RE: [EFM] FEC needs a good discussion home!

["Mccammon, Kent G." <kmccammon@tri.sbc.com>]

Title: Message

Frank and Larry,

SBC continues to push for greater reach and greater power budget as they both help to reduce the cost of deployment in terms of the fiber infrastructure required to support EPON.  Thus, SBC encourages working towards FEC. From the presentations  using FP lasers at the ONT appears to be possible with  manageable probability of link failure with the help at FEC for the longer reach objective of 20 km.  

-Kent

 

-----Original Message-----
From: FEffenberger@quantumbridge.com [mailto:FEffenberger@quantumbridge.com]
Sent: Wednesday, May 08, 2002 10:46 AM
To: Larry.Rennie@nsc.com; stds-802-3-efm@ieee.org
Subject: RE: [EFM] FEC needs a good discussion home!

Larry,

 

First of all, I am a supporter of FEC, and think that we should continue working on it.

 

However, I would not favor moving the FEC topic out of the optics track.  The primary

application of FEC is to make up for shortcomings in the optics.  Therefore, where better

to discuss it than the optics track?  There is no doubt that FEC will be located inside

the PHY layer, and not in the MAC layers (it is unfeasible, otherwise).  Hence, the optics

track is where it belongs. 

 

Regarding the priority of FEC inside the optics track... regrettably, there are some very

important issues that have yet to be solved (the P2P wavelength choice being the most

obvious one).  While these other issues rank higher than FEC, I, for one, do not believe

that that will rule out the inclusion of FEC in the standard, pending a full examination of

the evidence.  I'm sure that Vipul would agree with this basic approach. 

 

The task force chair is occasionally emphatic at times about "baseline now!" and

"minimum number of PHYs!", but I do not believe it is the chair's intention to throw out 

valid topics of consideration purely on the grounds that it doesn't fit his schedule.  

The IEEE process has no pre-ordained schedule.  If it takes an extra meeting, 

then so be it.  

 

On the actual work, what I've seen is that there have been two proposals regarding the

application of FEC.  I authored one, and Lior from Passave authored the other.  On their

face, they both use the same base code, RS(255,239,8), and promise the same sort

of performance boost.  The differences between these two systems has to do with how

to protect the framing control codes, and how to insert the parity symbols.  I have

been looking forward to a conversation regarding these issues, but to date nobody

has offered to organize such a thing.  We should start this soon, with the goal of reaching

a more coherent picture by mid-summer. 

 

Sincerely,

Frank Effenberger.

 

 

-----Original Message-----
From: larry rennie [mailto:Larry.Rennie@nsc.com]
Sent: Wednesday, May 08, 2002 1:04 PM
To: stds
Subject: [EFM] FEC needs a good discussion home!

FEC needs a good home with EFM for discussion purposes.  Right now FEC is being discussed in the optics track but it has the least priority.  Is this still the correct track ?   As has been presented in several previous  presentations, FEC can reasonably be added just after the GMII interface. Therefore, it is a valid consideration for discussion issue within the EFM TF.  As some have said, "if the payload warrants FEC let the upper layers decide on whether or not to include FEC".  I don't believe this is the correct  way to treat FEC for EFM.  The addition of FEC can bring substantial benefits to our EFM standard.   These have been discussed in prior presentations (increased range, link quality monitoring, relaxation of BER spec for PMD, etc.).

Regards,

Larry