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Re: [HSSG] 40G MAC Rate Discussion


The current X40 is based on Xenpak MSA and was meeting the initial market
requirement.  During the development of X40 at one point I proposed to 
start with X2.
Currently LX4 module exist with each lane operating at 3.125 Gb/s, so 
the question here
is what would it take to increase the laser speed to 10G/lane? 

Another data point we can use is the fact you can get LRM/LR SFP+ module 
with <1W,
where X2 module is about 700% larger than SFP+ module.  Can you 
repackage 4 SFP+
module in to an X2?

Imagine the technology required and time frame to support 100G on 
servers requiring

I did see Demo of QSFP at OFC operating at 5 Gb/s and some work has 
already been done
to operate QSFP at 10Gb/s/lane.


Matt Traverso wrote:
> 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
> envisioning.
> 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
> requirements.
> 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
> interface.
> 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.
> 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 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

fn:Ali Ghiasi
adr;dom:;;3151 Zanker Road;San Jose;CA;95014
title:Chief Architect