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Re: [HSSG] 40G MAC Rate Discussion


I agree and don't believe that the PHY is an issue, because as you
mentioned there are a lot of solutions out there already.  All of these
PHY's are transparent to the protocol and can be used in other standards
too; like the SFP is used for a lot of standards and the QSFP is also
referenced in the InfiniBand giving them a much broader market then for
Ethernet alone.


-----Original Message-----
From: Matt Traverso [mailto:matt.traverso@GMAIL.COM] 
Sent: Friday, April 06, 2007 11:29 AM
Subject: Re: [HSSG] 40G MAC Rate Discussion

Hi Marcus, Schelto,

As my company is not a member of the X40 MSA, I should not comment on
this directly.  However, my limited understanding of the potential
market environment for a 40GbE physical interface suggests that the
X40 would not fit comfortably in the servers that Shimon is

I believe that the server environment is more comfortable with a
physical interface which is similar in size and power dissipation
envelope to the QSFP, XFP, or SFP.  I believe that all of my
colleagues in the X40 MSA would agree that to achieve the power & size
for a SMF solution is challenging.  I don't believe that a lengthy
form factor discussion is appropriate or likely to be tolerated on
this thread, so this is why I'd like to understand as part of 40GbE's
BMP (broad market potential) effort the size / power / media

I'm going to stay out of the LAG discussion as my knowledge base
attenuates rapidly as we move up the protocol stack from the physical

--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.

On 4/6/07, Marcus Duelk <> wrote:
> Hi,
> 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 ...
> Marcus
> Matt Traverso wrote:
> > I'd like to comment from an optical component / module vendor point
> > 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
> > 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
> > the development quad laser drivers & quad amplifiers (or deka
> > & 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
> > 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
> > 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
> > of a low power interface IC -- this is the primary obstacle for
> > (40G SONET/SDH) modules
> > - A 4 lambda x 10G at single mode would not simply be able to plug
> > 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
> > 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