Hi all,
Rephrasing
Dave comment below,
If the objectives is only one pair then clause 33 cannot be supported
which I believe
is very limiting the scope of applications and the possibility to
expand
in the future to support clause 33.
I would
suggest that the group
initial objective may be to support two pairs, (data can be on one or
two
pairs) however the 2nd pair will be available for power
delivery per
clause 33. We can always reduce to single pair later if we will see
that it
cause issues.
Yair
Hi George,
Including objectives for Clause 28 and Clause 33 (even optional) would
restrict
the Study Group to at least 2 twisted pairs. If the study group is
still
considering only one pair we cannot include these objectives.
Thanks,
Dave
On 6/26/2012 1:02 PM, George Zimmerman wrote:
Seeing Brad’s note about the energy efficiency
discussion reminded me that one of the reasons to consider not
necessarily
going directly with 802.3az at the face-to-face was that it would be
desirable
to use the network as a control network, and hence, packet latency
would be an
issue.
This got me thinking, should we have a latency
objective?
Signal processing latency is probably not a PHY
problem for
normal modes, but could influence coding strategies for dealing with an
impulsive EMC environment, and, would likely influence any transitions
out of
low-power states for energy efficiency.
It would be good to get the group’s minds
thinking
about what fundamental parameters we may have left out (of the kind
that are
specified in interface standards – e.g., not absolute power or
complexity, but yes to reduced power modes, latency, speed, distance,
media,
duplexing, compatibility with environment & other signals,
autonegotiation,
etc.)
Here’s my list of what I think we’ve covered
thus far:
Speed (fixed
in the CFI
– 1000Mb/s at MAC/PLS interface wording to be approved)
Media (fixed
in the CFI
– twisted pair copper, wording to be worked)
802.3 framing
(agreed)
802.3 frame
sizes (agreed)
Distance
and/or channel
loss, (still working the exact language)
Topology (3
connectors
proposed, – to be approved)
EMC (still
working the
language)
BER
performance (prelim
agreed)
Training time
from cold
start (needs work and agreement, still)
Optional
energy efficient
operations (proposed – to be approved at this general level, may need
further definition)
Questions on other issues that that have been
raised, which,
depending on the resolution, may be objectives:
Do we support
clause 28
(or other) autonegotiation, even optionally?
Support or
even
compatibility with Clause 33 DTE Power over MDI (existing poe)?
Minimum
latency (normal
and especially for transitions out of low power mode)
-george
George
Zimmerman
Principal,
CME Consulting
Experts in Advanced PHYsical Communications
Technology
310-920-3860