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RE: [EFM] (forward) progress in EFM copper

I agree on most of your points

--I like objectives.  I like many objectives for a single port.  I don't
like two ports for the same wire with the same connectors that cannot
speak to each other.  It is the same wire being used for both short and
long haul.  We get two port types because we have two lengths as
objectives on the same wire?  I want two objectives for the same port.

--I heard you say that market forces required all slower standards to be
included.  Why mix a passband modulation technology with a baseband
technology as you suggested?  The two technologies are unrelated in
implementation.  Why not select just QAM or dmt for both long and short
haul.  If you choose the same technology for both long and short haul
they interoperate freely. 

--dmt and QAM could do long and short haul and always allow POTS.  dmt
and QAM pack more bits per hertz when compared to shdsl.  I understand
doing both long haul and short haul in QAM is challenging.  Some tell me
that if we roll in interoperability between long and short haul as a
requirement, we will be making the coding decision.  Is this true?  

The question is: does the length of the wire make such a difference that
two distinct markets can be defined?

But why go to all trouble when it is so easy to make Ethernet work

I would like to see
--One coding technology for long and short haul
--The faster Phy always talks to the slower Phy at the slower rate
--I want my Ethernet to work when I plug it in.

Why is there an objection to an interoperability requirement between
long and short haul?  It is so easy with dmt it can be called a freebee.

Does an interoperability requirement select the line coding technology?

Daun Langston
-----Original Message-----
[] On Behalf Of O'Mahony,
Sent: Wednesday, June 12, 2002 10:00 AM
To: 'daun@xxxxxxxxxxxxxxxxxxxxxxxxx'; 'Hugh Barrass';
Subject: RE: [EFM] (forward) progress in EFM copper


--The optics folks have 5 or 6 objectives, don't they?  Having two
for copper is perhaps one for than some would like, but as a way to
consensus and move things forward it doesn't seem unprecedented.

--Ethernet does not ensure interoperability between different port
'never has.  Although in some cases, market forces drive putting more
one port type on a given device.  This is similar to the way the
was for voiceband modems, e.g., one could build a compliant V.34 modem
without including V.32bis, but for most applications, market forces
V.32bis and all slower standards to be included.

--This concept is being talked about as a "long reach objective" and a
"short reach objective", but I think the distinction is more than just
If you look at the presentations from Dong and other carrier
representatives, what we're really talking about are two disctinct
segments.  Technically, this comes down to an objective for loops that
require POTS overlay, and an objective for loops that don't.  This
the distinct identity requirement, I believe.  The objective for the
not requiring POTS overlay has a longer reach than the other one, so
referring to the two objectives as "short reach" and "long reach" is a
shorthand, that's all.


-----Original Message-----
From: Daun Langston [mailto:daun@xxxxxxxxxxxxxxxxxxxxxxxxx]
Sent: Wednesday, June 12, 2002 7:47 AM
To: 'Hugh Barrass';
Subject: RE: [EFM] (forward) progress in EFM copper

I strongly support this objective because it is reaches the distance I
have been pushing for at 2500 meters and the rate is 500 Kbit slower
than I have been asking for.  This is not hard to accomplish with the
same port type.

I do not support the intent for a separate port type to the PHY.  A
separate port type is not Ethernet.  By a separate port type you are
suggesting they would not interoperate.  Should we be the first copper
Phy in Ethernet that does not interoperate?  Let's try to make it the
same port type which suggests interoperability as some common rate.

Two identical connectors in the same marketplace called Ethernet that do
not interoperate at some basic speed is not really what folks now call
Ethernet.  Ethernet always works at some level.

Should we not try first to stick to the 802 rules?  I not just want to
see this pass 802.3ah but I also want to see this pass 802.3.

A single port type is very simple to accomplish.  Why don't we try this


Daun Langston
Metanoia Technologies, Inc.
127 Mill Street
Grass Valley, CA 95945
POB 1843 Nevada City, CA 95959-1843
daun@xxxxxxxxxxxxxxx (SMS)
+1 530 639-0311 office
+1 512 698-0311 cell
+1 530 671-0511 fax
+1 530 273-4093 design center

-----Original Message-----
[] On Behalf Of Hugh
Sent: Wednesday, June 12, 2002 1:19 AM
Subject: [EFM] (forward) progress in EFM copper


I have been considering the possibilities for progress on the copper
following the pointers that we got from the straw polls at the end of
the Edinburgh
interim. In particular I have been discussing a compromise with Dong Wei
of SBC
which would combine the short reach objective and VDSL baseline (which
achieved consensus) with a longer reach objective (and associated
baseline) to
satisfy the needs of service providers that Dong has articulated. As a
result of
this discussion we have formulated some ideas which we have also
discussed with
some other copperheads and have reached what I like to call:

"The Great Copper Compromise"

In essence this can be summarized as: leave the short reach objective
and VDSL
baseline unchanged; add a new objective for longer reach along with a
baseline solution that meets the objective.

Based on discussions that I've had with a number of copper track (and
other EFM)
members I think that this compromise could add the support for two
applications and get above the 75% threshold required for progress.
Clearly this
will only work if we can guarantee that everyone who has an interest in
solution votes positively for both. I cannot emphasize enough that we
aggregate all of the positive votes in Vancouver to keep the EFM effort
Many people believe that the copper component is vital to the whole of
EFM and that
no market will develop for the fiber (or OAM) components of EFM if there
is no
copper edge.

The objective that we have been discussing is:

PHY for single pair non-loaded voice grade copper distance >= 2.7km
speed >= 2Mbps
full duplex.

The intent is that this would be a separate port type to the PHY which
meets the
existing objective.

Dong Wei has agreed to lead the development of a presentation which
could be
adopted as a baseline meeting this objective. It is crucial that we get
support for this compromise, that means that we should attempt to
maximize the
number of people who review and support Dong's presentation. Please
could you all
consider working with Wei and adding your name as a supporter of his
I will arrange a conference call (probably June 24th) before the

With thanks for your attention,