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Ben,
This
is not JUST a project for the access network and that is not the "whole reason
they exist". 100BASE-LX10 and 1000BASE-LX10
like PHYs existed before EFM, and we should be standardizing
them right. We have known all along that they have general
applicability. Remember, 100 Mb/s on SMF started as a separate call for
interest and was rolled into EFM for synergy.
The
EFM "environment" is not so different. It's the same frames, same rates,
same wavelength, same fiber type as "legacy" 1000BASE-LX and 10GBASE-L.
Same optional OAM proposed for all. Interoperable and interchangeable
PMDs. So why would the PCS be different?
I
don't believe that the proposed mandatory PHY changes are "particularly tuned"
even for the access market and I don't see your "less applicable - more
applicable" trade off. By demanding currently non-standard behavior
they go against Broad Market Potential, Compatibility and Economic Feasibility
even for the access market. They make it harder to connect a "legacy
Ethernet" data backbone network to a not-quite-Ethernet "EFM" access
network. Do NEMs have to make boxes where some long wavelength GBIC ports
have one PCS behavior and other long wavelength GBIC ports have the
opposite behavior? I suppose a service provider can go to ATM and back to
join the two!
Let's quote from the 100BASE-FX over dual Single Mode Fibre Call For
Interest of two years ago. Remember, as the web site http://www.ieee802.org/3/smfx_study/index.html
says,
The 100BASE-FX over dual Single Mode Fibre Call For Interest resulted in additional work being added to IEEE P802.3ah Ethernet in the First Mile task Force. From EFM minutes http://www.ieee802.org/3/efm/public/mar02/minutes_03_2002.pdf Additional Objective: p2p 100Mb/s on SM fiber Bruce T. presented a motion: To add an objective to the family of physical layer specifications 100Base-X >= 10 km over SM fiber ALL - for 105; Against 4; Abstained 22 802.3voters - for 59; Against 3; Abstained 9 Motion passed And from 802.3 minutes http://www.ieee802.org/3/minutes/mar02/minutes_0302.pdf :
802.3ah motion #1 Add an objective to the family of physical layer specifications: 100BASE-X >= 10 km over SM Fiber All Y:105 N: 4 A:22 .3 Y:59 N: 3 A: 9 Motion Passed And these quotations below (my emphasis) are from the
100 Mb/s over Dual SM Fiber 100 Mb/s over Dual SM Fiber Proposed PAR & 5 Criteria Proposed PAR & 5 Criteria http://www.ieee802.org/3/smfx_study/public/jonsson_1_0302.pdf Scope:
- Make amendment to Clause 26, 100BASE-FX, to include a 100Mbps dual SMF PMD Broad Market Potential Broad Market
Potential
... 100BASE-X SMF is main candidate for volume applications in: - Residential (FTTH) - Commercial (SME, Shopping malls, etc.) - Industrial (http://ethernet.industrial-networking.com) o Rapid growth anticipated in emerging areas - fiber to the radio base stations (FTTR) - fiber to WLAN HotSpots (FTTW) - fiber links connecting office desktops (FTTD) Compatibility
100BASE-X PCS & PMA assumed, and the 802.3
MAC
- No changes whatsoever to the MAC - PHY identical to current 100Mbps Std except for a new PMD - No change to Clause 24 - Retain all state machines, 4B/5B coding etc. of 100BASE-X o Only need to extend Clause 26, 100BASE-FX PMD, to include SMF o Physical medium compatibility through SMF - Compatible with existing 1000BASE-LX - Provides upgrade paths to higher speeds and multiple wavelengths, with fiber plant untouched - 100Mbps optical SMF components exist
- 'Pre-standard' links and systems already in commercial operation 100Mbps and EFM
o EFM deals with major additions to the 802.3 Std o 100BASE-X dual SMF only requires minimal additions to Clause 26 o 100BASE-X dual SMF is already happening, and will have applicability even outside EFM o However, 100BASE-X SMF will be used in the public access application space o 100BASE-X PCS is transparent to EFM OAM - Neither "OAM in Frames" nor "OAM on Preamble" require any changes to 100BASE-X PCS (Apologies to Ben
and anyone else who gets this message twice. Problems with the
filters.)
Piers
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