Re: [HSSG] 40G MAC Rate Discussion
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
- 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.
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