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@mindspring.com]
> > Sent: Friday, August 23, 2002 1:24 PM
> > To: Ajay Gummalla; Thomas.Murphy@infineon.com; gkramer@ucdavis.edu;
> > 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@infineon.com
> > > > Sent: Friday, August 23, 2002 12:55 PM
> > > > To: gkramer@ucdavis.edu; Thomas.Murphy@infineon.com;
> > > > 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@ucdavis.edu]
> > > > 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@majordomo.ieee.org] On Behalf Of Thomas.Murphy@infineon.com
> > > > > 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
> > > > >
> > > >
> > > >
> > > >
> >
> >
> >