Re: [STDS-802-3-EPOC] Evaluation Criteria and Requirements Ad Hoc Minutes
Thank you Geoff,
I think you?re referring to timing requirements, namely the maximum delay
through PHY (or individual sublayers, e.g., PCS, RS, MPMC) that we specify
for individual PHY types. I believe there is no doubt that we do specify
such delay requirements in 802.3 (in fact, we have them in EPON as well, as
far as I could trace for PCS, and MPMC defined separately).
What I do not think we have specified until now for any PHY (P2P or P2MP) is
the tolerance for timing and synchronization transfer through the given PHY.
Timing and synchronization in this case is a service supported by the PHY,
but controlled by the upper layers. In simpler terms, what this would be
asking us to specify the precision we guarantee for the transfer of IEEE
1588v2 packets across EPoC PHY. It is, I think, a novel type of requirement,
though it is not only a PHY issue, but also affects MAC Client layers. Any
value we could specify therefore (e.g. 150 ns of tolerance) would affect
802.3 and 802.1 layers together (as well as many things outside the scope of
802 in general), since it is a service layer requirement.
Regards
Marek Hajduczenia, PhD
ZTE Portugal
Technology Strategy Department
Edifício Amoreiras Plaza,
Rua Carlos Alberto da Mota Pinto, nr. 9 - 6 A,
1070-374 Lisbon, Portugal
Office: +351 213 700 090
Fax: + 351 213 813 349
Mobile: +351 961 121 851 (Portugal)
From: Geoff Thompson [mailto:thompson@xxxxxxxx]
Sent: Wednesday, 16 January, 2013 10:47 PM
To: Marek Hajduczenia
Cc: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-3-EPOC] Evaluation Criteria and Requirements Ad Hoc
Minutes
Marek-
Just a historical note...
Such timing specifications were common for PHYs when 802.3 was specifying
PHYs for CSMA/CD systems.
Round trip delay was a crucial parameter in determining the diameter of a
CSMA/CD network.
The numbers used for the initial work in that area can be found in Annex B
of 802.3.
It was only when we went to full duplex systems that this type of material
fell into disuse.
(CSMA/CD is, of course, just an access arbitration method for TDD)
Best regards,
Geoff
On 161//13 12:14 PM, Marek Hajduczenia wrote:
Duane,
First it would need to demonstrated that such a symmetry can be achieved
with such a tight tolerance (I cannot even think or where to start to
guarantee something like that), and only then draw conclusions on what the
synchronization / frequency tolerance should be. Putting requirements into
our project which are either system level requirements or have no evaluation
as to their impact on the complexity / cost / performance of what we are
trying to do, is just asking for trouble.
Let?s not put the cart before the horse.
Marek
From: Duane Remein [mailto:Duane.Remein@xxxxxxxxxx]
Sent: Wednesday, 16 January, 2013 08:03 PM
To: Marek Hajduczenia; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Cc: Duane Remein
Subject: RE: [STDS-802-3-EPOC] Evaluation Criteria and Requirements Ad Hoc
Minutes
Marek,
I agree with you that this is a system level specification. But I think we
need to develop PHY level specifications that ensure a system can meet this
level of synchronization. I don?t think this will be much beyond adding a
requirement that EPoC US path and DS path within a PHY have a symmetrical
delay within some bounds (such as ± 1 or 2 TQ ). While it is true that we
didn?t do this for EPON we may have gotten lucky. If it is relatively easy
to accomplish I think such a requirement is in order.
Best Regards,
Duane
FutureWei Technologies Inc.
duane.remein@xxxxxxxxxx
Director, Access R&D
919 418 4741
Raleigh, NC
From: Marek Hajduczenia [mailto:marek.hajduczenia@xxxxxx]
Sent: Wednesday, January 16, 2013 12:15 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-3-EPOC] Evaluation Criteria and Requirements Ad Hoc
Minutes
Steve,
I?d like to request that the minutes reflect concerns Leo and I brought
forward in relation to the frequency and synchronization precision
requirements. We believe these are not PHY specific requirements, but system
level requirements. If such a requirement does find its way into PHY spec,
there is no way to verify it separately, i.e., nobody measures what part of
the system level precision budget is consumed in PHY alone.
I?d also like to have it recorded in the minutes (as mentioned on the call)
that EPON does support mobile backhaul services with *no* requirements of
this type thrown into the PHY specs.
Furthermore, I believe it was also mentioned that such a requirement would
overly burden devices that are not expected to carry mobile backhaul
services. However, in the PHY spec it is not possible to distinguish one
from another (there is just a PHY), given that 802.3 does not provide
product specs. Such system level requirements should be brought forward to
the group that deals with a system level design.
Regards
Marek
From: Shellhammer, Steve [mailto:sshellha@xxxxxxxxxxxxxxxx]
Sent: Wednesday, 16 January, 2013 05:04 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-3-EPOC] Evaluation Criteria and Requirements Ad Hoc
Minutes
All,
Attached are the minutes for the Evaluation Criteria and
Requirements Ad Hoc meeting this morning, and also the latest open issues
list.
Steve
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