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Re: [802.3_ISAAC] Comment on buffering difference between 802.3ch and TDD



Kirsten – not sure what existing parts you are referring to, but the basic protocol for EEE is asymmetric – it works independently in both directions.  LPI quiet/refresh is entered or exited from each direction by itself.  So, if the existing parts are built according to the standard, they would handle the asymmetry.

 

As to the 6 Gbps, case, this sounds like a case for a trade between power & area – you might save buffer and not go into quiet/refresh, or you might save power and use buffering.  Similarly to other phys when the rate doesn’t match if you have power saving modes…

 

George Zimmerman, Ph.D.

President & Principal

CME Consulting, Inc.

Experts in Advanced PHYsical Communications

george@xxxxxxxxxxxxxxxxxxxx

310-920-3860

 

From: Matheus Kirsten, EE-352 <Kirsten.Matheus@xxxxxx>
Sent: Wednesday, July 17, 2024 5:15 PM
To: STDS-802-3-ISAAC@xxxxxxxxxxxxxxxxx
Subject: [802.3_ISAAC] AW: Comment on buffering difference between 802.3ch and TDD

 

Hello Yunteng,

 

Yes, EEE can be done independently in UL and DL direction and you do not have to implement it on the camera side. However, how would you handle it if you only needed to transmit a camera video stream of 6 Gbps, while you have 10 Gbps link rate available. Would you want to use EEE to also safe power or rather send continuously filling the capacity with idle/alike?

 

Also, in many discussions I had, there was a desire to reuse existing parts. They would have EEE in both directions. However, if you make extra parts, it would be desirable to optimize. Of course.

 

Kind regards,

 

Kirsten

 

Von: Yunteng Huang <yunteng@xxxxxxxxxxxx>
Gesendet: Mittwoch, 17. Juli 2024 03:44
An: STDS-802-3-ISAAC@xxxxxxxxxxxxxxxxx
Betreff: [802.3_ISAAC] Comment on buffering difference between 802.3ch and TDD

 

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Dear Kirsten, Kamal,

Thank you for your contribution on buffering analysis:

https://www.ieee802.org/3/dm/public/0724/matheus_dalmia_dm_03_buffering_07152024.pdf 

 

In slide 12 of the presentation, you write that an FDX/EEE (802.3ch) would need “Normal MAC buffers (esp. pause), wake time buffers for min 9us @ high rate on the camera side. 

 

An implied assumption here is that 802.3ch based camera system would go in and out of LPI for power savings in the downstream direction analogous to TDD scheme.  In practice, frequent entering/exiting LPI is not needed in the downstream direction thanks to FDX.  If you leave the downstream direction active and only enter/exit LPI in the upstream direction, which is a rational use of EEE for this application, there would be no need for wake time buffers at high rate on the camera side. 

 

Sincerely,

Yunteng Huang


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