Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: [802.3ae] WIS test Pattern PRBS Generator Polynomial




Hi, Bruce,

I think you have a point. To the best of my knowledge, the polynomial to be used is as specified in O.150.

I think it might be useful to the reader if we had a (non-normative, superseded by O.150 in case of conflict) statement that provided the polynomial itself as well as the PRBS length. If you could submit such a comment against the next draft, that would be very useful. Ditto for the 2**31 - 1 polynomial.

Cheers,

- Tom

-----Original Message-----
From: Nepple, Bruce [mailto:bnepple@networkelements.com]
Sent: Monday, February 04, 2002 11:43 AM
To: stds-802-3-hssg@majordomo.ieee.org
Subject: RE: [802.3ae] WIS test Pattern PRBS Generator Polynomial


Ouch ---  I missed that comment.  Thanks for pointing it out.
My issue was that there are MANY 2**23-1 polynomials.  Which one
specifically is preferred or required was not specified, and there
was no comment indicating that the choice was implementation
dependent or to be determined in the future. 

Bruce

> -----Original Message-----
> From: Tom Alexander [mailto:Tom_Alexander@pmc-sierra.com]
> Sent: Monday, February 04, 2002 9:36 AM
> To: Nepple, Bruce; stds-802-3-hssg@majordomo.ieee.org
> Subject: RE: [802.3ae] WIS test Pattern PRBS Generator Polynomial
>
>
> Bruce,
>
> The PRBS for the mixed-frequency test pattern indeed uses a
> 2**23 -1 polynomial. This is explicitly described in the WIS
> clause (see lines 39-41 and 47-48 of page 397, lines 9-13 of
> page 398, and Figure 50-13 (payload field) on page 398). All
> these refer to Draft 4.0.
>
> Note that in the next draft of the WIS spec, there is a new
> (optional) additional test pattern introduced, as per the
> resolution of Comment #72 against Draft 4.0; this pattern
> uses a 2**31 -1 polynomial.
>
> Thanks,
>
> - Tom Alexander
> WIS Scribe
>
>
> -----Original Message-----
> From: Nepple, Bruce [mailto:bnepple@networkelements.com]
> Sent: Friday, February 01, 2002 9:36 PM
> To: stds-802-3-hssg@majordomo.ieee.org
> Subject: [802.3ae] WIS test Pattern PRBS Generator Polynomial
>
>
> I could find no definition of the WIS test Pattern PRBS
> generator polynomial in Clause 50 (or any other clause, for
> that matter).  I did find a reference to O.172 and in O.172 I
> found a reference to O.150, and in O.150 I found a definition
> for a 2**23 -1 length PRBS. (Section 5.6).  Is that the
> required generator for WIS?  Is there a reason that it is not
> specified?  Or, did I just manage to overlook it in the
> specification? (wouldn't be the first time).
>
> O.150 Section 5.6 specifies a 23 stage shift register with
> taps from stage 23 and stage 18 added (mod-2) and applied to
> the first stage. (I'd call it a x**23 + x**18 + 1 generator
> with input data = 0, but I'm not a math dude)
>
> Bruce
>