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Re: [802.3BA] 802.3ba XR ad hoc next step concern



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,




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



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


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,



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.



-----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



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...






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.




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.   



Mike Dudek

PMTS Standards & Technology

JDS Uniphase

1480 Arthur Ave.


CO 80027

Tel  303 530 3189 x7533.




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.