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Re: [STDS-802-3-EPOC] [802.3_EPOC] Synchronization Eval Criteria for EPoC - Presentation for Jan. 8 Eval Criteria Ad Hoc Call



Bill, 

 

If I recall correctly, 802.3bf does not deal with time stamping, especially
not with MPCP time stamping. All it does it provides indication of passage
of packets through the xMII, which can be then correlated with transmission
of selected packets across PHY. That combined with information on PHY delay
stored in 802.3bf registers provides enough information to calculate precise
residence time for the station. 

 

So, I am confused what is really meant by "using a timestamping mechanism
for MPCP packets over EPoC similar to the method described in both 802.3bf
and 802.1as Clause 13". I think there is some misunderstanding as to what
802.3bf provides and misconception that it is a specification competitive to
802.1as (which it is not, it complements 802.1as as much as 1588v2). 

 

Marek

 

From: Bill Powell [mailto:bill.powell@xxxxxxxxxxxxxxxxxx] 
Sent: Tuesday, January 08, 2013 21:40
To: Marek Hajduczenia
Cc: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_EPOC] Synchronization Eval Criteria for EPoC -
Presentation for Jan. 8 Eval Criteria Ad Hoc Call

 

Marek,
Thanks for the review and comments.  I agree, we have not proven yet that we
can meet this criteria, especially the time transfer error criteria on slide
17.  However, due to industry requirements for MBH, and competing
technologies (GPON) that can provide even lower time transfer error
performance, I think we need to be aiming at architecting EPoC to try to
meet the goals in this presentation.  Having a goal in this area will help
us when we start comparing potential implementations.

Note that on Slide 17 the time transfer error performance is labeled as
tentative, which in my mind would depend on physical limitations of what we
do in the MAC<->PHY layer for EPoC.  

I agree that we will need to use a timestamping method for MPCP packets
described in 802.3bf.  I discussed the differences between 802.3bf and
802.1as (the protocol for MPCP counter synchronization between the EPON OLT
and EPON ONU) with Geoff Garner at our last meeting in San Antonio.  Geoff
mentioned that the timestamping method in 802.1as Clause 13 was essentially
similar to the MPCP timestamping criteria in 802.3bf, and the reason that
802.1as did not refer to 802.3bf directly is that 802.3bf was not completed
when 802.1as was balloted.  

So, the intent here is to propose using a timestamping mechanism for MPCP
packets over EPoC similar to the method described in both 802.3bf and
802.1as Clause 13.  I intentionally left off this level of
802.1as-vs-802.3bf detail in this presentation, as I thought it would not be
beneficial to the overall goal of:
(1) presenting a system level analysis relative to current MBH and CES
timing requirements, and 
(2) propose specific Eval criteria for EPoC to support these requirements.

Regards,
Bill

-------- Original Message -------- 


Subject: 

RE: [802.3_EPOC] Synchronization Eval Criteria for EPoC - Presentation for
Jan. 8 Eval Criteria Ad Hoc Call


Date: 

Tue, 8 Jan 2013 21:13:46 +0000


From: 

Marek Hajduczenia  <mailto:marek.hajduczenia@xxxxxx>
<marek.hajduczenia@xxxxxx>


To: 

'Bill Powell'  <mailto:bill.powell@xxxxxxxxxxxxxxxxxx>
<bill.powell@xxxxxxxxxxxxxxxxxx>,
<mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
<STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>

 

Bill, 
 
My two cents on that would be simple - a valuable contribution, but adopting
such requirements without even knowing if they are achievable, is at least
premature. We do not have any working models that would allow to estimate
whether such stringent requirements are achievable. 
 
Furthermore, despite multiple indications from my side, the support for IEEE
Std 802.3bf is being still ignored. Without it, I do not know how you can
even think of getting to the level of precision you're suggesting. The delay
through each layer in the EPoC PHY needs to be known if we can ever hope to
get 1588v2 to the precision level you're showing. 
 
Regards
 
Marek
 
-----Original Message-----
From: Bill Powell [mailto:bill.powell@xxxxxxxxxxxxxxxxxx] 
Sent: Tuesday, January 08, 2013 20:30
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: [802.3_EPOC] Synchronization Eval Criteria for EPoC - Presentation
for Jan. 8 Eval Criteria Ad Hoc Call
 
Hello All,
I've attached a presentation that I plan to present during the Eval Criteria
ad hoc call tomorrow (Jan. 9).  Some of you may have seen most of this
presentation in a different forum, but I'm bringing this into 802.3bn
through the Eval criteria Ad Hoc for further discussion, with a recommended
performance limit for time and frequency transfer error over the EPoC link
on Slide 17 (new slide).
 
If the group thinks that it would be useful to present to the whole 802.3bn
group, I can also submit it for presentation for the upcoming Phoenix or a
future 802.3bn meeting.
 
Regards,
Bill
 
-- 
 
Bill Powell
Alcatel-Lucent
Fixed Access Systems Engineering
2301 Sugar Bush Road
Raleigh, NC 27612
bill.powell@xxxxxxxxxxxxxxxxxx
(O)    919-850-6462
(Cell) 919-614-3225
 
 
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