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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 From:
Kolesar, Paul [mailto:PKOLESAR@xxxxxxxxxxxxx] 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] 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 From:
Chris Cole [mailto:chris.cole@xxxxxxxxxxx] 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] 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] 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] 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] 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. +44-203-4333547 (United Kingdom) 4438636577
(United States) Conference Code: 207 012 5535 Australia,
Melbourne : 0383380011 Australia,
Sydney : 0282386454 Austria,
Vienna
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All Cities :
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Zealand, Auckland
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Federation, Moscow : 4992701688 Singapore,
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Kingdom, All Cities :
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States, All Cities
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Ho Chi Minh : 84838012419 Regards, Pete Anslow |
Senior Standards Advisor |