RE: [EFM] Minutes of P2MP Optics conference 22nd Aug 20002
Roy:
Ethernet Framing add 5% (Slide 6)
FEC + Ethernet Framing adds 15% (Slide 7).
It is hard to calculate some of these independently. So we
know that RS(255,239) overhead is 7%. So the remaining
3% comes from F-FEC framing.
Ajay
> -----Original Message-----
> From: Roy Bynum [mailto:rabynum@xxxxxxxxxxxxxx]
> Sent: Friday, August 23, 2002 1:57 PM
> To: Ajay Gummalla; Thomas.Murphy@xxxxxxxxxxxx; gkramer@xxxxxxxxxxx;
> stds-802-3-efm@ieee.org
> Subject: RE: [EFM] Minutes of P2MP Optics conference 22nd Aug 20002
>
>
> Ajay,
>
> By your statement below, if I understood it correctly, the FEC adds about
> 15% overhead for the given distribution model. The last page of your
> presentation has 7% for FEC and 3% for Frame based FEC. Adding
> the FEC and
> Frame based FEC together, that is only 10% overhead.
>
> Also, I could not understand the bar chart that you had on page 10. Can
> you please reformat it so that the individual bandwidth components are
> stacked on top of each other to achieve the full line rate?
>
> Thank you,
> Roy Bynum
>
> At 01:37 PM 8/23/2002 -0400, Ajay Gummalla wrote:
> >Tom and Roy:
> >
> > The calculations are assumed a simple model and are
> >straighforward. I did assume equal distribution of bandwidth
> >to all ONUs and fully loaded system. This gives an idea
> >of where the asymptote of the delay vs throughput curve is.
> >To go much further than this, one had to do simulations
> >assuming a scheduler, request method and traffic model.
> >
> >Coming to the question of FEC, the numbers in this presentation
> >are correct. If you see slide 7, the efficiency for 64 byte
> >packets with FEC is 56% (64/(64+12+8+16)). But the overall
> >efficiency considering the particular packet distribution is 85%.
> >
> >I think people pretty much agree with the numbers.
> >
> >Ajay
> >
> > > -----Original Message-----
> > > From: Roy Bynum [mailto:rabynum@xxxxxxxxxxxxxx]
> > > Sent: Friday, August 23, 2002 1:24 PM
> > > To: Ajay Gummalla; Thomas.Murphy@xxxxxxxxxxxx; gkramer@xxxxxxxxxxx;
> > > stds-802-3-efm@ieee.org
> > > Subject: RE: [EFM] Minutes of P2MP Optics conference 22nd Aug 20002
> > >
> > >
> > > Ajay,
> > >
> > > If I am not mistaken, your presentation assumed equal full attempted
> > > utilization by all ONUs. Also, I thought that the FEC efficiency
> > > was much
> > > lower, the FEC overhead percentage was much higher,
> particularly for the
> > > smaller size frames.
> > >
> > > Thank you,
> > > Roy Bynum
> > >
> > >
> > > At 01:07 PM 8/23/2002 -0400, Ajay Gummalla wrote:
> > >
> > > >Tom:
> > > > I had made a presentation in the last EFM meeting addressing
> > > >exactly this issue. I broke down the overhead into its
> > > >components and did a performance analysis.
> > > >
> > > >You can find the presentation at the following URL:
> > >
> >http://www.ieee802.org/3/efm/public/jul02/p2mp/gummalla_p2mp_1_0702.pdf
> > > >
> > > >Hope this helps answer your questions.
> > > >
> > > >Ajay
> > > >
> > > > > -----Original Message-----
> > > > > From: owner-stds-802-3-efm@majordomo.ieee.org
> > > > > [mailto:owner-stds-802-3-efm@majordomo.ieee.org]On Behalf Of
> > > > > Thomas.Murphy@xxxxxxxxxxxx
> > > > > Sent: Friday, August 23, 2002 12:55 PM
> > > > > To: gkramer@xxxxxxxxxxx; Thomas.Murphy@xxxxxxxxxxxx;
> > > > > stds-802-3-efm@ieee.org
> > > > > Subject: AW: [EFM] Minutes of P2MP Optics conference 22nd
> Aug 20002
> > > > >
> > > > >
> > > > >
> > > > > Hi Glen,
> > > > >
> > > > > Thanks for the reply. Would it be possible to formulate
> > > > > the statements below into an Excel data-sheet which could then
> > > > > be used as a basis for discussion? I know that there has
> been some
> > > > > work in this direction and my hope is to generate one tool which
> > > > > has been accepted by the majority and can be used by all.
> > > > >
> > > > > Regards
> > > > >
> > > > > Tom
> > > > >
> > > > >
> > > > >
> > > > > -----Ursprüngliche Nachricht-----
> > > > > Von: Glen Kramer [mailto:gkramer@xxxxxxxxxxx]
> > > > > Gesendet am: Freitag, 23. August 2002 18:44
> > > > > An: Thomas.Murphy@infineon.com; stds-802-3-efm@ieee.org
> > > > > Betreff: RE: [EFM] Minutes of P2MP Optics conference 22nd
> Aug 20002
> > > > >
> > > > > Tom,
> > > > >
> > > > > This is to address action item #2 from the minutes.
> > > > >
> > > > > 2. Efficiency model based on guard bands and traffic type -
> > > P2MP group?
> > > > >
> > > > >
> > > > > There are 3 types of overhead (or bandwidth loss):
> > > > >
> > > > > 1. Cycle overhead. This is overhead used by guard bands
> > > (including CDR).
> > > > > It is measured as a number of guard bands in one cycle.
> This number at
> > > > > least equal to the number of ONUs, but may be even larger
> if we grant
> > > > > per LLID and there are multiple LLIDs per ONU.
> > > > >
> > > > > 2. Slot overhead. This overhead arises when granted slot
> > > does not take
> > > > > into account frame delineation in a buffer. Since frames cannot be
> > > > > fragmented, a frame that doesn't fit in the remainder of a
> > > slot will be
> > > > > deferred to next slot (in next cycle), leaving current slot
> > > > > underutilized.
> > > > >
> > > > > The size of unused slot remainder depends on frame size
> distribution.
> > > > > This distribution for today's traffic is known and there
> exist formula
> > > > > to calculate this unused remainder (for the case when
> > > assigned slot size
> > > > > has no correlation to the frame sizes).
> > > > >
> > > > > Few protocol proposals consider how to eliminate unused
> slot remainder
> > > > > completely, but it looks like it will require changes to the frame
> > > > > format. P2MP group is still debating about it.
> > > > >
> > > > > 3. Frame overhead. That includes IFG and headers.
> Nothing we can do
> > > > > about it.
> > > > >
> > > > > Glen
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: owner-stds-802-3-efm@majordomo.ieee.org
> > > > > [mailto:owner-stds-802-3-
> > > > > > efm@xxxxxxxxxxxxxxxxxx] On Behalf Of Thomas.Murphy@xxxxxxxxxxxx
> > > > > > Sent: Friday, August 23, 2002 1:57 AM
> > > > > > To: stds-802-3-efm@ieee.org
> > > > > > Subject: [EFM] Minutes of P2MP Optics conference 22nd Aug 20002
> > > > > >
> > > > > > Hello All,
> > > > > >
> > > > > > First off I apologise for sending this mail to the
> > > > > > EFM reflector, however, a number of issues arose which
> > > > > > are relevant for other groups.
> > > > > >
> > > > > > The next phone conference is planned for next Thursday
> > > > > > at the old time of 11:00 Eastern
> > > > > >
> > > > > > Regards
> > > > > >
> > > > > > Tom
> > > > > >
> > > > >
> > > > >
> > > > >
> > >
> > >
> > >
>
>
>