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Re: [802.3_10SPE] Objectives - things we seem to have consensus on



I think the difficulty in separating the 15 PHY objective into two objectives is that it isn't clear that it will be two PHYs. It is possible that the same PHY would be used for both point to point and P2MP/bus.

We have had groups in the past with an objective to consider including a feature in their standard - i.e. at the time we started the project, we felt more work was needed to decide whether to include that feature; that the feature was a nice to have but not a requirement.

One way of making that explicit would be to have objective 9 be:
Define the performance characteristics of a link segment and at least one PHY to support point-to-point operation and possibly shared media operation over this link segment with single twisted pair supporting up to four inline connectors using balanced cabling for at least 15 m reach

and have an objective 
Consider support for shared media operation at distances up to 15 m.

Pat

On Fri, Oct 28, 2016 at 12:59 PM, Geoff Thompson <thompson@xxxxxxxx> wrote:
George-

My thought was based on the belief that multi-hop and/or P2MP are a very different beast 
from P2P
and thus should have distinctly different objectives.

Geoff

On Oct 28, 2016, at 12:54 PMPDT, George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx> wrote:

There are two reasons, because there are two wording differences:
-          “at least one phy” (15m) vs. “a phy”(1 km):  I don’t want to preclude the 1km phy from working on the 15m link segment, and want to make it clear we could end up with 2 phys that work on the 15m segment, but only one for the 1km link segment.
-          Omitting “point-to-point” on the 15m – While I believe we have consensus that the 1km link is not multi-drop, at this point we have had much discussion and reason to believe that a multi-drop 15m phy would be useful as well as meet the BMP and Economic feasibility CSDs.  Our CSDs and PAR as written do not preclude this.  We need work to specify the multi-drop scenario, and, I believe that requires technical decisions that are beyond the scope of what a study group should be doing (e.g., choosing media access approach).
I could live with the addition of “point-to-point” on the 15m link, but wanted to start general – let’s see what the consensus in the study group is.   
 
My personal belief is that at this point in the objective we can be general, and make room for an additional objective for multi-drop (not multi-hop, which would involve phy termination) links should it be proven out with technical decisions, perhaps refining the wording of this objective at that time.
 
Perhaps you could explain why it would be an error to leave the objective general? (or is it not an error, but a malformed piece of beef? (a ‘misteak’)
 
(FYI, I’m going to be offline now for a while…  don’t read anything into my silence)
 
Thanks for jumping in, Jeff.
-george
 
From: Geoff Thompson [mailto:thompson@xxxxxxxx] 
Sent: Friday, October 28, 2016 12:44 PM
To: George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>
Cc: Geoff Thompson <thompson@xxxxxxxx>; STDS-802-3-10SPE@LISTSERV.IEEE.ORG
Subject: Re: [802.3_10SPE] Objectives - things we seem to have consensus on
 
George-
 
Why is your wording on your draft 9 and 10 different?
If is because you want to leave things open for multi-hop
I believe that would be a misteak.
Point-to-point links should have separate statements from multi-hop links.
 
Regards,
 
            Geoff
 
 
On Oct 28, 2016, at 11:43 AMPDT, George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx> wrote:
 
I’ve been preparing a presentation to close our objectives, and from the ad hoc discussion, we seem to have consensus on the following objectives. (another few email threads will discuss the ones we need to work).
Please reply whether you have issues with consensus on these, and with some explanation of the concern, or proposed alternative wording.  Please reference the number of the objective in your comment.  These are NOT intended to be all the objectives, just the ones that I have heard general consensus on in the ad hoc.  This way we can have a more efficient meeting in San Antonio.
(the adopted objectives are #1 through 8)
 
  1. Define the performance characteristics of a link segment and at least one PHY to support operation over this link segment with single twisted pair supporting up to four inline connectors using balanced cabling for at least 15 m reach.
  2. Define the performance characteristics of a link segment and a PHY to support point-to-point operation over this link segment with single twisted pair supporting up to 10 inline connectors using balanced cabling for at least 1 km reach
  3. Do not preclude working within an Intrinsically Safe device and system as defined in IEC 60079
  4. Do not preclude the ability to survive automotive and industrial fault conditions (e.g. shorts, over voltage, EMC, ISO16750).
  5. Support fast-startup operation using predetermined configurations which enables the time from power_on**=FALSE to a state capable of transmitting and receiving valid data to be less than 100ms.
  6. Support voltage and current levels for the automotive and industrial environments.
 
 
 
George Zimmerman, Ph.D.
10 Mb/s Single Twisted Pair Ethernet Study Group
President & Principal
CME Consulting, Inc.
Experts in Advanced PHYsical Communications