Re: [HSSG] The List
Wenbin,
with regard to SFP+ volume, your note
basically states that SFP+ will find application at rates near 10G, not
at rates now served by SFP. So the volumes of SFP+ will not be driven
by displacement of the high volume SFP, but by what ever volumes exist
near 10G. Therefore I stand by my previous position that the analogy
to the 2G devices you drew are stretched thin at 10G rates because
the 10G volumes will be considerably smaller. The QSFP volumes at
2.5 and 5G lane rates will certainly assist in the total volume of common
components shared by all the rates packaged in the QSFP form. This
includes the housing, receptacle, possibly the PCB and many elements mounted
to the PCB, VCSEL and detector alignments, overall assembly, and many test
steps. The cost of the device is not simply controlled by the VCSEL
array.
There must be more factors than those
you have stated to convince me that the SFP+ has an undisputable and significant
advantage in volume projections relative to the QSFP.
Regards,
Paul Kolesar
CommScope Inc.
EnterpriseŽ Solutions
1300 East Lookout Drive
Richardson, TX 75082
Phone: 972.792.3155
Fax: 972.792.3111
eMail: pkolesar@commscope.com
| Wenbin Jiang <Wenbin.Jiang@JDSU.COM>
06/29/2007 09:37 AM
|
Please respond to
Wenbin Jiang <Wenbin.Jiang@JDSU.COM> |
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| Re: [HSSG] The List |
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Paul,
In the fiber channel (FC) market,
because of the cost parity, 2G quickly displaced 1G, and 4G is quickly
displacing 2G on the module side. Indeed, SFP is shared by both GE and
FC. Similarly, SFP+ volume will be a combined market of FC (8.5G) and 10GE.
The volume of QSFP at 10G and 20G will probably have little impact on the
40G, as they are going to use far lower speed lasers (2.5G to 5G).
Wenbin
From: Paul Kolesar [mailto:PKOLESAR@SYSTIMAX.COM]
Sent: Friday, June 29, 2007 6:36 AM
To: STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [HSSG] The List
Wenbin,
the material in kolesar_01_0507 explicitly states that volume was not factored
in, so the basis of disagreement you state is out of scope of that presentation.
That said, I fully agree, and have previously stated on this reflector,
that volume is a significant factor, and have asked for more disclosure
on volume assumptions. So thanks for adding to the discussion on
that front. Your statement that I had not properly accounted for
lower array yields seems counter to Chris Cole's assertions that 12-lane
transceivers would cost less than 2.5 times the 4-lane transceivers. Jack
Jewell has also made that assertion recently.
The comparison analogy you offer at 2G is interesting, but may be too skewed.
2G transceivers have come way down the cost curve relative to 10G
for reasons that go beyond volume at that particular data rate. The
SFP form is shared by many data rates from 1G to 4G, each contributing
to the volume of the common components. Indeed, some SFPs are data
rate agile. 10G volumes do not see anything close to the volume of
these combined lower rate applications, and there are other factors to
consider that I will touch on.
In order for the 2G analogy to apply well to the 10G rate, the SFP+ would
need to displace not only other 10G forms, but also the SFP. Is this
part of your volume assumptions? If not, then the volume argument
favoring SFP+ seems thin, since both the SFP+ and QSFP are new. SFP+
may have a lead in the market, but it is early in the conversion cycle.
QSFP does have multiple applications that span a wide variety of
data rates, such as the 10 and 20G (and future 40G) rates of InfiniBand
and current and future Fibre Channel rates at 10G, 20G, 34G and 40G, and
it offers much higher density. With the front panel surfaces of high-end
boxes completely packed with I/O, this density offers opportunity for relief.
With all this yet to play out, I am still unclear as to the assumptions
that support the assertions of volumes favoring SFP+. Can you offer
details to support that view, particually on the displacement of SFP?
Regards,
Paul Kolesar
CommScope Inc.
EnterpriseŽ Solutions
1300 East Lookout Drive
Richardson, TX 75082
Phone: 972.792.3155
Fax: 972.792.3111
eMail: pkolesar@commscope.com
| Wenbin Jiang <Wenbin.Jiang@JDSU.COM>
06/29/2007 01:29 AM
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Please respond to
Wenbin Jiang <Wenbin.Jiang@JDSU.COM> |
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| Re: [HSSG] The List |
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Paul,
I have reviewed your presentation, kolesar_01_0507. I do not agree with
you on the cost comparison between the 4xSFP+ and the QSFP. It has failed
to take the volume difference and low array yield into account. I would
expect that the SFP+ volume is going to be substantially higher and therefore
cost lower. Since 40G QSFP does not exist, a good benchmark is to compare
12 2G-SFP modules with a pair of 12-channel parallel 2.5G TX+RX modules.
One has a large volume base while the other is not. The low volume array
modules cost 2x to 3x of the high volume single channel modules.
Wenbin
From: Paul Kolesar [mailto:PKOLESAR@SYSTIMAX.COM]
Sent: Thursday, June 28, 2007 2:51 PM
To: STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [HSSG] The List
Wenbin,
my presentation from May, kolesar_01_0507, addresses my views on the intrinsic
costs of items 1, 3, and 4 of your list. Regarding item 2, I do not
know how to factor in the costs of reduced performance specs on SFP+, since
that gets too subtle. To me the issue was not if there could be cost
reductions for SFP+ PMDs but rather if SFP+ systems were capable of 10GBASE-S
performance. There have been statements that SFP+ meets 10GBASE-S
specs which imply that its cost improvements relative to XFP do not bring
with them significant performance impairments. If this is true for
a broad set of suppliers and systems, then there may be little benefit
in a reduced performance 10GBASE-S spec. Also the cost savings of
a reduced performance spec would be quite dependent upon which parameters
are relaxed and would likely be quite vendor-specific. So we may
end up with little added clarity in pursuing item 2.
In the pursuit of clarity, I have asked for criticism of kolesar_01_0507
and for disclosure on the impact of volume assumptions on others' relative
cost claims between 4xSFP+ and QSFP. I hope that through these additional
inputs a sufficiently complete picture emerges of the costs of the available
alternatives. I see these specific issues as better communicated
through discussion on the reflector than by presentation at the meeting.
But I am open to either approach. The latter at least has the
benefit of being counted as a contribution, although I think reflector
threads should also be included in such counts.
Regards,
Paul Kolesar
CommScope Inc.
EnterpriseŽ Solutions
1300 East Lookout Drive
Richardson, TX 75082
Phone: 972.792.3155
Fax: 972.792.3111
eMail: pkolesar@commscope.com
| Wenbin Jiang <Wenbin.Jiang@JDSU.COM>
06/28/2007 01:54 PM
|
Please respond to
Wenbin Jiang <Wenbin.Jiang@JDSU.COM> |
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| Re: [HSSG] The List |
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There are clearly confusions/questions on the economic feasibility of 40GE
100m objectives. Would appreciate a presentation to compare the relative
cost among the following:
1. 4x10G
LAG (10GBASE-SR compliant per lane, possibly 4 x SFP+ or QSFP, whichever
costing lower?)
2. 4x10G
LAG (relaxed spec from 10GBASE-SR, but similar to the 40GE per lane basis.
Possibly relaxed spec 4 x SFP+ or QSFP?)
3. 40GE
compliant (presumably QSFP?)
4. 100GE
compliant (SNAP12 TX+RX?)
Wenbin Jiang
From: Dove, Dan [mailto:dan.dove@HP.COM]
Sent: Thursday, June 28, 2007 8:52 AM
To: STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [HSSG] The List
Paul,
With regard to the point I made about a "relaxed spec for 10G"
vs writing an "entirely new Ethernet spec with multiple PMDs for 40G",
it was in response to your contention that 10GBASE-SR would be more expensive
to build than one channel of a new, unwritten, and parametrically relaxed
40G PMD. My point was not that it is *necessary* to have a relaxed spec
for 10G, but rather that if such a relaxation is to be done, it would be
less conflictive with existing projects to do a 10G PMD than an entire
set of PMDs and a 40G MAC spec that lacks distinction from 100G in the
market place. (ie: Two higher speed Ethernets coming out at the same time
with only a slight difference in speed)
It is my firm opinion that we can build 10GBASE-SR compliant SFP+ transceivers
and that the total solution cost compared to X2 or XFP will be significantly
lower in cost than today's solution cost because of the repartitioning
of the functionality, the rapidly diminishing cost of EDC, and the port
density improvements which will allow system vendors to distribute infrastructure
cost into more ports than is possible today.
Dan
From: Paul Kolesar [mailto:PKOLESAR@SYSTIMAX.COM]
Sent: Wednesday, June 27, 2007 4:40 PM
To: STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [HSSG] The List
Ali,
there seems to be a theme throughout your response that implies that cost
is paramount and compliance to 10GBASE-S is of secondary importance. This
subtle but very significant posture may be pervasive with others as well.
In my comparisons I have been holding 10G LAG implementations to
the requirements of 10GBASE-S. Dan suggested that a relaxed spec
version of 10GBASE-S could be an alternative that makes LAG more attractive
from a cost perspective. And I am asking Jack to clarify his statements
with respect to compliance. Now you make similar intonations. While
this may be an alternative, it is one that distorts the reality of the
day. We do not have a relaxed spec, and although it is possible to
conceive of such a change, there is no study group activity in that direction.
So it seems mostly academic at this point because proprietary solutions
of this sort do not ensure interoperability. We need to be very clear
on this assumption in our comparisons going forward.
Regards,
Paul Kolesar
CommScope Inc.
EnterpriseŽ Solutions
1300 East Lookout Drive
Richardson, TX 75082
Phone: 972.792.3155
Fax: 972.792.3111
eMail: pkolesar@commscope.com
| "Ali Ghiasi"
<aghiasi@broadcom.com>
06/27/2007 12:33 PM
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To
| "Jack Jewell" <Jack.Jewell@PICOLIGHT.COM>,
"Paul Kolesar" <pkolesar@systimax.com>
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| STDS-802-3-HSSG@listserv.ieee.org
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Subject
| Re: [HSSG] The List |
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Jack and Paul
The question is not whether SFP+ can achieve 300 m SR reach similar to
XFP, but how do we get to 10G SFP+
at 2.5x the cost of 1G classic SFP for DCE (Data Center Ethernet) with
max reach of 100 m.
If we can get to 10G SFP+ at 2.5x the cost of 1G at 300 m then the 10G
PAR objective is complete, but how long
do we wait the need is know. But I do know the combination of lower
cost optics with EDC can deliver
the 2.5x cost objective for DCE applications near term. To get to
these cost the transmitter very likely
will not be fully SR compliant and in that case it does not matter if the
reach is 100 or 300 m.
The current assumption in the HSSG is that you can achieve SFP+ limiting
performance with 4 or 10 channels without the
use of CDR in the module, with more crosstalk, less optimum layout, SerDes
having more jitter and less tolerance compare
to small port count PHYs, optics ??? You will get small benefit from
reducing fiber reach to 100m but not enough to close the
link budget. As Dan mentioned EDC is becoming an standard feature
on PHYs and we definitely need to leverage it for 40G/100G.
Use of linear interface is an approach that can close the link budget without
the use of CDR in the module, relax the optics
specifications, and the same interface can support passive copper Twin-ax
up to 10m.
Ali
Jack Jewell wrote:
Input from a transceiver vendor with experience and interest in both serial
and parallel modules:
First, SFP+ achieves the 300m SR objective with similar ease as XFP. While
a reduced-reach 10G PMD might reduce costs, it's a retreating approach
that requires the customer to purchase higher-cost transceivers to fill
in the reach gap, e.g. for reaches between 100m and 300m.. A reduced
operating temperature range offers immediate cost savings for some customers
without compromising reach and without any new standards specifications.
Use of a linear receiver and EDC and relaxed Tx specs can also achieve
the 300m reach at reduced cost. For this application, the amount
of compensation required is far less than what is required for LRM. EDC
is becoming widely available, to the point of being a standard feature
of PHY ICs, so the cost of this EDC is becoming insignificant. Forward-looking
standards efforts will achieve their full impact by making use of EDC.
For QSFP,. Here again, EDC offers great advantage, and ignoring it
would be a mistake. But crosstalk introduces module-level limitations
that might motivate reach reduction or other modification to the PMD.
Comparing costs, the SFP+ will be lower than QSFP for the forseeable future
(per lane for the same spec). The only advantage of QSFP over SFP+
is density and possibly simpler cabling. However, a 12-channel parallel
module pair, e.g. SNAP12, offers greater density than QSFP and 2.5-3X the
bandwidth at <2X the cost.
Jack
From: Dove, Dan [mailto:dan.dove@HP.COM]
Sent: Wednesday, June 27, 2007 9:32 AM
To: STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [HSSG] The List
Paul,
Regarding SFP+, I am very familiar with the technology and have been tracking
the SFF-8431 development. The architecture re-distribution of cost that
SFP+ offers will have a substantial impact on cost, especially when combined
with the higher density we can achieve with smaller geometry ASICs and
multiport PHYs that will come with it.
As for QSFP, I am less familiar with whether or not it will provide a cost
improvement over SFP+ or be capable of meeting the existing SR spec. This
is something for the QSFP experts to consider, but like I said, a shorter
10G PMD might be the avenue to take rather than an identity challenged
40G spec.
Regarding LAG, my conversation with HP Server architects indicates there
are a number of avenues for improvement of LAG under development.
I cited these areas in my earlier message and would appreciate them being
addressed rather than ignored.
Dan
From: Paul Kolesar [mailto:PKOLESAR@SYSTIMAX.COM]
Sent: Wednesday, June 27, 2007 8:04 AM
To: STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [HSSG] The List
Dan,
I can't tell how successfully SFP+ and QSFP will be at meeting the existing
10GBASE-S spec. If they can, a new shorter distance 10G PMD would
not be of value. If they can't, then a new PMD spec may be worth
while. Those attempting to implement these lower cost platforms need
to weigh in to provide guidance. In the event that either the QSFP
and/or SFP+ can meet 10GBASE-S specs in multiple vendor's platforms, or
that a new shorter distance spec is developed that allows lower cost, the
performance issues of LAG will remain. I believe Howard's presentations
on LAG have indicated that improving LAG would not be without compromise,
leading me to conclude that, however improved, LAG performance could not
become equivalent to a 40G pipe. Developing a 40G spec would ensure
a solution that simultaneously addresses these cost and performance issues.
Regards,
Paul Kolesar
CommScope Inc.
EnterpriseŽ Solutions
1300 East Lookout Drive
Richardson, TX 75082
Phone: 972.792.3155
Fax: 972.792.3111
eMail: pkolesar@commscope.com
Hi Paul,
Good points. I was not really expecting to see a significant cost differential
at the PMD although its a good argument that a 100m PMD would be less expensive.
If this is the case, why not do another 10G PMD focused on lowering the
cost of server interconnect? I believe that would be a smaller project
and have a much less significant impact on 100G development.
Thanks,
Dan
From: Paul Kolesar [mailto:PKOLESAR@SYSTIMAX.COM]
Sent: Tuesday, June 26, 2007 6:16 PM
To: STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [HSSG] The List
Dan,
thanks for your detailed thoughts and proposals. I appreciate the
points you made regarding the volume effect of 10G components on the cost
comparison. The presentation I submitted for the May interim looked
at the intrinsic cost factors and did not attempt to include volume in
the equation. But volume certainly can be a significant factor. Your
suggestion to look into its impact when comparing 4x10G LAG to 40G is reasonable,
but complicated at the PMD level. As my May presentation shows there
are a few ways to implement LAG on MMF. One uses the XFP, another
the SFP+, still another the QSFP. Today the XFP is shipping to the
10GBASE-S spec, and supports 300m transmission. Designs using SFP+
and QSFP will be more challenged to meet this spec due to jitter, so it
remains to be seen how successfully these lower cost form factors can substitute
for the XFP in 10GBASE-S compliant LAG. However, a reduced distance
requirement, such as that stated in the HSSG objectives, would greatly
improve the chances that QSFP will suffice for "40GBASE-S". So
while volume is important, these unanswered questions on suitability make
it impossible from my vantage point to determine how the volumes for 10GBASE-S
will be divided among XFP, SFP+, and QSFP. And the effects of volume
on production costs are better left to those who manufacture the devices.
Perhaps individuals with such insights will offer some scenarios.
Regards,
Paul Kolesar
CommScope Inc.
EnterpriseŽ Solutions
1300 East Lookout Drive
Richardson, TX 75082
Phone: 972.792.3155
Fax: 972.792.3111
eMail: pkolesar@commscope.com
My fellow colleagues ,
Last week I sent out a list of items that I felt need to be addressed to
ensure that a 40G PAR would be justified. At a subsequent EA teleconference
intended to build concensus in the HSSG, I offered to review the presentations
made in support of 40G Economic Feasibility and comparing 40G vs 4x10 LAG
performance to ensure that I was not being too harsh in my consideration
of the material that was presented.
Over the weekend, I reviewed every presentation I could find on these subjects
so that I could be comfortable that I was not being unfair in my concerns.
Fortunately, it was not a huge task as there are not that many to review.
After doing so, I found myself less convinced in the validity of
some presentations that were made. This statement is not made to criticize
my colleagues, but to honor the concept of peer review which requires that
we review and criticize, otherwise we might as well just upload them to
a server and forget about them.
Specifically, I disagreed with cost arguments made on the assumption that
10G cost remains a constant, when in fact I anticipate substantial reductions
in 10G cost over the next few years at a rate much faster than today due
to a few factors;
1) Higher density/lower cost optical form factors (SFP+) allowing better
utilization of switch infrastructural cost and QSFP for NICs.
2) Smaller geometry CMOS allowing higher port densities to work in synergy
with PMD cost reductions.
3) Integration of XFI / SFI interfaces directly into ASICs or multi-port
PHYs driving 10G cost further downward.
4) Higher volumes / commoditization of 10G driving cost down much faster
than the current trajectory.
While 40G can leverage some of these elements, it cannot leverage the volume
that feeds the downward cost spiral. So in 4 years, a 40G switch port cost
is going to be based on low-volume, freshly designed and un-amortized silicon
used primarily for server interconnect, whereas a 10G port cost will be
based on amortized, high-volume silicon being used in a huge array of applications.
Having different trajectories, the relative cost for 40G will be higher
than presented. This is true for 100G as well, but who is arguing a need
for 100G based on cost? It is bandwidth that drives 100G demand.
In addition, I found presentations claiming that LAG was insufficient to
address server I/O bandwidth needs, yet those presentations failed to address
upcoming technology enhancements like TRILL and its impact combined with
I/O Virtualization, perhaps with a physical manifestation of QSFP and MPO
optics which I believe can lead to graceful performance scaling for servers
that does not demand an intermediate IEEE standard. In other words, activities
and technologies are advancing which will parse server network access into
multiple conversations that can then be put onto a LAG group with much
higher than presented performance levels.
Now, I realize that I am swimming upstream here by asking that the proponents
for "40G now" to complete a task that took the 100G proponents
almost a year to accomplish, in less than 6 months, but then I am not asking
them to do that. My first choice, the one I proposed in Geneva,
was that we move 100G forward (because it is DONE) and that we continue
to work on 40G (until it is done).
This appears to be a minority position because apparently some people will
accept an unproven 40G proposal rather than risk 100G. Others think that
40G is proven sufficiently and are demanding "40G now" or they
will not allow a 100G PAR to go forward. Those in the latter camp must
either be unconvinced of my concerns, or they think my concerns are insufficient
to justify any further work being done to justify a 40G project.
I can accept differences of opinion.
What I cannot do, however, is pretend that these issues do not exist, or
that the work we would have to spend getting a 40G standard done is not
going to delay the much needed 100G aggregation solution our customers
demand. I cannot ignore what I perceive as holes in the 40G presentations.
So, to provide a little more direction to my colleagues in the "40G
now or the HSSG stalls" crowd, I am asking you to include relative
cost trajectories in your analysis of 40G vs 10G cost models, and to include
technology enhancements to LAG (TRILL, I/O Virtualization, QSFP, MPO) in
your performance analysis.
If you feel that this is unnecessary, I am requesting that you communicate
this position to me as soon as possible so that I can prepare a presentation
on these areas of concern for the July meeting.
Respectfully,
Dan Dove
Dove Networking Solutions - Serving ProCurve Networking by HP