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Re: [HSSG] 40G MAC Rate Discussion


I can comment on the current availability of the QSFP transceivers which
is the near term candidate for the 4X10G transceiver. 10 gig optical
QSFPs are unavailable in shipping products.  The QSFP interface is
defined to run up to 10 Gig, but current products only run to 5 Gig.
This standard has only been out since December 1st, 2006, so expect
improvements in speed - probably even 10 Gig - to be coming soon. 10 Gig
QSFPs will definitely be out before the 100GE standard. You can find out
more about the QSFP at

There was some speculation about cost in an earlier e-mail and I would
like to comment on that.  I have heard that the cost of a 5 Gig QSFP are
comparable to the cost of a single XFP or approximately 10 4-Gig SFPs.
If the QSFP rolls out in relatively high volumes, the QSFPs are expected
to approach the cost of 4 SFPs at comparable speeds.  I would not expect
the QSFP to ever reach the cost of a single SFP since there are 4 SFPs
in a denser QSFP package. The parallel optics of the QSFP and expected
lower volumes will keep the cost higher than traditional manufacturing
techniques refined in the SFP that uses individual fibers. 

Scott Kipp
(no disclaimer)  

-----Original Message-----
From: Marcus Duelk [mailto:duelk@ALCATEL-LUCENT.COM] 
Sent: Friday, April 06, 2007 11:58 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