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Re: [HSSG] 40G MAC Rate Discussion

To date, the only optical PMD that has been mentioned as required for
the 40GE application is ~100m OM3 MMF reach, which leads to a 4x10G
single 12-ribbon MPO cable approach, as detailed by Matt Traverso in his
email. I am copying Shimon Muller's Aril 3 email to the reflector, which
re-iterates this point. 

As mentioned the 100GE ~100m OM3 reach optical specification that will
be standardized, could be directly used for a 40GE ~100m OM3 reach. Even
if the IEEE does not adopt a 40GE PMD, 4x10G ribbon fiber optical module
implementations (like QSFP) can still reference the future 100GE ~100m
OM3 specification, and have a standardized, public, interoperable
optical link budget.


-----Original Message-----
From: Shimon Muller [mailto:Shimon.Muller@Sun.COM] 
Sent: Tuesday, April 03, 2007 11:45 AM
Subject: Re: [HSSG] 40G MAC Rate Discussion

>The per lane optical link specification that we will develop for the
>100GE 100m (or greater) OM3 ribbon MMF reach objective can be the same
>for 10x10G or 4x10G application. The 10x10G link may require a slightly
>higher cross-talk penalty then 4x10G, but that is not enough to have
>separate specifications.

This has been my assumption all along.
This is also THE ONE AND ONLY optical PMD that I believe would be
absolutely required for 40Gb. The other one that we would need for
server connectivity is a very short-reach (10m-15m) copper cable.


-----Original Message-----
From: Marcus Duelk [mailto:duelk@ALCATEL-LUCENT.COM] 
Sent: Friday, April 06, 2007 10:58 AM
Subject: Re: [HSSG] 40G MAC Rate Discussion


aren't there already 40G (i.e. 4x10G) transceiver out there ?
I know at least of one transceiver company that is offering these
devices today, there is also the X40 MSA group:

So I get the impression that the PMDs (including SMF) are
already existing, it is maybe more a matter to have a MAC
that supports this as one logical 40G pipe. But then we are
back at that discussion what the difference to 4x10G LAG is,
I assume ...


Matt Traverso wrote:
> I'd like to comment from an optical component / module vendor point of

> view.
> Personally I'm not convinced that broad market potential has been
> demonstrated, but... Operating under the assumption that the 40GbE
> broad market potential is verified with end user input:
> - As we heard/saw in Jack Jewel's presentation focused on the cost &
> reliability of the MMF objective, extending from a 1x10G VCSEL to a
> 10x10G VCSEL does not represent a linear cost increase -- similarly a
> 4x10G would only be an incremental increase
> - The dominant cost in a nx10G MMF interface is likely to be any
> premium charged for the interface IC as well as costs associated with
> the development quad laser drivers & quad amplifiers (or deka drivers
> & amps)
> - I'd like to hear a comment / perspective from the fiber
> manufacturers on the utilization rate of the ribbon fiber strands.
> For a 4x10G MMF approach presumably 8 strands in the 12 ribbon would
> be used 4 for TX and 4 for RX.  For a 10x10G MMF approach it would be
> 2 @12 with 10 @ Tx and 10 @ RX.  What does this do to the cost and
> usage rate metrics of MMF cabling?
> - Would an SMF PMD objective at 40GbE have broad market potential
> (BMP)?  Here I am very skeptical
> - Assuming that BMP was shown for an SMF PMD objective, I would
> advocate a 2km serial 40Gbit/s scheme rather than a 4 lambda approach
> as the transmission problems are not as severe
> - This would represent the path that reuses the most technology and
> allows for a compact & low power dissipation end solution
> - As I have stated one of the primary impediments is the availability
> of a low power interface IC -- this is the primary obstacle for OC768
> (40G SONET/SDH) modules
> - A 4 lambda x 10G at single mode would not simply be able to plug in
> the work done on 802.3ae as the technical challenge of MUX/DMUX
> optical loss and packaging would require a new round of investment
> In closing I'd like to see some supporting data for the Broad Market
> Potential of 40GbE (including distance / media usage
> comments/assumptions) that reflects the timeframe of standard
> development -- eg. demand/need in 2009-2012.
> thanks,
> --matt traverso
> NOTE: This e-mail is being sent from my personal e-mail account rather
> than my corporate e-mail address at Opnext due to default signature
> files embedded in my Opnext e-mail account.

Marcus Duelk
Bell Labs / Alcatel-Lucent
Crawford Hill HOH R-237
791 Holmdel-Keyport Road
Holmdel, NJ 07733, USA
fon +1 (732) 888-7086
fax +1 (732) 888-7074