RE: [EFM-P2MP] EPON efficiency white paper
Hello all,
About the delineation overhead part where it was calculated that only one grant in a cycle will be of wrong length compared to the length of offered packets. I got
different results based in assumption that the wrong length applies to all grants in a cycle:
If the cycle time is 1.5 ms and there
is 32 users who all get one slot each cycle, about 100
Mbit/s is lost out of 1 Gbit/s if each user looses 595
bytes each cycle. That is about 10%. If, on the other
hand, a user has an SLA of static 10 Mbit/s, that user
will actually get only 10 Mbit/s - 595 x 8 / 1.5 ms = 6.8
Mbit/s of bandwidth. Thus, that user looses 32%.
This calculation applies to the situation where the network is congested and the queues in ONUs are longer than can be granted. Of course, there is not much point in doing the calculation in other than congested situation.
There was an attempt to standardize a) an effective way for sending thresholds from OLT to ONUs and b) interpretation what the thresholds mean but it failed. In a network where ONUs and OLT are from different vendors, the traffic losses that I calculated are real. Is this pessimistic view right or wrong?
Antti
> -----Original Message-----
> From: ext Glen Kramer [mailto:glen.kramer@teknovus.com]
> Sent: 10 May, 2003 00:08
> To: stds-802-3-efm-p2mp@ieee.org
> Subject: [EFM-P2MP] EPON efficiency white paper
>
>
> Friends of EPON,
>
> There still exists a perception of inadequate efficiency of
> EPON. Many times I encountered inaccurate statements
> claiming the EPON efficiency to be extremely low.
>
> I attached a white paper explaining all the overhead
> components and justifying the values of configuration
> parameters. I tried to be as conservative as possible and
> considered all overhead components, even those with
> negligible values.
>
> Please, review it for accuracy and give me your comments.
> You may freely distribute this white paper.
>
> Thanks,
> Glen
>
> ---------------------------
> Glen Kramer
> Teknovus, Inc.
> glen.kramer@teknovus.com
> Office: (707)665.0400 x115
> Mobile: (530)306.5039
> ---------------------------
>
>
>