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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 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.


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 
> donít 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