RE: [10GBASE-T] Power Down mode
I shall clarify my statement. A device which wishes to support 10M,
100M or 1000M may have to support half duplex. As 802.3ae is currently
written and given our objectives, a device operating at 10G shall set
half duplex capability to false, as per 220.127.116.11. My interpretation of
Hugh's statement was that he was asserting that a 10G MAC has half
duplex capabilities. 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 18.104.22.168 and because neither XGMII nor XAUI have
carrier sense or collision detect signals. 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.
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
From: Geoff Thompson [mailto:firstname.lastname@example.org]
Sent: Wednesday, August 06, 2003 6:50 PM
To: Booth, Bradley
Subject: RE: [10GBASE-T] Power Down mode
Hugh is right, you are wrong.
"One point though, the MAC for 10GBASE-T may support HD if it
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
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
At 12:22 PM 8/6/2003 -0700, Booth, Bradley wrote:
>Not if you comply with 22.214.171.124 in 802.3ae. :-) There is no "may" in
>there as far as half duplex and 10G are concerned.
>From: Hugh Barrass [mailto:email@example.com]
>Sent: Wednesday, August 06, 2003 2:14 PM
>To: Booth, Bradley
>Subject: Re: [10GBASE-T] Power Down mode
>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
>Booth, Bradley wrote:
> >What is half duplex? :-) Seriously though, before all the other
> >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
> >an interesting way to stall the MAC, we haven't seen anything like
> >proposed for 10G.
> >Let's see if we can get the PAR, 5 Criteria and Objectives done
> >then we can toy with other concepts to reduce power or data rate.
> >-----Original Message-----
> >From: Hugh Barrass [mailto:firstname.lastname@example.org]
> >Sent: Wednesday, August 06, 2003 12:27 PM
> >To: Fakterman, Boris
> >Cc: email@example.com
> >Subject: Re: [10GBASE-T] Power Down mode
> >This would only really be useful for battery powered equipment. Most
> >systems will be required to sustain maximum rate traffic and
> >the idle periods will be less than 1% of the time.
> >Another possibility is half-duplex. If the pre-coding and
> >is balanced well with the equalization & decoding then it may be
> >possible to make a half-duplex transceiver consuming half the power
> >full-duplex one. Of course there may be problems with collision
> >bursting, but this could enable some early implementations to use HD
> >while the boffins are working on power reduction techniques.
> >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
> >>full power, the system can enter the Power-Down mode. The
> >>power can be reduced by stopping the transmission, the receiver
> >>can be reduced as only minimal receive functions will be active. The
> >>overall dissipated power during the Power-Done can be reduced
> >>Of course there are algorithmic issues to solve, such as how to
> >>maintain the synchronization during the Power-Down mode, but these
> >>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
> >>mode, it is worth to be considered.
> >>Boris Fakterman - Intel Communications Group, Israel
> >>Tel: 972-4-865-6470, Fax: 972-4-865-5999