RE: [10GBASE-T] Power Down mode
Brad-
At 09:28 PM 8/6/2003 -0700, Booth, Bradley wrote:
Geoff,
I shall clarify my statement. A device which wishes to support
10M,
100M or 1000M may have to support half duplex.
True (per the "wishes of Marketing" as stated in my earlier
message)
As 802.3ae is currently
written and given our objectives, a device operating at 10G shall
set
half duplex capability to false, as per 4.2.7.5.
Also true
My interpretation of
Hugh's statement was that he was asserting that a 10G MAC has half
duplex capabilities.
I don't think (according to our current MAC standards model) that there
is any such thing as a 10G MAC, only a "universal" MAC
operating in 10G Mode.
The MAC running at this rate and using XGMII
or
XAUI is not capable of running in half duplex because of the
existing
shall statement in 4.2.7.5 and because neither XGMII nor XAUI have
carrier sense or collision detect signals.
This is an issue of the shortcomings of layers other than the MAC
My reply was built off an
implied assertion by Hugh about how EFM uses the half duplex
capabilities of the MAC to control the rate of data on the DSL
links.
My assertion was that a 10G MAC doesn't have that
capability.
See above.
It is becoming increasingly obvious though that our "single
MAC" is carrying too much baggage.
It needs some kind of help.
Geoff
If I misinterpreted Hugh's statement, then I'm
sure that Hugh will
correct me. My point was to make sure those familiar with the
EFM
method of rate control do not assume that method exists as 10G is
currently specified.
Thanks,
Brad
-----Original Message-----
From: Geoff Thompson
[mailto:gthompso@nortelnetworks.com]
Sent: Wednesday, August 06, 2003 6:50 PM
To: Booth, Bradley
Cc: stds-802-3-10gbt@ieee.org
Subject: RE: [10GBASE-T] Power Down mode
Brad-
Hugh is right, you are wrong.
His statement:
"One point though,
the MAC for 10GBASE-T may support HD if it
has
to work in 10/100/1000/10G autoneg mode..."
means that the MAC in back of a proposed transceiver IF
"10/100/1000/10G
autoneg" THEN the MAC would have to have appropriate switches to
operate
appropriately WHEN in either 10 or 100 (you can throw 1000 in too if
you
want). It would be a product marketing decision, not a standards
compliance
decision whether or not to support half duplex at those speeds.
The only requirement of the standard is that the autoneg adverti$ement
actually be accurate.
I know that you know all of this stuff as well as Hugh. It's fun to
joke
but, there are many others on this list who do not know the gruesome
details of the standard in detail. Let us not mislead them with our
misteaks.
Geoff
At 12:22 PM 8/6/2003 -0700, Booth, Bradley wrote:
>Hugh,
>
>Not if you comply with 4.2.7.5 in 802.3ae. :-) There is no
"may" in
>there as far as half duplex and 10G are concerned.
>
>Cheers,
>Brad
>
>-----Original Message-----
>From: Hugh Barrass
[mailto:hbarrass@cisco.com]
>Sent: Wednesday, August 06, 2003 2:14 PM
>To: Booth, Bradley
>Cc: stds-802-3-10gbt@ieee.org
>Subject: Re: [10GBASE-T] Power Down mode
>
>
>Brad,
>
>I was waiting for the fireworks to start :-)
>
>My tongue was in my cheek when I suggested half-duplex,
particularly
>seeing how unpopular it was for Gig. One point though, the MAC
for
>10GBASE-T may support HD if it has to work in 10/100/1000/10G
autoneg
>mode...
>
>Hugh.
>
>Booth, Bradley wrote:
>
> >Hugh,
> >
> >What is half duplex? :-) Seriously though, before all the
other
>802.3ae
> >and 10GbE experts jump on you, there is no half duplex in
10GbE. The
> >802.3ae MAC is full duplex only. Although EFM is using
half duplex
in
> >an interesting way to stall the MAC, we haven't seen anything
like
that
> >proposed for 10G.
> >
> >Let's see if we can get the PAR, 5 Criteria and Objectives
done
first,
> >then we can toy with other concepts to reduce power or data
rate.
> >
> >Thanks,
> >Brad
> >
> >-----Original Message-----
> >From: Hugh Barrass
[mailto:hbarrass@cisco.com]
> >Sent: Wednesday, August 06, 2003 12:27 PM
> >To: Fakterman, Boris
> >Cc: stds-802-3-10gbt@ieee.org
> >Subject: Re: [10GBASE-T] Power Down mode
> >
> >
> >
> >Boris,
> >
> >This would only really be useful for battery powered equipment.
Most
> >systems will be required to sustain maximum rate traffic
and
therefore
> >the idle periods will be less than 1% of the time.
> >
> >Another possibility is half-duplex. If the pre-coding and
pre-emphasis
> >is balanced well with the equalization & decoding then it
may be
> >possible to make a half-duplex transceiver consuming half the
power
of
>a
> >
> >full-duplex one. Of course there may be problems with
collision
radius
>&
> >
> >bursting, but this could enable some early implementations to
use HD
> >while the boffins are working on power reduction
techniques.
> >
> >Hugh.
> >
> >Fakterman, Boris wrote:
> >
> >
> >
> >>Hello all,
> >>
> >>Following the discussion regarding power, it looks like
there is a
> >>consensus that the 10Gb Phy dissipated power will be very
high at
> >>first silicon and relatively high at advanced future
versions.
> >>
> >>The average power is important for most problematic topics,
such as
> >>thermal conditions, power source availability and so
on.
> >>
> >>The average power can be reduced by using the Power-Down
mode. The
> >>transceiver does not transmit or receive data during
significant
> >>periods of time. Instead of transmitting idle symbols
while
consuming
> >>full power, the system can enter the Power-Down mode.
The
transmitter
> >>power can be reduced by stopping the transmission, the
receiver
power
> >>can be reduced as only minimal receive functions will be
active. The
> >>overall dissipated power during the Power-Done can be
reduced
> >>significantly.
> >>
> >>Of course there are algorithmic issues to solve, such as how
to
> >>maintain the synchronization during the Power-Down mode, but
these
are
> >>
> >>
> >
> >
> >
> >>technical problems that can be discussed and solved.
> >>
> >>The average power with implemented Power Down mode depends
on the
> >>length of idle periods.
> >>
> >>The desktop/laptop PC transmits idles most of the time (
> 90% ?). I
> >>don't know what happens in data centers.
> >>
> >>.If we can reduce even half of the dissipated power by the
Power
Down
> >>mode, it is worth to be considered.
> >>
> >>Regards,
> >>
> >>Boris Fakterman - Intel Communications Group, Israel
> >>
> >>Tel: 972-4-865-6470, Fax: 972-4-865-5999
> >>
>
>>mailto:boris.fakterman@intel.com
> >>
> >>
> >>
> >
> >
> >
> >
> >