I understand that current 40G serial users
has been frustrated due to the cost.
My point was none convince me that 40G
CWDM will achieve less than 4 times cost of 10G.
I am afraid this means we will ignore the
DC application that is expected volume application that, as Mark mentioned,
is cost sensitive.
1310 nm is much easier than 1550nm. Noi
(3) Power consumption
Agein I am afraid that 40G CWDM will
achieve much less than 4 times of power consumption than 10G.
Opnext Japan, Inc
----- Original Message -----
Sent: Friday, August 01, 2008 4:37
Subject: RE: [802.3BA] Discussion
on 40G for ="" 10 km SMF
Hi Atsishi and others,
Let me comment on your points:
(1) COST - Today 40G serial technology is 70-100x the
cost of 10G technology, so even with the assumption that 4x10G CWDM is 6x the
cost of 10G, we still have that today's cost of serial 40G is >10x today's
cost of 4x10G. 40G technology costs have been coming down lately, but not
nearly as fast as the cost reduction of 10G. Matt has identified some
improvements that can help, but not enough to bring the technologies to cost
parity, and additional breakthroughs are needed before 40G serial could be
considered a cost advantage to 4x10G. If one looks at the historical cost
tends of 10G and 40G technology and asks when 40G will be cheaper than 4x10G,
the answer would be "never" since the cost reductions of 10G technology have
been so dramatic.
A lot of the cost will depend on volumes. If initial
costs are low, volumes will be high and the costs will reduce quickly. If
initial costs are high, as we expect for serial, volumes will be low and costs
will not drop as quickly. In fact, a major concern should be that with serial,
by the time the interfaces are cost effective enough to start selling in
volume, the market opportunity for 40G will have passed and the market will
have migrated to 100G (using 4xnG WDM, the parallel interface types that
serial advocates were hoping to avoid) and there will not be much interest to
go back and deploy 40G. Allesandro remarked that a choice would be to delete
the 40 GbE SMF objective, and while I don't want to do that either, I also
don't want to meet the objective in a way that is unlikely to receive wide
market adoption due to high cost.
(2) TIME - there is no question that both serial and CWDM
can be built if cost is not a factor. But if one simply wants to
build a 1310nm version of an OC-768 type interface, it will be way too
expensive for the Ethernet market and will not see significant adoption.
Significant work, including some (as yet unidentified) breakthroughs are
needed to make a 40G serial implementation that would be attractive in cost to
the Ethernet market.
(3) Power Consumption - Today, 40G SerDes are very power
hungry. It will take evolution in CMOS processes to make 40G Serial lower
power than 4x10G CWDM.
(4) Electrical Interface (I won't comment on the size) -
The electrical interface (host board to module) for 4x10G CWDM and Serial
would be exactly the same. There is no feasible 40G electrical signaling that
can be used for this, so the electrical interface is 4x10G in any case, which
could be used to drive the individual optical lanes for CWDM. For serial,
these 4 electrical lanes will need to be bit-multiplexed on the module
(functionally a 4:1 PMA).
(5) Risk for wavelength failure - I would love to see a
FIT analysis of this, looking at the probability of failures of the various
optical and electronic components of the interface. Chris has asserted that
the reliability of the optics is extremely high. Even if the optics are
serial, much of the electronics are parallel, and even the optics is logically
parallel since it consists of four bit-muxed VLs. There is no redundancy in
either case - if you lose any part of the optics, any electrical lane, lose
your lane marking logic, the interface is completely dead (you cannot
reconstruct a signal from 3 of 4 optical lanes - but neither can you
reconstruct a signal from a serial interface that has a stuck bit on a VL or
electrical lane in the host board to module interface). So what would be
interesting to know is if there is a significant difference in the total
interface reliability based on the choice of 4x10G CWDM or
(6) Speed breakthroughs - I don't think is correct that
we have seen regular speed breakthroughs. Things moved quickly up through
1GbE. 10GbE started out very high in cost, and volumes took far longer to ramp
than with previous generations. In transport networks, we were increasing
speed by a factor of four roughly every four years (OC-3/STM-1, OC-12/STM-4,
OC-48/STM-16, OC-192/STM-64, OC-768/STM-256). In both cases, we seem to see
slowing as we reach the limits of what can be done cost effectively in a
serial optical interface. 40G technology was introduced comercially in the
market 6-7 years ago, and adoption has yet to reach the pace of 10G technology
due to relatively higher cost. Nobody is discussing introduction of 160G
technology. Some of the breakthroughs to make 40G more cost effective involve
the use of advanced modulation formats to reduce the bit-rate, e.g., DP QPSK
encodes data on two phases of light per polarization at one quarter the
bit-rate. But this is effectively a four-lane parallel interface, the same as
we are trying to do for 40 GbE! For the Ethernet market, if one wants to do a
four-lane parallel interface, it is more reasonable to do this with simple NRZ
coding on parallel wavelengths instead of the type of sophisticated
transceiver one would use for amplified multi-wavelength systems going
thousands of km where you want to do sophisticated things to put all
of what are actually parallel lanes onto the same wavelength. As the
limits of a technology are reached, additional capacity is achieved with
parallel interfaces. Don't forget that the most successful interface
that 802.3 has ever developed (the 1 GbE copper interface) is a parallel
interface because it is not feasible to cost effectively transmit 1 Gb/s
serially over an electrical interface. Nobody thinks of this interface as
comprised of parallel lanes because it is just one RJ-45 connector at the end
of a cable. Nobody worries that individual lanes might fail because the
interface as a whole is quite reliable.
I may understand.
If you will find any violation below, please let me know.
I am supporting 40G serial.My view on 40G Serial and
CWDM is as below.
We can achieve less than 4x10G cost
using 40G serial
while we need some breakthrough
technology using 40G CWDM
I agree 40G CWDM will be 4-8
times of 10G as written in "cole_04_0708" page 8.
And most likely 6 times.
Using current technology, it is
difficult to achieve less than 4 because we have to pay for wavelength
In case of 40G serial, module
structure is the same as X2.
I believe we can achieve less
than 4 times cost for each part in the 40G module comparing 10G
are waiting 3rd generation SERDES and 2nd generation of driver and TIA IC to
achieve low cost 40GbE serial.
I am sure that industry is working on
There exists plural 40G serial
module vendors today using 1550-nm EA-DFB.
1310-nm EA-DFB is easier because
we can neglect dispersion problem.
Thus 40GbE serial is
And cost reduction plan is
I also sure 40G CWDM will be
available if market will accept larger than 4 times cost.
Cost reduction plan will follow the
same as 10G and plan for less than 4 times is invisible today.
(3) Power consumption
We need also breakthrough to achieve
less than 4 time power consumption using CWDM.
Power consumption reduction plan is
We are sure we can achieve less than 4
time power consumption using serial in future.
I am not sure it is too early to talk
40G electrical interface.
But 40GbE serial has possibility
for XFP or SFP+ size.
I did not hear LX4 XFPor SFP+ due
to pin constraint and power consumption.
(5) Risk for
WDM technology has always the risk for
wavelength failure, while serial does not have.
We may resolve some way for
40G CWDM because of high reliability of long wavelength optical
(6) Another aspect
We made speed breakthrough every 4 or
5 years in the past.
We started to deliver 10G modules in 1997.
The 300-pin MSA started in
10GbE was issued in 2002.
40G is the next milestone for
technology evolution and now is a little bit behind the past
(We had unhappy period that every
progress seemed to stop.)
Today 40G is the technology to
challenge and overcome for both optical and electrical
I think IEEE should not avoid
such technology evolution.
I believe IEEE should take 40GbE serial.
Division, Opnext Japan, Inc
----- Original Message -----
Sent: Wednesday, July 30, 2008
Subject: RE: [802.3BA]
Discussion on 40G for ="" 10 km SMF
First, let me say
that the email below is intended to make sure that this group does not
stray in a direction that would ultimately lead to the violation of
IEEE-SA Antitrust and Competition Policy. As chair, I am remaining
neutral on the TF?s technical decisions.
Regardless of the
decision that this body makes, the market may demand that both solutions
are developed anyway.
Please note in
the following document from the IEEE, ?Promoting Competition and
You Need to Know about the IEEE Standards Association?s Antitrust and
Competition Policy,? which may be
found at http://standards.ieee.org/resources/antitrust-guidelines.pdf.
Please note the following
example, selecting one technology for inclusion in a standard is lawful,
but an agreement to prohibit standards
participants (or implementers)
from implementing a competing standard or rival technology would be
unlawful ? although as a practical matter, a successful standard may
lawfully achieve this result through the workings of the
As I have phrased it to the
Task Force, the Task Force makes decisions about what it is going to do,
it does not make decisions about what it is not going to
Regardless of the decision
that this Task Force makes, it is very easy to envision both
implementations getting developed in the industry. Given the need
stated by CWDM supporters for a near term solution, it is easy to envision
an industry effort happening if the TF goes serial. It is just as
easy to envision a new CFI happening for a serial solution if the TF
chooses to go CWDM.
Also, as a point of
clarification, as I am currently looking at the presentation for another
discussion, you may wish to refer to Flatman_01_0108 (http://grouper.ieee.org/groups/802/3/ba/public/jan08/flatman_01_0108.pdf),
which is a survey of data centers that Alan Flatman did that shows 40G
being deployed in access-to-distribution links in 2010.
Atsushi Takai [mailto:atsushi.takai@xxxxxxxxxx]
Sent: Wednesday, July 30, 2008 2:26
Subject: Re: [802.3BA] Discussion on
40G for ="" 10 km SMF
I agree that DC
application is cost sensitive.
As many people agreed
in some presentations at meeting, CWDM will be cheaper at near term and
serial will became cheaper in maybe 2011 or
transceiver supplier have to develop CWDM in 2009 timeframe and serial in
2010 or 11.
This development will
cost much. And I do not think CWDM cost in 2009 or 2010 will be cheaper
Even more DC
application users can choose 8x10G CWDM that has more
I do not think CWDM
has superior merit for DC application.
Also I think there
was a presentation that said that DC will start install 40G in 2015 or
Marketing Division, Opnext Japan,
Sent: Wednesday, July
30, 2008 4:08 AM
Subject: Re: [802.3BA]
Discussion on 40G for ="" 10 km SMF
I agree some reflector
discussion would be helpful on this topic.
I characterize the
discussion I heard around the choice of PMD as really boiling down to a
debate on the primary applications and the drivers for those
The original justification
for adding the 40G SMF objective was primarily based on the application
links. There was also other applications such as for use in
interconnecting to OTN equipment which is good for BMP. In both
cases lower cost solutions are preferential. The debate appears to
revolve around what other assumptions there are around market timing,
technology risks, cost projections and operational issues
To me the simple view is
that to achieve low cost, you need higher volume. Higher volume is
achieved by the having a solution that addresses the largest primary
application and as many others as possible. I am assuming that the
primary application is still the DC.
Since DC applications are
inherently much more sensitive to cost, a near term low cost solution is
needed or else the application will likely not be adopted. In this
case, if 40G SMF PMD is uneconomical in the near term then the DC users
will likely stay with nx10G as long as possible and then presumably
assess the 40G/100G economics at some later
The argument for adopting
serial technology now is that the potential higher volume of the DC
application will trigger the necessary development investments now and
drive the cost of that technology down so we will ultimately get it to
the low cost solutions needed. My concern is that the timing and
cost windows needed for the DC application do no fit with that model and
we would end up with little adoption in that market and end up with a
lower volume, higher cost PMD which is what we would all like to
John DAmbrosia [mailto:jdambrosia@xxxxxxxxxxxxxxx]
Sent: Monday, July 28, 2008 6:53
Subject: [802.3BA] Discussion on
40G for ="" 10 km SMF
Dear Task Force
Per Motion #9 from July,
the editorial team is working on creating a ?a draft based on adopted baseline proposals for
circulation prior to the September 2008 interim
Unfortunately, at the July meeting the
Task Force did not reach consensus on a baseline proposal to satisfy
the 40G over => 10km SMF objective. Therefore, in September we need to
reach closure on this issue.
said, I would like to strongly recommend that the TF make use of the
reflector to discuss the various issues of debate that have been going
on, both during the meetings and during offline discussions.
the next several weeks to have meaningful debate so we can reach
consensus at the September meeting.