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RE: [EFM] Changes to 100BASE-X and 1000BASE-X PCS, 10G RS

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 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
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 :
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
- 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 (
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)
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.)
-----Original Message-----
From: Benjamin Brown []
Sent: 01 March 2004 22:58
To: DAWE,PIERS (A-England,ex1)
Subject: Re: [EFM] Changes to 100BASE-X and 1000BASE-X PCS, 10G RS


That is an interesting perspective. Regardless of the PAR for this project,
we want to develop PHYs that can be used for all environments.

This is a project for the access network. The PHYs that come out of it
should be particularly tuned for that access market (and I believe they
are). If they can also be used for other markets then that's a bonus.
However, should we make these PHYs less applicable to the access
network just to make them more applicable to other networks when
the whole reason they exist is due to an access network project?

Ben wrote:


There is stuff in EFM that is just too good to be pigeon-holed into the relatively small and new "Ethernet for access networks" market. EFM has done good things which the large market of general IT/industrial/core/metro "legacy" Ethernets should be able and positively encouraged to take advantage of, within the 802.3 of the future, and with true compliance. 

In particular, the future 802.3 will allow a consistent physical infrastructure (fiber cable) that can be upgraded 100-fold from 100 Mb/s to 1 Gb/s to 10 Gb/s, with a consistent maximum reach of 10 km on SMF. That's so much better for network operators than having to revisit link lengths, cable types and attenuations whenever considering an upgrade. D3.1 Clause 66 presently tries to make this hard to do by asking for currently non-compliant PCSs. 

Even if the EFM group appears to be relaxed about this rules change for PCSs, 802.3 at large should not. The optics company doesn't forbid non-standard uses of its optics, but it does want the standard uses to be branded as standard so that IT departments everywhere can take advantage of our work without having the special knowledge needed to read between the lines. 

If you think the systems companies and users will do the right thing and carry on building ports with legacy PCSs and 100BASE-LX10, 100BASE-BX10 and 1000BASE-LX10 optics anyway, we end up at the same conclusion: the standard should say the right thing. Which has to be, treat 100BASE-LX10 the same as 100BASE-FX, treat 1000BASE-LX10 the same as 1000BASE-LX. 

This isn't just about names, it's about meeting objectives, recognising the good stuff, and the need for careful review of the PCS changes. Retrospective rules changes are not good. 


-----Original Message-----
From: Benjamin Brown []
Sent: 01 March 2004 16:25
To: DAWE,PIERS (A-England,ex1)
Subject: Re: [EFM] Changes to 100BASE-X and 1000BASE-X PCS, 10G RS


Your concern appears to be over the marketing of the 
GBIC/PMD-type devices.
100BASE-LX10, 100BASE-BX10 and 1000BASE-LX10 are all names of
PHYs, not optics. If an optics company can build optics that 
work in both a
1000BASE-LX PHY and a 1000BASE-LX10 PHY and they advert1$e the
optics as such, then they're not wrong if a system company 
misnames the PHY.
Today, common optics are built for multiple technologies (FC, 
It is not the concern of the optics company how their optics are used 
and what  name is applied to the port type.

The majority of the group appears to be comfortable with 
requiring the PCS to
be capable of unidirectional operation  in order to use the 
new EFM PHY names.
That doesn't mean system companies can't continue to build ports with 
or a limited set of capabilities. They just can't rightly 
call them by the new EFM  PHY names.

Ben wrote:
IEEE P802.3ah D3.1 proposes changes to:
	PCS and PMA sublayer, 100BASE-X.  See 66.1 and 24;
	PCS and autonegotiation, 1000BASE-X.  See 66.2 and 36 and 37;
	RS for 10Gb/s.  See 66.3 and 46.
and associated changes to management.

(There's also a great deal of new, good stuff which is in 
addition to the current 802.3, rather than having the effect 
of modifying it.)
The changes may have the unfortunate effect of changing some       
existing implementations to being non-compliant with 802.3.  
They might cause interoperability issues (need more reviewers 
to establish if they do or don't).

The well established practice of using 100BASE-X silicon 
with OC-3 like optics, called something like "Fast Ethernet 
on single mode fiber", which 802.3ah is meant to be 
standardizing under the name of 100BASE-LX10, now might fall 
foul of an effectively retrospective change, in which 
P802.3ah D3.1 says the PCS and PMA should support currently 
forbidden behavior.
The 100 Mb/s bidirectional link type, standardized as 
TS-1000 by TTC and as G.985 by ITU-T, uses the current 802.3 
PCS/PMA and a PMD compatible with 100BASE-BX10 - a PCS/PMA 
change would cause fragmentation and confusion.
P802.3ah has objectives:
	1000BASE-LX extended temperature range optics, and
	1000BASE-X up to 10km over SM fiber,
with the intention of bringing standardization with its 
associated benefits to the widely used "stretched 
1000BASE-LX" or 1000BASE-LH; the to-be-standardized PMD type 
being called 1000BASE-LX10.  But D3.1 says the PCS should 
support currently forbidden behavior for 1000BASE-LX10, while 
it says such behavior is to be optional for 1000BASE-LX or 
As 1000BASE-LX and 1000BASE-LX10 are interoperable by design, and
as a particular GBIC could be sold as compliant to 
1000BASE-LX or 1000BASE-LX10 while being identical, and
as pluggable optics means that any user can swap between 
1000BASE-LX, 1000BASE-LX10, 1000BASE-SX and even 1000BASE-T,
it is impracticable to demand different, unfamiliar, 
behaviour from the PCS, according to the paperwork associated 
with a probably pluggable, hot-swappable module.
It is not yet clear whether this causes an interoperability 
problem (need to understand how link starts up and reacts to 
faults with Cl.37 autonegotiation on just one end) but it IS 
clear that this is a market problem, making a retrospective 
change to 1000BASE-X PCS requirements and tending to fragment 
the market and/or weaken the validity of 802.3.
The modified 10G RS may cause interoperability problems 
interworking with current compliant 10G RS (I doubt this last 
one, but we need representatives from the 10G community to 
say yes, we have read this, understand the implications, and it's OK.)
At the last 802.3ah meeting we spent some hours 
investigating these issues, and learnt quite a lot of 
detailed points.  The committee was not willing to make 
significant changes to the draft at that time.  The problems 
remain, and the clock is ticking; we should get to the bottom 
of the issues, clean up the problems, and progress 802.3ah.
Therefore, I urge particular review of the subclauses 
mentioned above so that we don't go round in circles at the 
meeting, 15-18 March.  The comment deadline is midnight EST, 
Wednesday 3 March.
Thank you,

Piers Dawe
Benjamin Brown
178 Bear Hill Road
Chichester, NH 03258
603-491-0296 - Cell
603-798-4115 - Office
Benjamin Brown
178 Bear Hill Road
Chichester, NH 03258
603-491-0296 - Cell
603-798-4115 - Office