Re: [802.3_DIALOG] Removing error ratio requirements from Std 802

[George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>]

Looks like the 802rev webpage misled me. (https://www.ieee802.org/1/pages/802-rev.html )
It points to a rev as the latest - which turns out is from 2010.  In that one it is 5.3...  the content is the same though, and is now 6.2 in 802-2014 as you point out.
(somewhere along the way they added new content which changed the numbering)

You're right, the wireless folks don't like this because it makes wireless links look inferior.  However, the requirements I see do not apply to them, unless they've changed that in the revision draft.  In 802-2014 are only for wired & optical, for wireless it says basically the media can't be trusted: "For wireless physical media, the error performance within a single access domain is variable over time, and no guarantee of service can be given."

-george


-----Original Message-----
From: ROBERT GROW <bobgrow@xxxxxxx> 
Sent: Tuesday, May 2, 2023 11:32 AM
To: George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>
Cc: STDS-802-3-DIALOG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_DIALOG] Removing error ratio requirements from Std 802

George, 

I’m slightly confused by you citing subclause 5.3.  The topic is subclause 6.2 (same number in both IEEE Std 802-2014 and P802-REVc/D1.)  

So my concern becomes would deleting subclause 6.2 leave us without an overarching requirement that is applied to all PHYs.  Does the Error Ratios requirements in Std 802 serve us (802.3) in evaluating PHY proposals; or is analysis of detected and undetected error ratios so entrenched in our culture that we no longer need Std 802 subclause 6.2.  

The feeling I got from the wireless participants in today’s call was that they are happy not having Error Ratio specifications in Std 802, and with the complexity of their encodings and one wireless type only having a CRC-16 (and thus much worse false packet acceptance than that specified for wired/optical links.  During the discussion it was also noted that the undetected error ratio (item b) is unmeasurable, only mathematically calculated assuming the link meets item a requirements.  

All participating in the P802-REVc discussion today on this topic, I think, understood how error ratio quality has changed since 1000BASE-X 8b/10b PCS error multiplication (some link errors producing invalid symbols some producing multiple data bit errors).  Similarly there was recognition that, FEC or other error correction capabilities might change the effective link error ratio for the data that is then CRC checked by the MAC, and that the current text does not cover error correction in the current error ratio text.

Do I read between the lines correctly, that you would not object to subclause 6.2 being deleted for the next P802-REVc recirculation ballot because we have been specifying the appropriate requirements in recent PHY clauses?

—Bob

> On May 2, 2023, at 10:14 AM, George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx> wrote:
> 
> Bob - it's not just the tradition of 'life of the universe' for false packet acceptance, but 802.3 is full of frame loss (or in earlier test BER) requirements.  Most (if not all) of the recent phys have some kind of a frame-loss-rate specification in their clause.  
> 
> It is stated in different ways in different places.  Not sure whether this was your concern, as the "Error ratios" in 5.3 of 802rev is stated somewhat ambiguously both interms of the probablility that "a transmitted MAC frame is not reported correctly" (item a in 5.3), as well as the probability that an MSDU delivered contains an undetected error" (item b in 5.3).  While "a" would count frames that are marked errors, "b" would exclude (be tolerant of) them.  Which are we doing?  The big issue here is how FEC is considered.
> -george
> 
> See, for example:
> Clause 92:
> Differential signals received at the MDI from a transmitter that meets the requirements of 92.8.3 and have passed through the cable assembly specified in 92.10 are received with a BER less than 10–5.
> For a complete Physical Layer, this specification is considered to be 
> satisfied by a frame loss ratio (see
> 1.4.344) less than 6.2 × 10–10 for 64-octet frames with minimum interpacket gap.
> 
> Others are more explicit on the requirement:
> Clause 95:
> 95.1.1 Bit error ratio
> The bit error ratio (BER) shall be less than 5 × 10–5 provided that the error statistics are sufficiently random that this results in a frame loss ratio (see 1.4.344) of less than 6.2 × 10–10 for 64-octet frames with minimum interpacket gap when processed according to Clause 91.
> If the error statistics are not sufficiently random to meet this 
> requirement, then the BER shall be less than that required to give a frame loss ratio of less than 6.2 × 10–10 for 64-octet frames with minimum interpacket gap when processed according to Clause 91.
> 
> Clause 97:
> Differential signals received at the MDI that were transmitted from a 
> remote transmitter within the specifications of 97.5.3 and have passed through a link segment type A (specified in 97.6.1 and 97.6.3) are received with a BER less than 10–10 and sent to the PCS after link reset completion. This BER specification shall be satisfied by a frame loss ratio less than 10–7 for 125-octet frames. Operation on link segment type B is optional. If supported, the frame loss ratio shall also be met for link segments specified at 97.6.2 and 97.6.4.
> 
> Similarly, there are alien crosstalk tests which are specified in terms of meeting a frame loss ratio...
> 
> 
> 
> -----Original Message-----
> From: ROBERT GROW <bobgrow@xxxxxxx>
> Sent: Tuesday, May 2, 2023 9:40 AM
> To: STDS-802-3-DIALOG@xxxxxxxxxxxxxxxxx
> Subject: [802.3_DIALOG] Removing error ratio requirements from Std 802
> 
> Colleagues:
> 
> Today, working on P802-REVc comment resolution, a proposal was make to delete the error ratio text from Std 802.  My recollection is that we don’t have these requirements in Std 802.3 but have used the requirement in Std 802 as the basis for analyzing if PHY proposals are acceptable for basic PHY link error rate and for undetected error rate at the MAC service interface.  
> 
> The current Error Ratios text for wireless networks does not include normative requirements.
> 
> I’m asking those more expert than I on this for reaction to this proposal to delete subclasses 6.2 Error Ratios from P802-REVc/D1.0.
> 
> —Bob
> 
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