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Hi Steve, Your response illustrates my point if one
examines the cost situation a bit closer. It is not sufficient to take a
broad brush view that the SM optics will retain a step function cost increase
relative to MM optics, because the magnitude of that step is critically important.
As I tried to show in my contribution at the last meeting in To me it not a question of if the SM
cost step will be reduced to 5x from its current magnitude, for all prior
Ethernet SM solutions have seen this occur. It is a question of
when. If the answer to “when” is projected to be so far into
the future that LR4 remains a hindrance to broad market potential during the
time when the market is projected to broaden, then that indicates we either
need another SM PMD with cost structures that can remove that hindrance, or we
need a MM objective that covers a greater portion of the longer length channels
than can be addressed with a 100 m solution. So for me its all about understanding the various
SM solution cost projections over time. Give me that information and I
can make a sufficiently informed determination on the optimal MM reach
objective. Regards, Paul 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: 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: 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
( 4438636577 ( Conference
Code: 207 012 5535 France,
Paris : 0170375518 Hong Kong,
Regards, Pete Anslow | Senior Standards Advisor |