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Re: [EFM-P2MP] FW: [EFM] EFM FEC Proposals





The meeting minutes from Edinburgh, specifically
motion #17, on pages 7 and 8, give us a lot of help.

http://www.ieee802.org/3/efm/public/jul02/minutes_1_0502.pdf

 From this, I see that a very strong preference has been expressed
for an FEC option that works with both P2P and P2MP, while
maintaining backward compatibility with the 1000BASE-X PCS.

We will discuss this subject in Vancouver.
Both of the FEC proposals that have been submitted are in order.
The Task Force must make a decision on which proposal to adopt.

Howard Frazier
Chair, IEEE 802.3ah EFM Task Force

Mccammon, Kent G. wrote:

>Larry,
>Did we take a direction for a FEC solution for both P2P and P2MP? If so, we
>probably are looking for a single FEC method for both.  I would like FEC
>that operates well for P2MP to help meet the 20 km objective for P2MP.  If
>the same method for FEC works for P2P as well, that is a bonus advantage.  I
>am not willing to be tied to picking the best FEC for P2P that solves all
>the backwards compatibility issues if it is not the best method for P2MP.
>When comparing the different methods on the table I would propose to split
>the issue between P2P and P2MP in the comparison table.
>
>I look forward to those discussions, I wanted to air that thought in
>advance.
>-Regards, Kent
>
>>-----Original Message-----
>>From: larry rennie [mailto:Larry.Rennie@xxxxxxx] 
>>Sent: Wednesday, July 03, 2002 4:20 PM
>>To: Ajay Gummalla
>>Cc: stds-802-3-efm-p2mp@xxxxxxxxxxxxxxxxxx; 
>>stds-802-3-efm@xxxxxxxxxxxxxxxxxx
>>Subject: Re: [EFM-P2MP] FW: [EFM] EFM FEC Proposals
>>
>>
>>
>>Ajay,
>>
>>Thanks for the comparison slide.  I have the following comments.
>>
>>1. On the Protection column you say that the S-FEC provides 
>>equal protection of all bits. This is not quite accurate 
>>since the CW synchronization bit pattern needed by both the 
>>S-FEC and F-FEC proposals is not, and cannot be, protected by 
>>the code.  The F-FEC CW sync pattern happens to also contain 
>>the Ethernet start of frame word so it does double duty as 
>>both  CW sync and frame sync for an FEC enabled receive node 
>>and a frame sync for a non-FEC (legacy) receive node. I do 
>>agree that the S-FEC has more freedom to come up with a 
>>reliable tbd sync pattern , on the other hand, the F-FEC 
>>proposal describes a sync pattern and pattern detection 
>>method using correlators that seems fairly robust.
>>
>>2. On the Prior field experience column,  I think that what 
>>is proven by G.975 is the performance of the RS(255,239) code 
>>in an optical link.  Since both the S-FEC and F-FEC use the 
>>RS(255,239) code then you could say, to this extent, that 
>>both proposed methods are "field proven".  I agree that the 
>>ability of the F-FEC to operate with both FEC enabled and 
>>non-FEC enabled nodes is not field proven, but that's where 
>>our job comes in ,i.e., to specify the design so that it will 
>>operate in the field.
>>
>>I'm glad were getting these issues aired and discussed before 
>>the meeting.
>>
>>See you in Vancouver?
>>
>>Regards,
>>
>>Larry
>>
>>Ajay Gummalla wrote:
>>
>>>Larry and all:
>>>   I have attached a slide which compares the two proposals. I am 
>>>hoping that this will generate more discussions and help us make 
>>>progress.
>>>
>>>Please take a look at 
>>>
>>http://www.ieee802.org/3/efm/public/jul02/p2mp/gummalla_p2mp_1_0702.pd
>>
>>>f
>>>for the calculations on efficiency.
>>>
>>>Best Regards,
>>>Ajay
>>>
>>>>-----Original Message-----
>>>>From: owner-stds-802-3-efm@majordomo.ieee.org
>>>>[mailto:owner-stds-802-3-efm@majordomo.ieee.org]On Behalf 
>>>>
>>Of larry 
>>
>>>>rennie
>>>>Sent: Monday, July 01, 2002 6:31 PM
>>>>To: stds-802-3-efm
>>>>Subject: [EFM] EFM FEC Proposals
>>>>
>>>>
>>>>
>>>>Fellow EFM Task Force Members,
>>>>
>>>>At the last EFM meeting in Edinburgh we passed the following FEC 
>>>>motion:
>>>>
>>>>17. Motion to add an FEC option for the 1Gig P2P and P2MP PHY, 
>>>>maintaining backward compatibility with the 1000BASE-X 
>>>>
>>PCS, for the 
>>
>>>>following reasons:
>>>>    1. Improves reach of a MPN limited link by 50% for links with 
>>>>MPN penalty of about 2dB
>>>>    2. Permits operation at a SNR lower by 2.5 dB for 
>>>>
>>non-dispersion 
>>
>>>>limited links.
>>>>
>>>>Two different FEC implementation proposals will be presented in 
>>>>Vancouver and they are posted under the General Session 
>>>>
>>material on 
>>
>>>>the EFM web site.  One proposal is frame based and the other is 
>>>>stream based.  If you are at all interested in FEC for EFM, I 
>>>>encourage you to please take a look at these two 
>>>>
>>proposals and get 
>>
>>>>your comments and questions back onto the reflector before the 
>>>>meeting.  This will give the presenters and their 
>>>>
>>supporters time to 
>>
>>>>formulate a proper response and will conserve our 
>>>>
>>precious meeting 
>>
>>>>time in Vancouver.
>>>>
>>>>Regards,
>>>>
>>>>Larry
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>  
>>>
>>--------------------------------------------------------------
>>----------
>>
>>>                                      Name: Comparison of 
>>>
>>FEC proposals.pdf
>>
>>>   Comparison of FEC proposals.pdf    Type: Portable 
>>>
>>Document Format (application/pdf)
>>
>>>                                  Encoding: base64
>>>
>>
>
>