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.
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