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Re: [HSSG] 40G MAC Rate Discussion

Title: Re: [HSSG] 40G MAC Rate Discussion



The target for 40G is within the datacenter and there we would be perfectly happy with only one optical PMD for 100m on OM3 and one copper PMD for whatever length the copper folks can give us.


That’s all




From: Joel Goergen []
Sent: Friday, April 06, 2007 1:40 PM
Subject: Re: [HSSG] 40G MAC Rate Discussion



I share your concern and I would add a data point .... If I were to work on a 40Gbps MAC/PMD, I would press very hard for 100m, 10km, and 40km.  Since the market target for 40Gbps hasn't been clearly defined, the concept would have to address a wide range of implementations.

take care

John Jaeger wrote:

Yes, while Shimon has been clear on his need for a MMF only fiber PMD, there
absolutely have been comments and expressed interest in SMF PHY variants,
ranging from the 2/10km distance to even longer reaches.  I for one am very
concerned that if a 40G rate were to be added, given our previous history to
never err on the side of too few PMDs, the standard complete compliment of
PHYs would be specified before it's all said and done.


-----Original Message-----
From: Chris Cole [mailto:chris.cole@FINISAR.COM]
Sent: Friday, April 06, 2007 11:35 AM
Subject: 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