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Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective



I also see it as inevitable that there will be two variants:

"The first PMD would be optimized for lowest cost at maximum length; the second PMD would be optimized for maximum length at lowest cost."

 

Although 802.3 could ignore one, I don't think the market will.

 

It's worth discussing whether we expect these two things to be interoperable.

 

They might not be PMDs, they could be the same PMD with different PMAs (retimed or not) or FEC.

 

However, we know we don't know accurately enough how a staircase of increasing features/cost/power in the PHY relates to length.  Any objective for a particular length now is making a resolution that some particular length is more important than cost, power, size, or anything that is not an objective.  It is so important that it must be the answer, whatever the technology can deliver.  It is making a technical decision in the Study Group that the Task Force should make.  Much worse, it is making that decision when we know we don't know what it means (e.g. will it require faster lasers? FEC? DFE in the module?).  The length has to be a consequence of finding which step in the staircase of more complicated and expensive and power-hungry PHYs is too much, and then what reach can be delivered in the future with acceptable yield, before that step.

 

Steve's words point out what a more sensible pair of objectives would include:

one optimized for length;

one optimized for cost and power.

 

I have to take issue with Jack's "trend".  As I have said before, lasers don't follow Moore's Law; we are discussing different PHY architectures not a constant architecture but with faster silicon.  So we can't set objectives recklessly and rely on time to heal the wounds.

 

Piers

 

From: Jack Jewell [mailto:jack@xxxxxxxxxxxxxx]
Sent: 27 February 2012 02:55
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

I support standardizing these 2 Objectives. 

The first is a slam-dunk lowest-cost solution (no electronic "frills") for growing-and-important HPC and copper-replacement applications. The second takes into account the general trend that well-targeted objectives-set-now may appear hard now, but become practical by the time volume markets mature.

Cheers, Jack

 

From: "Swanson, Steven E" <SwansonSE@xxxxxxxxxxx>
Reply-To: "Swanson, Steven E" <SwansonSE@xxxxxxxxxxx>
Date: Sun, 26 Feb 2012 17:03:41 -0500
To: <STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

Dan etal,

 

I also support Jonathan’s effort to conduct the a straw poll on the MMF objectives and have responded to Jonathan with the same proposal that I sent to the broader reflector last week, namely:

 

Define a 4-lane 100 Gb/s PHY for operation over OM3 MMF with lengths up to at least 50 m

 

Define a 4-lane 100 Gb/s PHY for operation over OM4 MMF with lengths up to at least 150 m

 

I wanted to provide some more rationale for why I chose these two objectives as opposed to the 100m objective on MMF that so many seem to favor. I could not support a 100m objective over MMF because I don’t believe that it optimally addresses either of the two customer requests that I have heard since the formation of the SG. We have to remember that the goal of this SG is to establish objectives leading to cost effective 100G solutions. I believe the current solution, 100GBASE-SR10 (supporting 100m on OM3 and 150m on OM4) is cost effective and that is supported in that we are using it as the baseline for comparison of all other PMDs. The current estimates for 100GBASE-SR4 have typically come in at 1.2x 100GBASE-SR10 providing further support for its cost effectiveness. We believe, however, that long term that 100GBASE-SR4 will be more cost effective than 100GBASE-SR10.

 

So the real question is what link length objective(s) should we set for 100GBASE-SR4? I would argue that it is not 100m. I don’t believe that we can get to 100m with the lowest cost transceiver, thereby requiring those customers who do not need 100m to pay for something they don’t need. Our modeling suggests that we can’t get to 100m on OM3 or OM4 fiber with the current transceiver design without adding cost. I think we can support 50m without adding cost. Second, 100m does not meet the minimum link length requirement for a significant percentage of data center customers, thereby denying them a standard solution even if that solution is much more cost effective than a SMF solution that will support the same length. We get calls on a regular basis to support link lengths longer than what is specified in IEEE; we recently revised to 10GBASE-SR spec to include OM4, achieving longer link lengths. Finally, we need a solution that at least supports what we just specified in 100GBASE-SR10 that supports 100m on OM3 and 150m on OM4. I believe an objective that supports 150m on OM4 will support 100m on OM3.

 

We can continue to analyze models and gaze into crystal balls, but I don’t think it will change the answer much. We should set the objectives to address our customer needs and then determine how to meet those objectives in the Task Force.

 

So I agree with Petar Pepuljugoski here - the users should speak up on this. I believe that there is merit for two PMDs for MMF.

 

The first PMD would be optimized for lowest cost at maximum length; the second PMD would be optimized for maximum length at lowest cost.

 

Best regards,

 

Steve

Steven E. Swanson
Corning Incorporated
800 17th Street NW, HI/ES
Hickory, NC 28603-0489

t       828-901-5328
f       828-901-5533
c       607-725-1129

swansonse@xxxxxxxxxxx

From: Daniel Dove [mailto:ddove@xxxxxxx]
Sent: Friday, February 24, 2012 12:17 PM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

Jonathan,

I support your effort to straw poll the group.

We all have to keep in mind that the goal of a Study Group is to set objectives and justify them with the 5 criteria responses.

Our job is not to get 100% agreement, but to get consensus. If we can get 75% of the room to agree that any particular reach on MMF will have broad market potential, is technically feasible and cost effective relative to alternatives in the market, we can move into Task Force and figure out exactly how far, how to do it, etc.

Rather than an extended debate on the reflector, I would prefer to see presentation requests identifying an objective and showing why that objective is absolutely essential.

Jonathan's straw polling is intended to provide direction on where presentations should focus. If we have consensus on any particular objective, it would be better to develop presentations around that, than spend our time working on an objective some people might feel is important but cannot gain consensus.

Lets figure out where consensus can be achieved and work toward that.

Dan

On 2/24/12 8:14 AM, Alan Flatman wrote:

I  support Pete and am also in favour of setting the objective to be 100m over MMF and leave the technical choices as to whether this means over OM3 or OM4 etc. to the TF.

 

Regards,  Alan

----- Original Message -----

Sent: Friday, February 24, 2012 3:54 PM

Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

Paul,

 

While I am not saying that 150m over OM4 may not be the outcome of the Task Force, it is my view that it is not the function of the Study Group to start to make technical choices for the Task Force.  I think the Study Group should set an objective at which the PMD has broad market potential etc. and try to make as few technical choices as possible.  150m over OM4 is quite a challenging objective and setting it would rule out some of the choices that the Task Force might want to make.  I am not of the view that if it turns out to be 100m over OM4 that this is not worth doing, so I  am more in favour of setting the objective to be 100m over MMF and leave the technical choices as to whether this means over OM3 or OM4 etc. to the TF.

 

Regards,

Pete Anslow | Senior Standards Advisor
43-51 Worship Street | London, EC2A 2DX, UK
Direct +44 2070 125535
|

 

From: Kolesar, Paul [mailto:PKOLESAR@xxxxxxxxxxxxx]
Sent: 24 February 2012 15:31
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

Pete,

The line of thinking expressed in your second paragraph suggests that the MM reach objective would need to be revisited, presumably to be shortened for lower cost, should the SM PMD cost be projected to be low enough to cause it to be attractive for channel lengths within that MM reach.  If my interpretation is correct, and we do not have confidence in SM optics achieving such an aggressive cost decline, then the reach objective for MM should be at least as long as that established for 100GBASE-SR10, namely 150 m on OM4.  

 

Regards,

Paul

 


From: Anslow, Peter [mailto:panslow@xxxxxxxxx]
Sent: Friday, February 24, 2012 9:10 AM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

Chris,

 

I don’t think that this really helps.  What you really need to know in order to determine if an SMF PMD will affect what the reach should be for the MMF objective is the relative cost of the new MMF and SMF modules.  However, just knowing what the SMF reach objective is won’t tell you that.  Many of the decisions to be made by the Task Force will affect this relative cost and there was some consensus on the last SMF call that the only likely constraint on an SMF objective below say 2 km is the cost of parallel fibre.  It is not clear at this point whether a PMD capable of 1km (say PAM-8) is more expensive or cheaper than one that is only capable of 500m (say parallel fibre).

 

I think that the Study Group should decide on a MMF objective that stands on its own.  If it turns out that there is an SMF objective and the Task Force choices make the relative cost of that PMD low enough to affect the MMF reach, then the Task Force can seek to change the MMF objective.  This is (in my opinion) the earliest point that the group can rely on having a reasonable idea of the relative cost of the two solutions.

 

Regards,

Pete Anslow | Senior Standards Advisor
43-51 Worship Street | London, EC2A 2DX, UK
Direct +44 2070 125535 |

 

From: Chris Cole [mailto:chris.cole@xxxxxxxxxxx]
Sent: 24 February 2012 14:47
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

Steve

 

I tend to agree with you, but Paul does have a point that to some knowing what the SMF objective is important in deciding what the MMF objective should be.

 

My suggestion is that we keep the MMF poll exactly as Jonathan crafted it. Anyone that feels the SMF objective has to be decided first has the option to state so and then state their view of what that is likely to be. This will allow us to not delay making progress towards reaching consensus on a MMF objective

 

So let’s call this question A.

 

A)     To make a decision on an MMF reach objective, I am assuming the SMF reach objective will likely be:

a.      No SMF objective

b.      At least 500m

c.      At least 1000m

d.      At least 2000m

 

Those like you and me who do not see strong linkage simply do not answer question A.

 

Jonathan can then record how many responses he receives to question A and the choice. Both results will give us a measure of the thinking of Ad Hoc participants.

 

Chris

 

 

From: Trowbridge, Stephen J (Steve) [mailto:steve.trowbridge@xxxxxxxxxxxxxxxxxx]
Sent: Friday, February 24, 2012 6:14 AM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

Hi Paul,

I don’t think it is nearly so clear that you should decide SM first.

 

If there existed a SM solution that was cost-competitive with a MM solution at some reach, it would be a game changer, and those developing MM solutions would surely like to know if the game will change before getting too far down the path. But most seem to believe that the game will not change, and even if it did, it is hard to prove because it is difficult to compare relative costs of dissimilar technologies.

 

Most still seem to believe (in spite of the interesting technology from Opnext) that there will be a significant step function from MM to SM that will keep people from wanting to use it in data centers. Furthermore, if you need a different cable type, for example, for a 70m link than you need for a 100m link, that creates its own kind of problem.

 

So if the game does not change, then SR4 needs to try to address most, if not all, of the reach currently addressed by SR10. If it turns out not to be technically or economically feasible to do that (e.g., if you could only get 60 or 70m out of the beast within reasonable cost, size and power), then if SM is to replace MM above that reach, it needs to get down to a cost to compete with an SR10 with a reverse gearbox. Even if SM does this, it isn’t clear they will get all of that market because of a likely reluctance to mix cable types in the data center – maybe they are happier to use SR10 with a reverse gearbox to reuse their existing cabling.

Regards,

Steve

 

From: Kolesar, Paul [mailto:PKOLESAR@xxxxxxxxxxxxx]
Sent: Friday, February 24, 2012 6:49 AM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective

 

Jonathan,

While I understand the desire to find a launching point for the discussion, this poll is approaching the problem in the wrong order because we need to know what the single-mode objective is first.  

 

A purpose of the Study Group is to set objectives that will allow us to establish cost-optimized 100GE.  One cannot logically pick cost-optimized MM objectives without first having framework around the SM optics that will be used to address channels with lengths that exceed the MM reach.  At this point, we have not even established if we will have a SM objective.  In other words, we don’t know if the existing LR4 will remain the only one, or if there will be another one added.  Only when the SM situation is established can we know the minimum capability that a new MM optic must fulfill to optimize cost.

 

I suggest that we first conduct such a poll for SM and use it to start the objective discussion in the SM ad-hoc.  If that produces solid results, then undertake the same endeavor for MM.

 

 

Regards,

Paul

 


From: Jonathan King [mailto:jonathan.king@xxxxxxxxxxx]
Sent: Thursday, February 23, 2012 8:13 PM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF and MMF Ad Hoc meetings: MMF objective
Importance: High

 

Dear all,

On the Feb 14th MMF ad hoc call , it seemed like we were  beginning to converge on a possible objective for MMF .

In the next meeting (Tuesday 28th Feb), I’d like to see if we can finalize a strawman MMF objective.  To that end I’ll prepare  a presentation which we can review  during the call which will include a strawman objective for review on the call, together with an overview of how it addresses the 5 criteria – to help get the best starting point for that discussion I’d like to get your responses to the questions below  questions:

 

The strawman objective will follow the wording in Anslow_01_0111

 

Define a 4-lane 100 Gb/s PHY for operation over OMX MMF with lengths up to at least Y m

 

 

1)      A reasonable MMF reach objective (i.e. the value of Y) would be

a.      100m

b.      Significantly less than 100m (what reach?)

c.      Significantly more than 100m  (what reach ?)

d.      decided in the task force

 

2)      The MMF type should be

a.      decided in the task force

b.      OM3

c.      OM4

d.      at least as good as OM4

 

Please send your responses to me directly at:  jonathan.king@xxxxxxxxxxx

I will collate and report the results but will not reveal any individual’s responses.

If you feel uncomfortable expressing an opinion, say so and I’ll note that.

 

To  repeat, this is not a formal poll or vote, just intended to give us the best starting point for discussion on Tuesday.

Please send your responses as soon as possible, and at least by close of business on Monday 27th Feb, 2012

Many thanks !

 

Jonathan King

MMF ad hoc chair, Next Gen 100G Optics

 

From: Anslow, Peter [mailto:panslow@xxxxxxxxx]
Sent: Wednesday, February 22, 2012 2:10 AM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: [802.3_100GNGOPTX] SMF Ad Hoc and MMF Ad Hoc meetings

 

Hi,

 

Following on from the meetings on 14 February, Jonathan and I are planning to hold an SMF Ad Hoc meeting immediately followed by an MMF Ad Hoc meeting (1 hour each) starting at 8:00 am Pacific on Tuesday 28 February.

 

If you would like to present a contribution at the SMF ad hoc, please send it to me and for the MMF ad hoc, send it to Jonathan.

 

Peter Anslow from Ciena has invited you to join a meeting on the Web, using WebEx. Please join the meeting 5-10 minutes early so we may begin on time.

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Topic: "SMF Ad Hoc followed by MMF Ad Hoc"

Date & Time: Tuesday, 28 February 2012 at 16:00, GMT Time (London, GMT)

To join web meeting click here: https://ciena.webex.com/ciena/j.php?ED=136667227&UID=0&PW=NMGZjOWUwNDM2&RT=MTgjMjE%3D

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Regards,

Pete Anslow | Senior Standards Advisor
43-51 Worship Street | London, EC2A 2DX, UK
Direct +44 2070 125535 |