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
>>>
>>
>
>