Therefore, it is very hard to see how the 8x cost drop in two years of GPPO IF
based 40G module can be justified by the projected 10x to 20x volume increase. As I
pointed that the biggest current cost eater is Si and cumulative volume is not
enough to compensate investment. If IC
vendor get volume that will be enough for investment, the IC cost will be
reduced rapidly. As you
know, the 40G market is growing rapidly and we are expecting the break point
sooner. This
drop may significant bigger than 2x per 10x volume.
=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~= Atsushi Takai =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
----- Original Message
----- From: Chris Cole To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Sent: Thursday, August 07,
2008 7:50 AM Subject: Re: [802.3BA]
Discussion on 40G for ="" 10 km SMF Hello
Isono-san, Thank
you for clarifying which set of cost numbers we should use for discussion. Your
email highlights a confusing point in the traverso_02_0708 presentation. The
conclusion for 2010 Serial (at 120K volume) is 1 x CWDM 2010 cost for GPPO IF,
and 0.78 x CWDM 2010 cost for PCB (GPPO-less) IF. The conclusion for 2010 CWDM
is 6 x 10GE LR 2010 cost. Lightcounting
data (see cole_04_708) gives the 2008 40G VSR module cost as 48 x 10GE LR 2010
cost (= 40 x 10GE 2008 LR cost.) This
means that there is an 8x reduction in cost from 2008 to 2010 for GPPO IF based
module, and an additional 1.3x (10x total) cost reduction for GPPO-less IF
based module. Page 16 of traverso_02_0708, identifies main drivers for this
drop in Serial 2010 cost: - Optics packaging - 4:1 SerDes instead of16:1 SerDes - Low cost SerDespackaging - Low cost RF interconnect - Higher Volume There is
an in-depth discussion of low cost GPPO-less IF packagingand interconnect
technology on pages 6, 7, 8, 9 and 10 of thepresentation, which supports three
of the above bullets. However, thisaddresses the 1.3x (of the 10x total) cost
reduction factor since itapplies to GPPO-less IF. This
leaves two other above bullets to account for majority of the 8xcost drop in
two years. There is
no specific discussion in the presentation of why a 4:1SerDes is cheaper then a
16:1 SerDes, although comments were made duringQ&A in This
leaves the Higher Volume bullet to account for the majority ofthe 8x cost drop
in two years, with page 13 giving the volume assumptionas 120K in 2010. In his
8/2/08 email, Takai-san estimated the cumulative40G shipment as 10K. This gives
a volume increase of 10x to 20x,depending on exact annual assumptions. A
general rule is that a 10x increase in volume results in 2x drop incost. Therefore,
it is very hard to see how the 8x cost drop in two yearsof GPPO IF based 40G
module can be justified by the projected 10x to 20xvolume increase. A much
more reasonable conclusion is that there will be a 2x to 3xcost drop in two
years, as projected in cole_08_0708, page 9, andtraverso_04_0308, page 8. Chris From: Hideki Isono [mailto:isono@xxxxxxxxxxxxxx]
Sent: Tuesday, August 05, 2008 7:58
PM To:
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx Subject: Re: [802.3BA] Discussion
on 40G for ="" 10 km SMF Alessandro-san Regarding the cost difference you pointed out, the background
reason isas follows. a) In this proposal timing, the
specific 40GE volume is not discussed,and also the existing technology adaptation is assumed. This is the
reason whythis estimation is too high. b) From this estimation, new
technology such as low cost TOSA/ROSA(XLMD) and also low cost SerDes package are
assumed. As the result of these assumption, the cost becomes very
close to thelatest estimation. C) From this estimation, the
specific volume (120K pcs for 2010) isassumed and GPPO-less package is optionally introduced. We
concluded that the cost is 0.78 xCWDM for GPPO-less and 1 x CWDM for GPPO IF. Estimation described in (C) is the
latest and the most accurate one. Please refer to this document hereafter. Best regards, Hideki Isono Fujitsu Ltd At 22:01 08/08/04 -0700, Hi Atsushi, > I am afraid that to chose 40GbE CWDM will ignore
data centerapplications that is cost sensitive and may require less than
4x10Gcost. or >"We have to resolve this to achieve <2x10G
cost." it is not clear how you derive the conclusion that 2X
is needed for thedata center space. Is it a gut feeling or is there a
rationalexplanation? At least below I attempted to articulate briefly why
4X if veryreasonable on the optics (which BTW is just a part of the total
systemcost) to ensure market success for 40G SMF and I would like to
understandif you have any specific disagreement: "I think ~4X the cost of 10G with *just* the
benefit ofconsolidating 4 metro fibers will work quite well. On top of it add the operational advantage of
simplifying the networkbyreducing the dependency on LAG by a factor of 4 and
one could arguethat4X on SMF is perfectly fine." Last I am now getting confused with this latest 2X 10G
cost on top ofallthe cost projections presented on 40G serial: a)
http://www.ieee802.org/3/ba/public/mar08/traverso_04_0308.pdf : 2012 Serial still more than 1X CWDM b)
http://www.ieee802.org/3/ba/public/may08/jewell_02_0508.pdf: 2011 Serial is 1X CWDM c)
http://www.ieee802.org/3/ba/public/jul08/traverso_02_0708.pdf 2010 Serial is 0.78X CWDM d) Now in 07/08 the claim is 2X 10GBASE-L which is
anywhere between0.5Xand 0.3X CWDM (even lower than traverso_02_0708 in 2012) Why the story keeps changing on serial? Thanks, Alessandro
> -----Original Message----- > From: Atsushi Takai [mailto:atsushi.takai@xxxxxxxxxx]
> Sent: Monday, August 04, 2008 5:48 PM > To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx > Subject: Re: [802.3BA] Discussion on 40G for
="" 10 km SMF > > Team > > First of all, in case of CWDM, volume will never
resolve the issue. > The cost will be always 4x10G+WDM. > The cost will go down according to 10G. > > I agree with Chris's comment that integration
will not > resolve the cost issue in case of 40GbE CWDM. > We also had experiences of such technologies and
found difficulties. > Thus in case of 40GbE CWDM, The cost seems
4x10G+(WDM). > > ((100GbE WDM is different. > In case of 100GbE WDM, the cost will be
considered almost 4x25G+(WDM). > Thus to achieve <10x10G cost is to achieve 25G
cost to be > closer to 10G. > We believe we can achieve it.)) > > It seems that CWDM has no way to achieve 4x10G
and may be 6x > with reasonable estimation. > I am afraid that to chose 40GbE CWDM will ignore
data center > applications that is cost sensitive and may
require less than > 4x10G cost. > > I agree that even 4x10G is much cheaper than
current cost of > 40G 2km serial. > But it is not the discussion point. > > In case of serial, volume and well-known
technology will > resolve the cost issue. > (1) Today's market is small, may be <
10K/year. > I
believe team confirmed market. > Also
carrier started to install 40Gbit/s transport > systems recently. > We
are receiving 40Gbit/s Infinibandthat is another market. > Volume
pulls the investment for thetechnology and it is > happening. > (2) Optical device companies that I discussed
have no concern > on technology. > Especially
this is 1310-nm transmission. > (I
hope you understand this is very important) > (3) IC cost is always related volume to
compensate investment. > (4) Thus only big challenging technology is
interconnection > technology. > We
have to resolve this to achieve<2x10G cost. > This
is the interconnection betweendriver to Laser module > with
the length of about 1 inch orless > that
40G signal go from driver chip tolaser chip. > We
have resolution today semi-ridgedcoaxial cable. > However
we need low cost alternativeto achieve such low cost. > We
may overcome using customizeddesign with IC and module. > However
we need universal design toreduce cost and wide usage. > Anyway
I am optimistic for this. > > I believe we have to choose serial. > > > =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~= > Atsushi Takai > Marketing Division, Opnext Japan, Inc > > =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~= > ----- Original Message ----- > From: " > To: <STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx> > Sent: Tuesday, August 05, 2008 8:00 AM > Subject: Re: [802.3BA] Discussion on 40G for
="" 10 km SMF > > > Hi Frank, > I have a couple of brief of comments inline... > > > Steve; > > > > I share with your viewpoint, but still have
similar concerns, > > so put us in the category of
"undecided" regardingthis after > > listening to customers from either datacom
or telecomside. > > > > The problem is if neither 40g serial or 4x10
CWDM canprovide > > a cost trend more favorable than 4x
individual 10ge, then > > 40gbe will be hard to take off, everyone may
stick to install > > I think ~4X the cost of 10G with *just* the
benefit of > consolidating 4 metro > fibers will work quite well. > On top of it add the operational advantage of
simplifying the > network by > reducing the dependency on LAG by a factor of 4
and one could > argue that 4X > on SMF is perfectly fine. > > > 10ge a bit longer, especially for data
centers (which is more > > cost sensitive), so 40gbe SMF may eventually
unable to build > > up significant volume. Think about the 10gbe
volume > > difference regarding LX4 vs. 10ge serial. > > Comparing the volumes of optics destined to
different > applications is not an > apple-to-apple comparison. Even though LX4 works
on SMF, I > believe less than > 5% use it for that purpose. > > Thanks, > Alessandro > > > > 4x10g CWDM option may provide a competitive
cost point from > > day one, are we underestimating the LX4 mfg
issues in terms > > of photonics integrated circuits to drive
further cost down? > > > > Are we too optimistic on 40g innovation for
cost reduction > > (obviously maybe lengthy and expensive
development) keeping > > in mind close to limits of current
electronics? > > > > Feel like both 4x10g CWDM and 40ge serial
face "breakthrough" > > ahead. Without any reasonable/realistic
consensus with these > > "hard" data, seems there would be
difficult for thegroup to > > reach the decision unanimously. > > > > The likely scenarios is if both 40g serial
or 4x10 CWDM > > cannot be built more cost-effectively than
4x individual > > 10ge, 40ge SMF will have very limited time
window, then > > people will escape it and jump straight to
100GE. > > > > My 1 cent. > > Frank > > > > -----Original Message----- > > From: > > [mailto:sjtrowbridge@xxxxxxxxxxxxxxxxxx]
> > Sent: Monday, August 04, 2008 8:50 AM > > To: > > Subject: Re: [802.3BA] Discussion on 40G for
="" 10 km SMF > > > > Hi Mori-san and others, > > It goes without saying that the cost of a
40G 4x10G CWDM > > transceiver will not over the long term fall
below 4x the > > cost of a 10G transceiver, but for a very
trivial reason: Any > > cost reduction that results from development
or volumes of40 > > GbE will also reduce the cost of a quad 10G
transceiver. So > > this is a meaningless comparison and not
helpful for the > > decision. The decision needs to be made
based on how the > > costs of 4x10G CWDM and serial 40G compare
to each other,not > > how they compare to the cost of 10G. 40G
serial technology > > has been in the market for ~6 years, and is
still stubbornly > > expensive. Costs are finally decreasing
somewhat, but the gap > > is not being closed vs. 10G because the cost
of 10G is > > decreasing even faster than the cost of 40G.
> > Regards, > > Steve > > > > -----Original Message----- > > From: Kazuyuki Mori [mailto:mori.kazuyuki-1@xxxxxxxxxxxxxx]
> > Sent: Sunday, August 03, 2008 10:21 PM > > To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx > > Subject: Re: [802.3BA] Discussion on 40G for
="" 10 km SMF > > > > TF members, > > > > I'm Kazuyuki Mori, Fujitsu Labs. I support
40G Serial and I > > basically agree with Takai-san regarding
below points. > > > > (1) Cost > > My understanding is
that, generally speaking, the final > > cost target for 40G optical transceiver
should be 2 -3 times > > of 10G transceivers. In order to achieve
this target , I > > again and again discussed the cost reduction
approaches with > > TOSA/ROSA suppliers, IC suppliers, optical
module suppliers > > and our laboratory experts. In case of CWDM,
I haven't found > > any technical solution to achieve this
target (<x4 cost of > > 10G transceiver), and there has been no
presentations in IEEE > > to show this cost reduction approaches until
now. On the > > other hand, 40G serial is feasible to
achieve this targetas > > shown in traverso_02_0708. > > I wonderthat 40G
transceiver cost will remain more than 4 > > times of 10G in future if once CWDM solution
is authorized. > > > > (2) Size > > I think the size
reduction is another big challenging > > target in CWDM as Chris already agreed in
recent dialogues. > > Some people say that monolithic DFB array
enables high > > density package solution, but CWDM option is
almost > > impossible to be realized because the same
active layerofLD > > cannot be applied. Also the hybrid
integration usingPLCwith > > an integrated AWG MUX is sometimes picked
up, but itisquite > > challenging due to high insertion loss of
AWG caused by > > intrinsic Gaussian profile, and also due to
AWG temperature > > dependence. In my perspective as a
researcher, optical > > integration approach in 40G CWDM has some
intrinsic problems > > and leads the cost increase. > > Pleaseremember that
this isn't the case of Vcsel array, > > but the case of DFBs and also with optical
mux. > > > > (3) Power > > Stevepointed out that
'40G SerDes are very power hungry', > > but this is not correct. Current SerDes is
for 16:1 and1:16, > > however 4:1 and 1:4 SerDes > > should be asuumed in We
need to compare using 4:1 and 1:4 > > SerDes. In our > > estimation, 2W is possible by deleting
unnecessary circuits > > from today's SerDes even when SiGe was used.
> > > > Kazuyuki Mori > > > > ----- Original Message ----- > > From: "Atsushi Takai"
<atsushi.takai@xxxxxxxxxx> > > To:
<STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx> > > Sent: Sunday, August 03, 2008 12:34 PM > > Subject: Re: [802.3BA] Discussion on 40G for
="" 10 km SMF > > > > > > > Jeff > > > > > > I do not know your background. > > > However I found, in your comment below,
you misunderstood > > the optical > > > transmission technologies. > > > I do not want to argue line by line. > > > > > > Just I would like to point one
sentence: > > > "The biggest downside of 40G
serial, seems to be the > > physics problem of > > > PMD.". > > > This is not true for 10km SMF. > > > The 40Gbit/s PMD was a technical
challenge in several years > > ago but now it > > > is not downside. > > > Even, we are discussing 1310-nm devices
while current > > module includes > > > 1550-nm devices. > > > (We can neglect dispersion issue in
case of 1310nm transmission) > > > > > > The biggest cost in current serial
module is silicon chip > > that is much > > > more > > > volume sensitive. > > > I hope you know the accumulative
shipment of 40Gbt/s client > > module is > > > around > > > 10K peaces or such range. > > > However IEEE confirmed market of 40GbE
10km serial enough for > > > standardization, you can expect much
lower cost with > higher volume. > > > > > > Also investment for 40Gbit/s transmission
networks started > > these years, > > > thus > > > industry started invest for 40Gbit/s
technologies. > > > You will find much activity in the
industry. > > > > > > All > > > > > > I am very concerning during the meeting
and e-mail discussion, > > > many of members may misunderstand the
40Gbit serial > > technology status and > > > activity in the industry, > > > and understand only the surface. > > > We, who has technology especially
optical device > > technology, should be > > > responsible to let people understand
the technology. > > > I will think about it. > > > > > > =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~= > > > Atsushi Takai > > > =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~= > > > ----- Original Message ----- > > > From: "Jeff Meyer"
<jmeyer@xxxxxxxxx> > > > To:
<STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx> > > > Sent: Sunday, August 03, 2008 2:33 AM > > > Subject: Re: [802.3BA] Discussion on
40G for ="" 10 kmSMF > > > > > > > > > Chris has a excellent point about > > > > > >
_Other Aspects_ > > > > > >
It is no longer possible to simplyincrease Baud to > > match data rate, > > >
because of fundamental electrical andoptical > propagation limits. > > >
This was recognized during the 100G SMF PMD discussion, > > with Serial > > >
never a viable alternative for the 10km or 40km reach. In the > > >
future, all data rates beyond 100G will use some form of > > multi-lane > > >
technology. 40G is the inflection point where cost and > > difficulty of > > >
Serial rises dramatically compared to multi-lane alternatives. > > >
Optical communication has reached the point that all > > other forms of > > >
communication (wired or wireless) reached many years ago, where > > >
simple modulation format serial solutions are not practical. > > > > > > > > > The biggest downside of 40G serial,
seems to be the physics > > problem of > > > PMD. However there are an increasing
number of long haul equipment > > > providers who have solved this problem.
There have been > > thousands of 40G > > > serial long haul installations deployed
to date. > > > > > > As far as the Cost, Power, Size &
Reliability I think this favors > > > serial. The cost saving of CWDM seems
largely drivenby the > > large number > > > of vendors providing 10G IC's and
components. But letus > > ponder, if the > > > 10GE fathers chose 4x 2.5G WDM to
reduce risk in thelate > > 1990's would > > > we be benefiting from the low costs and
the largenumber of > > vendors? All > > > we need is multiple vendors of 40G
serial componentsand > > the prices will > > > plummet. Lets face it the cost of SiGe
is not thatmuch > > higher than CMOS > > > unless you get to volumes greater than
100,000 parts.By > then, CMOS > > > processes will catch up to SiGe in FT.
I am amicrowave guy > > and the 40G > > > packaging is not difficult these days (
there are many > > vendors that can > > > do LTCC fine line packages and they are
"Open Tooled" so > > you can get a > > > reference design for the 40G electrical
packages for no > NRE ). If we > > > compare microwave packaging to flip
chip mounting of lasers > > and optics, > > > I would imagine optics costs more, but
I have no "hard > > data" to support > > > this. > > > > > > The biggest reason why I favor serial
over CWDM is the > > leadership for > > > the future. Lets take the risk like the
10G serial > > innovators did in the > > > late 90's. Once we get several
manufacturers of 40Gparts > > this prices > > > will plummet. > > > > > > Schedule Risk. Albeit the risk for
serial is higherbut how much? > > > > > > Let's keep technology moving forward
for the futuregenerations. > > > > > > > > > > > > Jeff Meyer > > > > > > > > > > > > > > > > > >> Takai-san痴
7/31/08 email discusses a number of points. Our > > arguments > > >> concerning his first two points
(Cost and Time to Market) are > > >> unchanged from cole_04_0708, so are
not repeated here. The > > remaining > > >> points are addressed below. > > >> > > >> _Power_ > > >> > > >> The long term power consumption of
40GE CWDM and 40GE Serial is > > >> similar. Four 10G un-cooled DFBs
and associated Laser Drivers use > > >> about the same power as one cooled
40G EML and > associated Modulator > > >> Driver. The remaining ICs are also
about the same if > > advanced process > > >> nodes and new designs are assumed.
As was pointed out by > > Joel Goergen > > >> during the Q&A session in > > >> comparable circuitry to 40GE CWDM
block diagram when drawn > > fairly to > > >> permit apples to apples comparison.
> > >> > > >> There is no basis for a claim at
this late stage in the > debate that > > >> Serial has a power advantage over
CWDM, and that CWDM > > 菟ower reduction > > >> plans are invisible.・In
jewell_03_0508, p.9 and again in > > >> traverso_02_0708 p. 12, ratios of
power between an > > aggressive Serial > > >> implementation and CWDM
implementation are 0.96 and 0.97, > > i.e. clear > > >> statements in pro-serial
presentations that there is no > advantage. > > >> > > >> _Size_ > > >> > > >> For future generation products,
CWDM has an advantage over > > Serial for > > >> fitting into a smaller form factor like
QSFP because similar to a > > >> 10GE-LR SFP+, the re-timing CDRs
can be moved outside of > > the module. > > >> Serial always has to have the 4:1
SerDes function in the > > module. Even > > >> with aggressive projections about
future component size > and power, > > >> Serial has a packaging and thermal
management design > > challenge to fit > > >> into QSFP. > > >> > > >> What is required to fit 40GE CWDM
into QSFP is optics > integration. > > >> This type of technology has been
described in numerous > > presentations > > >> to the HSSG and involves
flip-chipping lasers onto a PLC with an > > >> integrated AWG Mux. The CWDM grid
prevents use of a > monolithic DFB > > >> array and requires flip-chipping
discrete DFBs, but that > is a yield > > >> and cost issue not a feasibility or
size issue. The time > > line for such > > >> an advanced development program is
lengthy, but is similar to > > >> realistic PCB RF-interconnect 40GE
Serial development > > schedules. The > > >> investment required to bring this
advanced technology to > market is > > >> high, again similar to one required
for low cost 40GE Serial. > > >> > > >> In contrast, no advanced technology
development is > > required to quickly > > >> bring to market first generation
low cost CWDM products based on > > >> discrete optics packaged in a
larger form factor. > > >> > > >> _Reliability_ > > >> > > >> There is no current 1310nm 10G DFB
failure data that justifies > > >> bringing up concerns about the
reliability of a 4x10G > CWDM PMD. 10G > > >> 1310nm PMDs ship in volume today
with very high > > reliability. If there > > >> is actual field failure data behind
this concern,it would add > > >> credibility to have it presented. > > >> > > >> _Other Aspects_ > > >> > > >> It is no longer possible to simply
increase Baudto match > > data rate, > > >> because of fundamental electrical
and opticalpropagation > > limits. This > > >> was recognized during the 100G SMF
PMD discussion,with > > Serial never a > > >> viable alternative for the 10km or
40km reach. Inthe > > future, all data > > >> rates beyond 100G will use some
form of multi-lane > > technology. 40G is > > >> the inflection point where cost and
difficulty of Serial rises > > >> dramatically compared to multi-lane
alternatives. Optical > > >> communication has reached the point
that all other forms of > > >> communication (wired or wireless)
reached many years ago, > > where simple > > >> modulation format serial solutions
are not practical. > > >> > > >> Chris > > >> > > >> > > > > > > |