# Re: [802.3BA] XR ad hoc Phone Conference Notice

We can't compare 10 parallel MMFs to 1 SMF because 100G serial optics don't exist. What we have talked about on the SM side is 4x25, 5x20 and 10x10. While it is true that MMF is typically more expensive than SMF, it is also true that SMF optics are more expensive than MMF optics. Some of data we have seen:

Slide 12 of http://www.ieee802.org/3/hssg/public/nov06/peeters_01_1106.pdf

Slide 13 of http://www.ieee802.org/3/hssg/public/nov06/cole_01_1106.pdf

Slide 4 of http://www.ieee802.org/3/hssg/public/jan07/jewell_01_0107.pdf

Combining these three presentations and looking at what I believe are optimistic costs for ER optics:

10x10G SR is approximately 4 times 10GBASE-SR
10GBASE-ER is approximately 4 times 10GBASE-SR (I think this is optimistic)
5x20 LR is approximately 4 times 10GBASE-ER

Which means 5x20G LR will be  approximately 4 times 10x10G SR

Not an exhaustive analysis but a SWAG..........what we know is that the total cost of a MMF solution has always been lower cost than the total cost of a SMF solution - we can argue what the multiple of the SMF solution is.

Steve

Sent: Thursday, July 10, 2008 9:04 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] XR ad hoc Phone Conference Notice

Steve,

I agree that the objective states "at least 100m on OM3 MMF", but the question is what is the cost point for exceeding the 100m?  Can you provide data that shows the relative cost between 10 parallel MMFs vs. 1 SMF running 2-400m?

There was also another reason that 100m was seen as a good reach.  At these data rates, it may take a long time for a UTP or any twisted-pair solution to satisfy the typical 100m data center reach.  Failure to provide a cost effective solution for that market has a direct impact to the broad market potential.

Cheers,

From: Swanson, Steven E [mailto:SwansonSE@xxxxxxxxxxx]
Sent: Thursday, July 10, 2008 7:30 AM
Subject: RE: [802.3BA] XR ad hoc Phone Conference Notice

Just to be crystal clear, the objective reads:

"at least 100m on OM3 MMF"

While I agree that 100m meets that objective, Kolesar and I presented data in November 2006 noting that 100m was not adequate. We were assured that longer link lengths could be accommodated because of the words "at least." This was my beef in Munich.

In a survey of our customers 0/20 said that 100m was adequate and that MMF was preferred over SMF where possible.

I still don't understand why it is OK to have two link length objectives for SMF (and we considered a third (2-4km)) but we can't have two link length objectives for MMF. Better yet from my point of view is to have one PMD that satisfies both - the premium that we are talking about at the module level (estimated at ~20%) is in the noise for 40/100.

We need a compromise here of some sorts.

Steve

Sent: Wednesday, July 09, 2008 11:11 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] XR ad hoc Phone Conference Notice

That's an excellent point.  I'm glad that Jeff brought this up.

The objectives state 100m on OM3.  That is the requirement of the project and one by which the draft standard will be judged.  There is no requirement to satisfy a non-objective.

Thanks,

Sr. Principal Engineer, AMCC
bbooth@xxxxxxxx

From: Petar Pepeljugoski [mailto:petarp@xxxxxxxxxx]
Sent: Wednesday, July 09, 2008 9:51 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] XR ad hoc Phone Conference Notice

Frank,

If I interpret correctly, you are saying that all users should amortize the cost of very few who need extended reach.
We need to be careful how we proceed here - we should not repeat the mistakes of the past if we want successful standard.

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: Frank Chang To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx Date: 07/09/2008 10:29 PM Subject: Re: [802.3BA] XR ad hoc Phone Conference Notice

Hi Jeff;

Thanks for your comment. You missed one critical point that there is cost increase from OM3 to OM4. If you take ribbon cable cost in perspective, OM4 option is possibly the largest of the 4 options.

Besides, the use of OM4 requires to tighten TX specs which impact TX yield, so you are actually compromising the primary goal.

Frank

From: Jeff Maki [mailto:jmaki@xxxxxxxxxxx]
Sent:
Wednesday, July 09, 2008 7:02 PM
To:
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject:
Re: [802.3BA] XR ad hoc Phone Conference Notice

Dear MMF XR Ad Hoc Committee Members,

I believe our current objective of “at least 100 meters on OM3 MMF” should remain as a primary goal, the baseline.  Support for any form of extended reach should be considered only if it does not compromise this primary goal.  A single PMD for all reach objectives is indeed a good starting premise; however, it should not be paramount.  In the following lists are factors, enhancements, or approaches I would like to put forward as acceptable and not acceptable for obtaining extended reach.

Not Acceptable:
1. Cost increase for the baseline PMD (optic) in order to obtain greater than 100-meter reach
2. EDC on the system/host board in any case
3. CDR on the system/host board as part of the baseline solution
4. EDC in the baseline PMD (optic)
5. CDR in the baseline PMD (optic)

Acceptable:
1. Use of OM4 fiber
2. Process maturity that yields longer reach with no cost increase

In summary, we should not burden the baseline solution with cost increases to meet the needs of an extended-reach solution.

Sincerely,

Jeffery Maki

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Jeffery J. Maki, Ph.D.
Principal Optical Engineer
Juniper Networks, Inc.
1194 North Mathilda Avenue
Sunnyvale, CA  94089-1206
Voice +1-408-936-8575
FAX +1-408-936-3025
www.juniper.net
jmaki@xxxxxxxxxxx
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