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RE: [EFM] PON timing parameters


You are right to say that the efficiency difference between the
remaining two choices is small, so why not go with the looser spec
(laser on/off at the ONU).  But it is my understanding that even with
the looser spec, the transceiver laser on/off driver needs to be
modified, so in that case it might as well be modified to 16 nsec
on/off.  What the modified C has going for it is:

(a) the laser on/off spec is available from several vendors today
(technically feasible)
(b) NO ONU parameter negotiation during discovery
(c) it avoids multiple "flavors" of ONUs (this is key) 
(d) OLT does not need to keep track of ONU parameter table
(e) it matches ITU-T specs at the ONU

I think Option C (as modified) is, as Frank says, a practical
compromise.  It seems to hit the sweet spot between those looking at
settable parameters, and those looking at fixed tight parameters.  It
gives flexibility at the OLT, and fixes the ONT values.  I'm looking
forward to the call next week to hear from Meir, Tom, Ketan, etc .. as I
am picking up a lot from their comments.  Personally, I like to try to
see this driven to consensus before Vancouver.  What the B supporters
need to prove now is that a 600 nsec ONU is less expensive than a 16
nsec ONU.   If that can't be shown, there are no remaining roadblocks to
the modified Option C in my opinion.  

Happy holidays to you. 


> -----Original Message-----
> From: Lior Khermosh [mailto:lior.khermosh@xxxxxxxxxxx]
> Sent: Friday, December 13, 2002 7:57 AM
> To: Gerry Pesavento; FEffenberger@xxxxxxxxxxxxxxxxx;
> Subject: RE: [EFM] PON timing parameters
> Gerry,
> A valid conclusion from your excel sheet could also be:
> use option B (even without negotiation)!
> After all the difference in efficiency is only 1.9%.
> 5.7%-3.8%=1.9%
> Lior Khermosh
> Passave
> -----Original Message-----
> From:
> []On Behalf Of Gerry
> Pesavento
> Sent: Thursday, December 12, 2002 11:07 PM
> To: FEffenberger@xxxxxxxxxxxxxxxxx; Vipul_Bhatt@xxxxxxxx;
> Subject: RE: [EFM] PON timing parameters
> Attached is the timing parameter table, that is the result of the PMD
> conference call this morning.  As you can see, there has been
> significant progress, and two Options are currently on the table.  The
> OLT parameters are identical.  The remaining decision concerns the ONT
> laser on/off time (make large and settable, or make small and fixed).
> Fixed parameters in ONTs (option C) are attractive since it will not
> require the OLT to keep a table with on/off times per ONT. Settable
> parameters per OLT are almost mandatory (CDR time is different with
> without FEC, protocol delay may not be constant, etc).  As Frank
> mentioned, settable parameters means that during initialization the
> will broadcast a value that represents a number of idles that ONT
> transmit at the beginning of the burst.  This seems to be a simple and
> robust approach.
> Glen/Gerry