Ryan,
Thank you for the clarification. 10mW
extra per channel for a 10G CDR is an incredible number – and I mean it
in an entirely complimentary way.
BTW, I do support the CDR option insomuch
as I support the whole XR activity – just want the group to be clear on
what’s involved. I personally think it may require a different module
than QSFP/CSP currently considered for SR4/SR10 and CR4/CR10..
Gourgen
From: Ryan Latchman
[mailto:Ryan.Latchman@xxxxxxxxxx]
Sent: Tuesday, September 02, 2008
10:31 AM
To:
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR
ad hoc next step concern
Hi David, Gourgen,
Thank you for the
response. For XR, the group already has our opinion on the additional
power consumption for CDR functionality. I am not talking about 4W/10W
per each end of cable assembly.
I can’t give exact
power consumption numbers due to competitive reasons. With respect to
further evidence on the power consumption side, I can tell you that
Gennum’s Quad CDR with Limiting Amplifier IC (test chip results have
already been shared for XLAUI and 4x10G SMF presentations) will consume less
than 40mW more per channel compared to stand alone limiting amplifiers used in
SFP+. In follow on generations, this difference will continue to
reduce. Similar deltas can be observed in the transmit direction.
I agree with respect to
not spending time on SFP+, and focusing on 40/100GbE. I am not proposing
to make CDRs a requirement. I am presenting this as an option for
achieving XR reach.
Best Regards,
Ryan
From: Gourgen
Oganessyan [mailto:gourgen@xxxxxxxxxxx]
Sent: September 2, 2008 10:50 AM
To:
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR
ad hoc next step concern
I would agree with David. Also, we
shouldn’t lose the sight of what we’re talking about: not 10G SFP+,
but a 40G/100G solution. So if it’s 1W, you’re talking 4W/10W per
each end of cable assembly.
Gourgen
From: David Nelson (
Sent: Tuesday, September 02, 2008
9:20 AM
To:
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR
ad hoc next step concern
To say the power of an
sfp+ with dual cdr is less than 1W is not very helpful,
considering 10G sfp+ modules range from under 0.5W to nearly 1W
already. If your module including cdr is substantially below 1W, you
would be wise, for the sake of furthering your company goal of getting a spec
written to include a cdr, to get your company's permission to divulge that
information. If the module power with cdr is close to 1W, as many of us
suspect, then for many module vendors that would represent a substantial
increase in module power, and the requirement to include dual cdr's is not
persuasive.
David Nelson, JDSU
From: Ryan
Latchman [mailto:Ryan.Latchman@xxxxxxxxxx]
Sent: Tuesday, September 02, 2008
5:58 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR
ad hoc next step concern
Hi Paul,
Sorry, I can’t
divulge that information. What I can say is that there is margin with
respect to SFP+ 1W requirement.
Best Regards,
Ryan
From: Paul Kolesar
[mailto:PKOLESAR@xxxxxxxxxxxx]
Sent: August 31, 2008 8:41 AM
To:
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR
ad hoc next step concern
Ryan,
what is the typical and maximum power dissipation of the
SFP+ module with the integrated CDRs that you show below?
Regards,
Paul Kolesar
|
Ryan Latchman
<Ryan.Latchman@xxxxxxxxxx> 08/30/2008
09:04 AM
|
|
Ali,
As previously discussed, your comparison
with XFP is flawed. The cost and power estimates given for XR assumes CDR
integration which is very feasible. For your reference, below is an
example PCB of an SFP+ module with CDRs in both directions (CDR with integrated
laser driver in the Tx direction, CDR with integrated limiting amplifier in Rx
direction). The benefits of this are clear. Systems designers don’t
need to worry about jitter budgets (a topic which has plagued SFP+), and it
saves them from having to put standalone signal conditioners on the line card,
saving material amounts of cost and total system power.
The CDR based solution for achieving
extended reach is the most trivial solution since:
1) It uses a simple host interface (XLAUI / CAUI)
which can be leveraged to achieve all types of 40GbE or 100GbE PMD interconnect
2) XLAUI / CAUI enables lots of design flexibility.
Hosts don’t care that the MMF channel is longer.
3) It is well proven technically.
Sorry I missed the XR call, but I was on a
plane at that time. I look forward to additional discussion on this
topic.
Best Regards,
Ryan
From:
Ali Ghiasi [mailto:aghiasi@xxxxxxxxxxxx]
Sent: August 29, 2008 3:48 PM
To: Ryan Latchman
Cc: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx; DAWE,PIERS; Booth, Bradley
Subject: Re: [802.3BA] 802.3ba XR ad hoc next step concern
Ryan
If you compare the cost difference between XFP and SFP module you will find
more than 50% cost difference.
Adding a CDR to an SMF module will add about 5% to the BOM and about 15% to an
MMF module BOM.
As you know the final cost of the module will increase by greater amount than
the BOM cost increase.
You assumption about integrating CDR in the LA/LD may require to use special
process, may limit availability, may have
technical issue of integrating TIA in to a CDR, or may have physical constrain.
During the XR call yesterday we had discussion how the system cost increase if
the port density is reduced my be the greatest cost
factor.
Thanks,
Ali
Ryan Latchman wrote:
Hi Piers,
When considering the 5% cost adder to the
module, take a look at the delta area of adding CDR functionality to a limiting
amplifier or laser driver. I think you will find the extra area is small,
particularly when you take into account bond pads of the LA/LD. Now take
into account the other components which contribute to the cost of the module
(ROSA, TOSA, uC…). I think you will find that a 5% adder is very
realistic.
Best Regards,
Ryan
From:
DAWE,PIERS [mailto:piers.dawe@xxxxxxxxxxxxx]
Sent: August 28, 2008 12:15 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR ad hoc
next step concern
Hi Brad,
The 5% sounds unlikely (I would have
expected more) and similarly the 17% (what I've seen of the surveys says that
when invited to lay out equipment anywhere with a 300 m constraint, very few
links even go beyond 100 m).
But I'm actually writing to reply to your
paragraph about compliance points. Remember that for Gigabit Ethernet, in
38.5, Table 38-10, the Total Jitter at TP1, TP2, TP3 and TP4 are all normative.
Piers
-----Original Message-----
From: Brad Booth [mailto:bbooth@xxxxxxxx]
Sent: 28 August 2008 03:55
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR ad hoc
next step concern
Dave,
I agree. A 5% cost adder seems
reasonable for a 17% increase in broad market potential.
I do wonder if part of the problem is the
compliance points TP0, TP1, TP1a, TP4, TP4a and TP5. In past efforts such
as 802.3z and 802.3ae, these compliance points have been left up to MSAs and
only TP2 and TP3 were of concern. Now the task force is dealing with such
issues as modules and the cost impact of various implementations. IMHO,
IEEE 802.3 was trying to avoid writing implementation specifications and was
focused on compliance specifications. Could it be that these compliance
points are causing the task force some heartache because it results in an
implementation specification?
Just food for thought...
Thanks,
Brad
From:
Chalupsky, David [mailto:david.chalupsky@xxxxxxxxx]
Sent: Wednesday, August 27, 2008 8:18 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR ad hoc
next step concern
The 20% cost premium applies to only one
of our proposed XR alternatives.
According to the alternatives spreadsheet
(Comparisons_xr_01_0708.xls) the CDR option adds only 5% module cost premium
over the base proposal and provides reach of 168m to 251m (across the OM3/4,
one-sided/two-sided matrix).
I’m struggling to keep up with the
conversation here – but I believe that the 5% alternative addresses the
same problem as the 20% alternative, right?
On that assumption I will rephrase
Dan’s non-rhetorical question to address a 5% cost adder for 17% increase
in coverage:
If I have the choice between:
A) carry two product SKUs: 100m and 150m,
with 5% Bill of Material cost delta on the 150m product; or
B) carry only the 150m product
I would accept option B & use only the
150m module even though I know that most of my customers will use it at
<100m.
By considering only the bill of material
of the module we are missing two aspects of the big picture on cost.
1) Carrying multiple product SKUs through
design, validation, manufacture, customer qualification, customer confusion,
etc. adds cost.
Regardless of whether 802.3ba adds a
second objective, if the module supplier base develops two different module
solutions for 100 & 150m, then the 100m solution will carry an intangible
cost burden and the desired 0% cost adder for 100m will not be achieved anyway.
2) The module is not the whole solution.
The CDR module solution does not add cost to the host. Thus a 5%
increase in module cost is less than 5% increase in the total cost of the
switch plus modules.
I appreciate that the task force is
learning from the history of 10GBASE-SR: that over-specifying the solution had
a long term cost impact.
However, we should take away another
lesson from 10Gbit: that providing too many options confuses the
customers & slows adoption.
I strongly urge the task force to provide
a single solution for parallel MMF. I believe that it’s worth a 5%
cost adder to the module to achieve that.
I really have no personal (or commercial)
reason to prefer the CDR option. I’m just looking at the 5% figure
in the spreadsheet & wondering why this isn’t a no-brainer.
Thanks for your time,
Dave Chalupsky
From:
Dove, Daniel [mailto:dan.dove@xxxxxx]
Sent: Wednesday, August 27, 2008 4:49 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR ad hoc
next step concern
Hi Mike,
We are pretty close to full circle now. :)
Assuming we make the decision that we want
to stick with the "standard" model at 100m to keep those customers we
would lose by adding cost, does the IEEE standardize a 150m solution or do we
let the market solve that problem on its own?
This is not a rhetorical question,
although it might appear to be.
Can someone provide any insight on the
sensitivity of the market to an additional cost of 20% for every 100m link to
satisfy the additional reach?
If the market is insensitive to cost (on
this scale) then perhaps the additional reach is justified. If the market is
going to be sensitive to that differential cost, then the question falls back
to whether the IEEE wants to do a 150m spec or leave it to a market-defned
solution.
Dan
From:
Mike Dudek [mailto:Mike.Dudek@xxxxxxxx]
Sent: Wednesday, August 27, 2008 4:22 PM
To: Dove, Daniel; STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3BA] 802.3ba XR ad hoc
next step concern
Hi Dan
Of course if we don’t increase the
cost of the basic Grade A model and have a Grade B version of the same part for
extra reach with the Grade B version being loaded with any additional costs of
handling two product codes and any additional testing, then we shouldn’t
lose any customers.
Regards
Mike Dudek
PMTS Standards & Technology
JDS Uniphase
Tel 303 530 3189 x7533.
mike.dudek@xxxxxxxx
From:
Dove, Daniel [mailto:dan.dove@xxxxxx]
Sent: Wednesday, August 27, 2008 3:23 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR ad hoc
next step concern
Let me re-state one word of that message.
From:
Dove, Daniel
Sent: Wednesday, August 27, 2008 2:00 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] 802.3ba XR ad hoc
next step concern
Hi Steve,
Yes that helped a lot. I hope the others
on the list are not irritated by my request for repetition of the data.
Given the data, it truly is a challenging
issue. I see a 20% premium for a 17% increase in coverage.
This means the confidence in the numbers
is exceptionally important and assuming they are accurate, a judgement call by
the committee on whether or not a 17% increase in port coverage justifies the
20% increase in cost.
This is important because if you increase
the *COST* of a solution by 20%, you may decrease the number
of customers who are willing to buy it by more than 20%. Thus, in the overall
mix, it might turn out to satisfy less customers overall.
Its a pretty challenging judgement call
IMHO.
Thanks for providing the data.
Dan