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