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Re: [802.3_NGAUTO] Comments on Mike Tu's Presentation "Converging on Framing and Training - August 22, 2018"

Hi Paul,

In my FEC proposal, the baseline RS parameter is N=720, K=650, and m=10 bit/symbol. It consists of 100 64B/65B PCS blocks. The extra one data symbol is reserved for OAM.

Conceptually, the overhead bits are added in the following manner:

PCS input: 64 bit
PCS output: 65 bits

100 PCS blocks = 6500 bits
1 OAM symbol = 10 bits

FEC input: 6510 bits = 651 symbols
FEC output: 7200 bits = 720 symbols

Overall input/output ratio = 6400 / 7200 = 8/9.

Hope this clarifies your question. Or please let me know if you have further questions. Thank you.

On Wed, Aug 22, 2018 at 9:06 AM Paul Langner <Paul.Langner@xxxxxxxxxxxx> wrote:

I apologize, I tried to comment during the meeting but my audio was not working.

 

Regarding Mike Tu's presentation - the choice of PCS, FEC, and baud rate are all tied together and cannot be independently chosen.  For instance you should have an integral number of PCS frames in the FEC frame, and of the proposals listed, 65 does not divide evenly into any of the FECs.  Consider Clause 134 which uses RS1024 (544,514) - 514 x 10 is a multiple of 257, and the rate multiplier is 5440/5120 = 17/16.  So we need to pick the FEC and the PCS together given the rate ratio of 9/8 instead of independently.

 

Regards,

 

Paul Langner

Aquantia Corporation

 

 

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