Re: [802.3_100GNGOPTX] Emerging new reach space
Chris,
No, I have not said that.
What I said is that parallel SMF AOC
(in the 10 Gb/s space) is competitive to copper and MMF solutions. I view
the challenge for the SMF parallel the same as for MMF: to scale the speed.
Therefore, the cost ratio between the parallel SMF and parallel MMF would
likely remain the same (excluding the cable cost).
On the other side, we have today 10km
WDM (4x10 Gb/s) that in my mind is significantly more expensive than MMF
(just comparing the transceivers) - please correct me if I am wrong. Maybe
you can provide the relative cost of the SMF WDM 10km to MMF 100m?
The WDM solution will, in my mind, have
to achieve significant cost reductions to compete with these other solutions.
I agree with you that at one point the
WDM will be more cost effective. We will have to judge the evidence to
decide what that distance is.
Regards,
Peter
Petar Pepeljugoski
IBM Research
P.O.Box 218 (mail)
1101 Kitchawan Road, Rte. 134 (shipping)
Yorktown Heights, NY 10598
e-mail: petarp@xxxxxxxxxx
phone: (914)-945-3761
fax: (914)-945-4134
From:
"Chris Cole"
<chris.cole@xxxxxxxxxxx>
To:
Petar Pepeljugoski/Watson/IBM@IBMUS,
<STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx>
Date:
11/18/2011 04:36 PM
Subject:
RE: [802.3_100GNGOPTX]
Emerging new reach space
Petar
You are simply stating what
the requirement is for the 1000m application; it has to be comparable to
MMF optics cost. If you are also stating there have been proposals for
solution that cost less than 100GE-LR4, again, no one would disagree.
However, there have been
no proposals for 1000m duplex SMF solutions, so where do you see the comparison?
Chris
From: Petar Pepeljugoski [mailto:petarp@xxxxxxxxxx]
Sent: Friday, November 18, 2011 1:26 PM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
Chris,
I am sorry to disagree with you. There were at least two presentations
that argued about parallel SMF, one of which provided estimates of such
parallel module. Unless I misunderstood, during the discussion it was asserted
(I don't know if this is really true) that the cable cost with 4 fibers
would be approximately the same cost as one fiber (I guess where this is
coming from: when you take into account the cost of jacketing and laying
the fiber).
The existence of short SMF based parallel active cables on the market (at
least one company sells 4channel wide AOC) speaks for itself: the cost
is competitive enough to other solutions (be it active MMF or copper) and
people buy them.
Now, I have to admit I have no idea how much the WDM based solution would
cost, but based on the 4 channel wide SMF AOCs I can make a pretty good
estimate for the cost of 500m or 1km link, since the fiber adds 0.5 dB/km
only and it can easily be absorbed.
Maybe on the issue of relative cable cost (four vs. one fiber) someone
from the fiber manufacturers/cabling companies can help here.
Regards,
Peter
Petar Pepeljugoski
IBM Research
P.O.Box 218 (mail)
1101 Kitchawan Road, Rte. 134 (shipping)
Yorktown Heights, NY 10598
e-mail: petarp@xxxxxxxxxx
phone: (914)-945-3761
fax: (914)-945-4134
From: Chris
Cole <chris.cole@xxxxxxxxxxx>
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Date: 11/18/2011
03:25 PM
Subject: Re:
[802.3_100GNGOPTX] Emerging new reach space
Paul
A number of good comments, but I am afraid you overreached with your assertion
that it is likely that parallel SMF will offer the lowest cost. Nothing
of the sort has been demonstrated in NG 100G SG.
Further, there are a number participants like me for whom it is self evident
that parallel SMF is a more expensive approach than WDM duplex SMF. So
far, we have not put in the time to rigorously show why this is the case,
mainly because of a shared perception with Jack that parallel SMF is a
non-starter for large IDCs. However, if it turns out that this is not a
real barrier, then we will need to step up to the plate and duke it out
with cost numbers.
Chris
From: Kolesar, Paul [mailto:PKOLESAR@xxxxxxxxxxxxx]
Sent: Friday, November 18, 2011 12:08 PM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
Jack,
Thanks for your view points. While your assessment of the big systems
users may be accurate, I am not aware of any going on record in favor or
against any particular new proposal yet. They may be more like me.
I still do not have enough information to determine a solid preference.
But as you have expressed, at this point I too think it is likely
that parallel singe-mode will offer the lowest cost, especially when weighted
by the channel length distributions. We will see if that is true
and whether that is sufficient to be persuasive to the group to go in that
direction.
Also we must remember that while the big system users take center stage
in our views of the world because they participate in our discussions and
are potential early and substantial adopters, for every one of them there
are hundreds of other system users who are not represented. And it
is very hard for them to be heard, not just logistically, but with sufficient
sincerity to affect the standard. A case in point: using a survey,
Corning collected the views of 20 such users during the 802.3ba development.
See http://www.ieee802.org/3/ba/public/AdHoc/MMF-Reach/swanson_xr_01_0608.pdf
Although we spent many meetings and teleconferences trying to address their
guidance, none was implemented.
In some ways our current activity in search of a lower-cost alternative
to the existing standard to support data center channels longer than 150
m can be viewed as the consequence of that inability. Because we
have now moved up to 25G lane rates we are focusing on SM solutions to
fill that void. Yet the optimal SM technologies to do this job are
still potentially out on or beyond the horizon. If we had implemented
longer reach on MMF for both 40G and 100G as those surveyed customers indicated,
our current activities might have been delayed until a more mature future
because the implementation cost of their directives would not have posed
such a formidable market acceptance barrier, and therefore I suspect one
more tolerant to awaiting replacement alternatives.
I’m hoping we can do it better this time. That’s why I am working
to provide the assessment tools we need, and to open the discussions around
cost and existing price.
I also agree with Chris regarding the reach objective. The existing proposals
need to bake more, and we may hear even more varied proposals next meeting.
Regards,
Paul
-----Original Message-----
From: Chris Cole [mailto:chris.cole@xxxxxxxxxxx]
Sent: Friday, November 18, 2011 1:12 PM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
Jack,
Thank you for continuing to lead the discussion. I am hoping it encourages
others to jump in with their perspectives, otherwise you will be stuck
architecting the new standard by yourself with the rest of us sitting back
and observing.
Your email is also a good prompt to start discussing the specific reach
objective for 100GE-nR4. Since you mention 2000m reach multiple times in
your email, can you give a single example of a 2000m Ethernet IDC link?
I am aware of many 150m to 600m links, with 800m mentioned as long term
future proofing, so rounding up to 1000m is already conservative. I understand
why several IDC operators have asked for 2km; it was the next closest existing
standard reach above their 500m/600m need; see for example page 10 of Donn
Lee's March 2007 presentation to the HSSG (http://www.ieee802.org/3/hssg/public/mar07/lee_01_0307.pdf).
It is very clear what the need is, and why 2km is being brought up.
Another example of IDC needs is in a 10x10G MSA white paper (http://www.10x10msa.org/documents/10X10%20White%20Paper%20final.pdf),
where Bikash Koley and Vijay Vusirikala of Google show that their largest
data center requirements are met by a <500m reach interface.
In investigating the technology for 100GE-nR4, we may find as Pete Anslow
has pointed out in NG 100G SG, that the incremental cost for going from
1000m to 2000m is negligible. We may then chose to increase the standardized
reach. However to conclude today that this is in fact where the technology
will end up is premature. We should state the reach objective to reflect
the need, not our speculation about the capabilities of yet to be defined
technology.
Thank you
Chris
-----Original Message-----
From: Jack Jewell [mailto:jack@xxxxxxxxxxxxxx]
Sent: Friday, November 18, 2011 9:38 AM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
Hello All,
Thanks for all the contributions to this discussion. Here's a synopsis
and
my current take on where it's heading (all in the context of 150-2000m
links).
Starting Point: Need for significantly-lower cost/power links over
150-2000m reaches has been expressed for several years. Last week in
Atlanta, four technical presentations on the subject all dealt with
parallel SMF media. Straw polls of "like to hear more about ___"
received
41, 48, 55, and 48 votes, the 41 for one additionally involving new fiber.
The poll "to encourage more on…duplex SMF PMDs" received 35
votes. Another
straw poll gave strong support for the most-aggressive low-cost target.
Impressions from discussion and Atlanta meeting: Systems users (especially
the largest ones) are strongly resistant to adopting parallel SMF. (not
addressing reasons for that position, just stating an observation.) LR4
platform can be extended over duplex SMF via WDM by at least one more
"factor-4" generation, and probably another (DWDM for latter);
PAM and
line-rate increase may extend duplex-SMF's lifetime yet another
generation.
My Current Take: Given a 2-or-3-generation (factor-4; beyond 100GNGOPTX)
longevity of duplex SMF, I'm finding it harder to make a compelling case
for systems vendors to adopt parallel SMF for 100GNGOPTX. My current
expectation is that duplex SMF will be the interconnection medium. My
ongoing efforts will have more duplex-SMF content. I still think parallel
SMF should deliver lowest cost/power for 100GNGOPTX, and provide an
additional 1-2 generations of longevity; just don't see system vendors
ready to adopt it now.
BUT: What about the Starting Point (above), and the need for
significantly-lower cost/power?? If a compelling case is to be made for
an
alternative to duplex SMF, it will require a very crisp and convincing
argument for significantly-lower cost/power than LR4 ("fair"
comparison
such as mentioned earlier), or other duplex SMF approaches. Perhaps a
modified version of LR4 can be developed with lower-cost/power lasers that
doesn't reach 10km. If, for whatever reasons, systems vendors insist on
duplex SMF, but truly need significantly-lower cost/power, it may require
some compromise, e.g. "wavelength-shifted" SMF, or something
else. Would
Si Photonics really satisfy the needs with no compromise? Without saying
they won't, it seems people aren't convinced, because we're having these
discussions.
Cheers, Jack
On 11/17/11 10:23 AM, "Arlon Martin" <amartin@xxxxxxxxxx>
wrote:
>Hello Jack,
>To your first question, yes, we are very comfortable with LAN WDM
>spacing. That never was a challenge for the technology. We have chosen
to
>perfect reflector gratings because of the combination of small size
and
>great performance. I am not sure exactly what you are asking in your
>second question. There may be a slightly lower loss to AWGs than
>reflector gratings. That difference has decreased as we have gained
more
>experience with gratings. For many applications like LR and mR, the
much,
>much smaller size (cost is related to size) of reflector gratings makes
>them the best choice.
>
>Thanks, Arlon
>
>-----Original Message-----
>From: Jack Jewell [mailto:jack@xxxxxxxxxxxxxx]
>Sent: Thursday, November 17, 2011 6:42 AM
>To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
>Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
>
>Hi Arlon,
>Thanks very much for this. You are right; I was referring to thin film
>filters. My gut still tells me that greater tolerances should accompany
>wider wavelength spacing. So I'm guessing that your manufacturing
>tolerances are already "comfortable" at the LAN WDM spacing,
and thus the
>difference is negligible to you. Is that a fair statement? Same could
be
>true for thin film filters. At any rate, LAN WDM appears to have one
>factor-4 generation advantage over CWDM in this discussion, and it's
good
>to hear of its cost effectiveness. Which brings up the next question.
Your
>data on slide 15 of Chris's presentation referenced in his message
shows
>lower insertion loss for your array waveguide (AWG) DWDM filter than
for
>the grating filters. Another factor-of-4 data throughput may be gained
in
>the future via DWDM.
>Cheers, Jack
>
>On 11/16/11 10:51 PM, "Arlon Martin" <amartin@xxxxxxxxxx>
wrote:
>
>>Hello Jack,
>>As a maker of both LAN WDM and CWDM filters, I would like to comment
on
>>the filter discussion. WDM filters can be thin film filters (to
which you
>>may be referring) but more likely, they are PIC-based AWGs or PIC-based
>>reflector gratings. In our experience at Kotura with reflector
gratings
>>made in silicon, both CWDM and LAN WDM filters work equally well
and are
>>roughly the same size. It is practical to put 40 or more wavelengths
on a
>>single chip. We have done so for other applications. There is plenty
of
>>headroom for more channels when the need arises for 400 Gb/s or
1 Tbs.
>>There may be other reasons to select CWDM over LAN WDM, but, in
our
>>experience, filters do not favor one choice over the other.
>>
>>Arlon Martin, Kotura
>>
>>-----Original Message-----
>>From: Jack Jewell [mailto:jack@xxxxxxxxxxxxxx]
>>Sent: Wednesday, November 16, 2011 9:09 PM
>>To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
>>Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
>>
>>Thanks Chris for your additions.
>>1. "CWDM leads to simpler optical filters versus "closer"
WDM (LAN WDM)"
>>-
>>For a given throughput transmission and suppression of
>>adjacent-wavelength
>>signals (assuming use of same available optical filter materials),
use of
>>a wider wavelength spacing can be accomplished with wider thickness
>>tolerance and usually with fewer layers. The wider thickness tolerance
is
>>basic physics, with which I won't argue. In this context, I consider
>>"wider thickness tolerance" as "simpler."
>>2. "CWDM leads to lower cost versus "closer" WDM
because cooling is
>>eliminated" - I stated no such thing, though it's a common
perception.
>>Ali
>>Ghiasi suggested CWDM (implied by basing implementation on 40GBASE-LR4)
>>might be lower cost, without citing the cooling issue. Cost is
a far more
>>complex issue than filter simplicity. You made excellent points
regarding
>>costs in your presentation cited for point 1, and I cited LAN WDM
>>(100GBASE-LR4) advantages as "better-suited-for-integration,
and
>>"clipping
>>off" the highest-temp performance requirement." We must
recognize that at
>>1km vs 10km, chirp issues are considerably reduced.
>>3. "CWDM is lower power than "closer" WDM power"
- I stated no such
>>thing,
>>though it's a common perception. I did say "More wavelengths
per fiber
>>means more power per channel," which is an entirely different
statement,
>>and it's darned hard to argue against the physics of it (assuming
same
>>technological toolkit).
>>All I stated in the previous message are the advantages of CWDM
(adopted
>>by 40GBASE-LR4) and LAN WDM (adopted by 100GBASE-LR4), without
favoring
>>one over the other for 100GbE (remember we're talking ~1km, not
10km).
>>But
>>my forward-looking (crude) analysis of 400GbE and 1.6TbE clearly
favors
>>LAN WDM over CWDM - e.g. "CWDM does not look attractive on
duplex SMF
>>beyond 100GbE," whereas the wavelength range for 400GbE LAN
16WDM over
>>duplex SMF "is realistic." Quasi-technically speaking
Chris, we're on the
>>same wavelength (pun obviously intended) :-)
>>Paul Kolesar stated the jist succinctly: "that parallel fiber
>>technologies
>>appear inevitable at some point in the evolution of single-mode
>>solutions.
>> So the question becomes a matter of when it is best to embrace
them." [I
>>would replace "inevitable" with "desirable."]
From a module standpoint,
>>it's easier, cheaper, lower-power to produce a x-parallel solution
than a
>>x-WDM one (x is number of channels), and it's no surprise that
last
>>week's
>>technical presentations (by 3 module vendors and 1 independent)
had a
>>parallel-SMF commonality for 100GNGOPTX. There is a valid argument
for
>>initial parallel SMF implementation, to be later supplanted by
WDM,
>>particularly LAN WDM. With no fiber re-installations.
>>To very recent messages, we can choose which pain to feel first,
parallel
>>fiber or PAM, but by 10TbE we're likely get both - in your face
or
>>innuendo :-)
>>Jack
>>
>>
>>
>>On 11/16/11 6:53 PM, "Chris Cole" <chris.cole@xxxxxxxxxxx>
wrote:
>>
>>>Hello Jack,
>>>
>>>You really are on a roll; lots of insightful perspectives.
>>>
>>>Let me clarify a few of items so that they don't detract from
your
>>>broader ideas.
>>>
>>>1. CWDM leads to simpler optical filters versus "closer"
WDM (LAN WDM)
>>>
>>>This claim may have had some validity in the past, however
it has not
>>>been the case for many years. This claim received a lot of
attention in
>>>802.3ba TF during the 100GE-LR4 grid debate. An example presentation
is
>>>http://www.ieee802.org/3/ba/public/mar08/cole_02_0308.pdf,
where on
>>>pages
>>>13, 14, 15, and 16 multiple companies showed there is no practical
>>>implementation difference between 20nm and 4.5nm spaced filters.
>>>Further,
>>>this has now been confirmed in practice with 4.5nm spaced LAN
WDM
>>>100GE-LR4 filters in TFF and Si technologies manufactured with
no
>>>significant cost difference versus 20nm spaced CWDM 40GE-LR4
filters.
>>>
>>>If there is specific technical information to the contrary,
it would be
>>>helpful to see it as a presentation in NG 100G SG.
>>>
>>>2. CWDM leads to lower cost versus "closer" WDM because
cooling is
>>>eliminated
>>>
>>>This claim has some validity at lower rates like 1G or 2.5G,
but is not
>>>the case at 100G. This has been discussed at multiple 802.3
optical
>>>track
>>>meetings, including as recently as the last NG 100G SG meeting.
We again
>>>agreed that the cost of cooling is a fraction of a percent
of the total
>>>module cost. Even for a 40GE-LR4 module, the cost of cooling,
if it had
>>>to be added for some reason, would be insignificant. Page 4
of the above
>>>cole_02_0308 presentation discusses why that is.
>>>
>>>This claim to some extent defocuses from half a dozen other
cost
>>>contributors which are far more significant. Those should be
at the top
>>>of the list instead of cooling. Further, if cooling happens
to enable a
>>>technology which reduces by a lot a significant cost contributor,
then
>>>it
>>>becomes a big plus instead of an insignificant minus.
>>>
>>>If there is specific technical information to the contrary,
a NG 100G SG
>>>presentation would be a great way to introduce it.
>>>
>>>3. CWDM is lower power than "closer" WDM power.
>>>
>>>The real difference between CWDM and LAN DWDM is that un-cooled
is lower
>>>power. However how much lower strongly depends on the specific
transmit
>>>optics and operating conditions. In 100G module context it
can be 10% to
>>>30%. However, for some situations it could be a lot more savings,
and
>>>for
>>>others even less. No general quantification of the total power
savings
>>>can be made; it has to be done on a case by case basis.
>>>
>>>Chris
>>>
>>>-----Original Message-----
>>>From: Jack Jewell [mailto:jack@xxxxxxxxxxxxxx]
>>>Sent: Wednesday, November 16, 2011 3:20 PM
>>>To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
>>>Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
>>>
>>>Great inputs! :-)
>>>Yes, 40GBASE-LR4 is the first alternative to 100GBASE-LR4 that
comes to
>>>mind for duplex SMF. Which begs the question: why are they
different?? I
>>>can see advantages to either: (40G CWDM vs 100G closerWDM)
- uncooled,
>>>simple optical filters vs better-suited-for-integration, and
"clipping"
>>>off" the highest-temp performance requirement.
>>>It's constructive to look forward, and try to avoid unpleasant
surprises
>>>of "future-proof" assumptions (think 802.3z and FDDI
fiber - glad I
>>>wasn't
>>>there!). No one likes "forklift upgrades" except
maybe forklift
>>>operators,
>>>who aren't well-represented here. Data centers are being built,
so
>>>here's
>>>a chance to avoid short-sighted mistakes. How do we want 100GbE,
400GbE
>>>and 1.6TbE to look (rough guesses at the next generations)?
Here are 3
>>>basic likely scenarios, assuming (hate to, but must) 25G electrical
>>>interface and no electrical mux/demux. Considering duplex SMF,
>>>4+4parallel
>>>SMF, and 16+16parallel SMF:
>>>Generation
>>>100GbE duplex-SMF / 4WDM
4+4parallel / no WDM
>>>16+16parallel / dark fibers
>>>400GbE duplex-SMF / 16WDM
4+4parallel / 4WDM
>>>16+16parallel / no WDM
>>>1.6TbE duplex-SMF / 64WDM
4+4parallel / 16WDM
>>>16+16parallel / 4WDM
>>>The above is independent of distances in the 300+ meter range
we're
>>>considering. Yes, there are possibilities of PAM encoding and
electrical
>>>interface speed increases. Historically we've avoided the former,
and
>>>the
>>>latter is expected to bring a factor of 2, at most, for these
>>>generations.
>>>Together, they might bring us forward 1 factor-of-4 generation
further.
>>>For 40GbE or 100GbE, 20nm-spaced CWDM is nice for 4WDM (4 wavelengths).
>>>At
>>>400GbE, 16WDM CWDM is a 1270-1590nm stretch, with 16 laser
products
>>>(ouch!). 20nm spacing is out of the question for 64WDM (1.6TbE).
CWDM
>>>does
>>>not look attractive on duplex SMF beyond 100GbE.
>>>OTOH, a 100GBASE-LR4 - based evolution on duplex SMF, with
~4.5nm
>>>spacing,
>>>is present at 100GbE. For 400GbE, it could include the same
4
>>>wavelengths,
>>>plus 4-below and 12-above - a 1277.5-1349.5nm wavelength span,
which is
>>>realistic. The number of "laser products" is fuzzy,
as the same
>>>epitaxial
>>>structure and process (except grating spacing) may be used
for maybe a
>>>few, but nowhere near all, of the wavelengths. For 1.6TbE 64WDM,
LR4's
>>>4.5nm spacing implies a 288nm wavelength span and a plethora
of "laser
>>>products." Unattractive.
>>>On a "4X / generational speed increase," 4+4parallel
SMF gains one
>>>generation over duplex SMF and 16+16parallel SMF gains 2 generations
>>>over
>>>duplex SMF. Other implementations, e.g. channel rate increase
and/or
>>>encoding, may provide another generation or two of "future
>>>accommodation."
>>>The larger the number of wavelengths that are multiplexed,
the higher
>>>the
>>>loss budget that must be applied to the laser-to-detector (TPlaser
to
>>>TPdetector) link budget. More wavelengths per fiber means more
power per
>>>channel, i.e. more power/Gbps and larger faceplate area. While
duplex
>>>SMF
>>>looks attractive to systems implementations, it entails significant(!!)
>>>cost implications to laser/transceiver vendors, who may not
be able to
>>>bear "cost assumptions," and additional power requirements,
which may
>>>not
>>>be tolerable for systems vendors.
>>>I don't claim to "have the answer," rather attempt
to frame the question
>>>pointedly "How do we want to architect the next few generations
of
>>>Structured Data Center interconnects?" Insistence on duplex
SMF works
>>>for
>>>this-and-maybe-next-generation, then may hit a wall. Installation
of
>>>parallel SMF provides a 1-or-2-generation-gap of "proofing,"
with higher
>>>initial cost, but with lower power throughout, and pushing
back the need
>>>for those abominable "forklift upgrades."
>>>Jack
>>>
>>>
>>>On 11/16/11 1:00 PM, "Kolesar, Paul" <PKOLESAR@xxxxxxxxxxxxx>
wrote:
>>>
>>>>Brad,
>>>>The fiber type mix in one of my contributions in September
is all based
>>>>on cabling that is pre-terminated with MPO(MTP)array connectors.
>>>>Recall
>>>>that single-mode fiber represents about 10 to 15% of those
channels.
>>>>Such cabling infrastructure provides the ability to support
either
>>>>multiple 2-fiber or parallel applications by applying or
removing
>>>>fan-outs from the ends of the cables at the patch panels.
The fan-outs
>>>>transition the MPO terminated cables to collections of
LC or SC
>>>>connectors. If fan-outs are not present, the cabling
is ready to
>>>>support
>>>>parallel applications by using array equipment cords. As
far as I am
>>>>aware this pre-terminated cabling approach is the primary
way data
>>>>centers are built today, and has been in practice for many
years. So
>>>>array terminations are commonly used on single-mode cabling
>>>>infrastructures. While that last statement is true,
it could leave a
>>>>distorted impression if I also did not say that virtually
the entire
>>>>existing infrastructure e!
>>>> mploys fan-outs today simply because parallel applications
have not
>>>>been
>>>>deployed in significant numbers. But migration to
parallel optic
>>>>interfaces is a matter of removing the existing fan-outs.
This is what
>>>>I
>>>>tried to describe at the microphone during November's meeting.
>>>>
>>>>Regards,
>>>>Paul
>>>>
>>>>-----Original Message-----
>>>>From: Brad Booth [mailto:Brad_Booth@xxxxxxxx]
>>>>Sent: Wednesday, November 16, 2011 11:34 AM
>>>>To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
>>>>Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
>>>>
>>>>Anyone have any data on distribution of parallel vs duplex
volume for
>>>>OM3/4 and OS1?
>>>>
>>>>Is most SMF is duplex (or simplex) given the alignment
requirements?
>>>>
>>>>It would be nice to have a MMF version of 100G that doesn't
require
>>>>parallel fibers, but we'd need to understand relative cost
differences.
>>>>
>>>>Thanks,
>>>>Brad
>>>>
>>>>
>>>>
>>>>-----Original Message-----
>>>>From: Ali Ghiasi [aghiasi@xxxxxxxxxxxx<mailto:aghiasi@xxxxxxxxxxxx>]
>>>>Sent: Wednesday, November 16, 2011 11:04 AM Central Standard
Time
>>>>To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
>>>>Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
>>>>
>>>>Jack
>>>>
>>>>If there is another LR4 PMD out there the best starting
point would be
>>>>40Gbase-LR4, look at its cost structure, and build a 40G/100G
>>>>compatible
>>>>PMD.
>>>>
>>>>We also need to understand the cost difference between
parallel MR4 vs
>>>>40Gbase-LR4 (CWDM). The 40Gbase-LR4 cost with time
could be assumed
>>>>identical to the new 100G MR4 PMD. Having this baseline
cost then we
>>>>can
>>>>compare its cost with 100GBase-LR4 and parallel MR4. The
next step is
>>>>to
>>>>take
>>>>into account higher cable and connector cost associated
with parallel
>>>>implementation then identify at what reach it gets to parity
with 100G
>>>>(CWDM) or
>>>>100G (LAN-WDM).
>>>>
>>>>In the mean time we need to get more direct feedback from
end users if
>>>>the parallel SMF is even an acceptable solution for reaches
of 500-1000
>>>>m.
>>>>
>>>>Thanks,
>>>>Ali
>>>>
>>>>
>>>>
>>>>On Nov 15, 2011, at 8:41 PM, Jack Jewell wrote:
>>>>
>>>>Thanks for this input Chris.
>>>> I'm not "proposing" anything here, rather trying
to frame the
>>>>challenge,
>>>>so that we become better aligned in how cost-aggressive
we should be,
>>>>which guides the technical approach. As for names, "whatever
works" :-)
>>>>It would be nice to have a (whatever)R4, be it nR4 or something
else,
>>>>and
>>>>an english name to go with it. The Structured Data Center
(SDC) links
>>>>you
>>>>describe in your Nov2011 presentation are what I am referencing,
except
>>>>for the restriction to "duplex SMF." My input
is based on use of any
>>>>interconnection medium that provides the overall lowest-cost,
>>>>lowest-power solution, including e.g. parallel SMF.
>>>>Cost comparisons are necessary, but I agree tend to be
dicey. Present
>>>>10GbE costs are much better defined than projected 100GbE
NextGen
>>>>costs,
>>>>but there's no getting around having to estimate NextGen
costs, and
>>>>specifying the comparison. Before the straw poll, I got
explicit
>>>>clarification that "LR4" did NOT include mux/demux
IC's, and therefore
>>>>did not refer to what is built today. My assumption was
a "fair" cost
>>>>comparison between LR4 and (let's call it)nR4 - at similar
stage of
>>>>development and market maturity. A relevant stage is during
delivery of
>>>>high volumes (prototype costs are of low relevance). This
does NOT
>>>>imply
>>>>same volumes. It wouldn't be fair to project ER costs based
on SR or
>>>>copper volumes. I'm guessing these assumptions are mainstream
in this
>>>>group. That would make the 25% cost target very aggressive,
and a 50%
>>>>cost target probably sufficient to justify an optimized
solution. Power
>>>>requirements are a part of the total cost of ownership,
and should be
>>>>consider!
>>>> ed, but perhaps weren't.
>>>>The kernel of this discussion is whether to pursue "optimized
>>>>solutions"
>>>>vs "restricted solutions." LR4 was specified
through great scrutiny and
>>>>is expected to be a very successful solution for 10km reach
over duplex
>>>>SMF. Interoperability with LR4 is obviously desirable,
but would a
>>>>1km-spec'd-down version of LR4 provide sufficient cost/power
savings
>>>>over
>>>>LR4 to justify a new PMD and product development? Is there
another
>>>>duplex
>>>>SMF solution that would provide sufficient cost/power savings
over LR4
>>>>to
>>>>justify a new PMD and product development? If so, why wouldn't
it be
>>>>essentially a 1km-spec'd-down version of LR4? There is
wide perception
>>>>that SDC's will require costs/powers much lower than are
expected from
>>>>LR4, so much lower that it's solution is a major topic
in HSSG. So far,
>>>>it looks to me like an optimized solution is probably warranted.
But
>>>>I'm
>>>>not yet convinced of that, and don't see consensus on the
issue in the
>>>>group, hence the discussion.
>>>>Cheers, Jack
>>>>
>>>>From: Chris Cole
>>>><chris.cole@xxxxxxxxxxx<mailto:chris.cole@xxxxxxxxxxx>>
>>>>Reply-To: Chris Cole
>>>><chris.cole@xxxxxxxxxxx<mailto:chris.cole@xxxxxxxxxxx>>
>>>>Date: Tue, 15 Nov 2011 17:33:17 -0800
>>>>To:
>>>><STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-100GNGOPTX@L
>>>>I
>>>>S
>>>>T
>>>>SERV.IEEE.ORG>>
>>>>Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
>>>>
>>>>Hello Jack,
>>>>
>>>>Nice historical perspective on the new reach space.
>>>>
>>>>Do I interpret your email as proposing to call the new
150m to 1000m
>>>>standard 100GE-MR4? ☺
>>>>
>>>>One of the problems in using today’s 100GE-LR4 cost as
a comparison
>>>>metric for new optics is that there is at least an order
of magnitude
>>>>variation in the perception of what that cost is. Given
such a wide
>>>>disparity in perception, 25% can either be impressive or
inadequate.
>>>>
>>>>What I had proposed as reference baselines for making comparisons
is
>>>>10GE-SR (VCSEL based TX), 10GE-LR (DFB laser based TX)
and 10GE-ER (EML
>>>>based TX) bit/sec cost. This not only allows us to make
objective
>>>>relative comparisons but also to decide if the technology
is suitable
>>>>for
>>>>wide spread adoption by using rules of thumb like 10x the
bandwidth
>>>>(i.e. 100G) at 4x the cost (i.e. 40% of 10GE-nR cost) at
similar high
>>>>volumes.
>>>>
>>>>Using these reference baselines, in order for the new reach
space
>>>>optics
>>>>to be compelling, they must have a cost structure that
is referenced to
>>>>a
>>>>fraction of 10GE-SR (VCSEL based) cost, NOT referenced
to a fraction of
>>>>10GE-LR (DFB laser based) cost. Otherwise, the argument
can be made
>>>>that
>>>>100GE-LR4 will get to a fraction of 10GE-LR cost, at similar
volumes,
>>>>so
>>>>why propose something new.
>>>>
>>>>Chris
>>>>
>>>>From: Jack Jewell [mailto:jack@xxxxxxxxxxxxxx]
>>>>Sent: Tuesday, November 15, 2011 3:06 PM
>>>>To:
>>>>STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-100GNGOPTX@LI
>>>>S
>>>>T
>>>>S
>>>>ERV.IEEE.ORG>
>>>>Subject: [802.3_100GNGOPTX] Emerging new reach space
>>>>
>>>>Following last week's meetings, I think the following is
relevant to
>>>>frame our discussions of satisfying data center needs for
low-cost
>>>>low-power interconnections over reaches in the roughly
150-1000m range.
>>>>This is a "30,000ft view,"without getting overly
specific.
>>>>Throughout GbE, 10GbE, 100GbE and into our discussions
of 100GbE
>>>>NextGenOptics, there have been 3 distinct spaces, with
solutions
>>>>optimized for each: Copper, MMF, and SMF. With increasing
data rates,
>>>>both copper and MMF specs focused on maintaining minimal
cost, and
>>>>their
>>>>reach lengths decreased. E.g. MMF reach was up to 550m
in GbE, then
>>>>300m
>>>>in 10GbE (even shorter reach defined outside of IEEE),
then 100-150m in
>>>>100GbE. MMF reach for 100GbE NextGenOptics will be even
shorter unless
>>>>electronics like EQ or FEC are included. Concurrently,
MMF solutions
>>>>have
>>>>become attractive over copper at shorter and shorter distances.
Both
>>>>copper and MMF spaces have "literally" shrunk.
In contrast, SMF
>>>>solutions
>>>>have maintained a 10km reach (not worrying about the initial
5km spec
>>>>in
>>>>GbE, or 40km solutions). To maintain the 10km reach, SMF
solutions
>>>>evolved from FP lasers, to DFB lasers, to WDM with cooled
DFB lasers.
>>>>The
>>>>10km solutions increasingly resemble longer-haul telecom
solutions. T!
>>>> here is an increasing cost disparity between MMF and SMF
solutions.
>>>>This
>>>>is an observation, not a questioning of the reasons behind
these
>>>>trends.
>>>>The increasing cost disparity between MMF and SMF solutions
is
>>>>accompanied by rapidly-growing data center needs for links
longer than
>>>>MMF can accommodate, at costs less than 10km SMF can accommodate.
This
>>>>has the appearance of the emergence of a new "reach
space," which
>>>>warrants its own optimized solution. The emergence of the
new reach
>>>>space
>>>>is the crux of this discussion.
>>>>Last week, a straw poll showed heavy support for "a
PMD supporting a
>>>>500m
>>>>reach at 25% the cost of 100GBASE-LR4" (heavily favored
over targets of
>>>>75% or 50% the cost of 100GBASE-LR4). By heavily favoring
the most
>>>>aggressive low-cost target, this vote further supports
the need for an
>>>>"optimized solution" for this reach space. By
"optimized solution" I
>>>>mean
>>>>one which is free from constraints, e.g. interoperability
with other
>>>>solutions. Though interoperability is desirable, an interoperable
>>>>solution is unlikely to achieve the cost target. In the
3 reach spaces
>>>>discussed so far, there is NO interoperability between
copper/MMF,
>>>>MMF/SMF, or copper/SMF.
Copper, MMF and SMF are optimized solutions. It
>>>>will likely take an optimized solution to satisfy this
"mid-reach"
>>>>space
>>>>at the desired costs. To repeat: This has the appearance
of the
>>>>emergence
>>>>of a new "reach space," which warrants its own
optimized solution.
>>>>Since
>>>>the reach target lies between "short reach" and
"long reach," "mid!
>>>> reach" is a reasonable term
>>>>Without discussing specific technical solutions, it is
noteworthy that
>>>>all 4 technical presentations last week for this "mid-reach"
space
>>>>involved parallel SMF, which would not interoperate with
either
>>>>100GBASE-LR4, MMF, or copper. They would be optimized solutions,
and
>>>>interest in their further work received the highest support
in straw
>>>>polls. Given the high-density environment of datacenters,
a solution
>>>>for
>>>>the mid-reach space would have most impact if its operating
power was
>>>>sufficiently low to be implemented in a form factor compatible
with MMF
>>>>and copper sockets.
>>>>Cheers, Jack