RE: [802.3ae] XAUI Rj TR comment
Can anyone kindly tell me where is the current XAUI jitter
document and the agenda/plan for the future activities?
Thanks !
Mike
Wavecrest
> -----Original Message-----
> From: Jonathan Thatcher
> [mailto:Jonathan.Thatcher@xxxxxxxxxxxxxxxxxxxx]
> Sent: Thursday, August 09, 2001 4:32 PM
> To: HSSG_reflector (E-mail)
> Subject: RE: [802.3ae] XAUI Rj TR comment
>
>
>
> Kesling,
>
> Thanks for the redirection. Regarding the activity to define
> these terms,
> please be aware that the jitter test methodology being used
> in clause 52 is
> substantially different than the prior art referenced here from Fibre
> Channel and Gigabit Ethernet. Most of the concepts are the
> same (from a
> theoretical perspective), but much of the similarity ends there.
>
> I do not recommend that the XAUI group use this new method
> (though it should
> provide some advantages). But, please be aware and understand
> it during the
> course of refining the definitions.
>
> jonathan
>
> > -----Original Message-----
> > From: Kesling, Dawson W [mailto:dawson.w.kesling@xxxxxxxxx]
> > Sent: Wednesday, August 08, 2001 12:03 PM
> > To: HSSG_reflector (E-mail)
> > Subject: RE: [802.3ae] XAUI Rj TR comment
> >
> >
> >
> > All,
> >
> > I've been watching the reflector discussion but have been too
> > busy to reply.
> > I'd like to quickly give some background to help clarify the
> > situation.
> > Please don't shoot me - I'm only the editor giving some history!
> >
> > It has been universally understood in the XAUI group (until
> > recently) that
> > DJ is everything bounded and RJ is everything unbounded.
> > Furthermore, RJ has
> > been assumed to be Gaussian for the purspose of calculations.
> > Sinusoidal
> > jitter (SJ) is a subset of DJ. XAUI does not treat it
> > differently from DJ,
> > but only calls out an explicit level for the SJ component of
> > DJ. Jitter that
> > is bounded but not correlated to the data is also
> deterministic by the
> > working definition. XAUI does not call this out explicitly,
> but other
> > clauses may.
> >
> > Many people came into XAUI from different backgrounds, but
> > agreed to these
> > definitions for the sake of normalization and communication.
> > The work done
> > in MJS was helpful to XAUI and was the basis for these common
> > definitions.
> > Those who have more recently become active in XAUI seem to be making
> > different assumptions about the definitions of these jitter
> > terms. Other
> > definitions may be valid, but we should not change the underlying
> > definitions agreed to by dozens of participants and approved
> > in several
> > draft ballots at this late stage. There is nothing wrong
> with the XAUI
> > definitions as long as they are defined. The real problem is,
> > as Pat pointed
> > out, that they are not well defined in the document. This has
> > always been
> > intended to be done in Annex 48B but has not been finished
> > yet. I belive
> > that Anthony Sanders and Tom Lindsay are still working on it.
> > This annex
> > needs to be finished and submitted in the upcoming ballot
> > cycle so that
> > newcomers and standard readers can understand the meaning of
> > DJ and RJ as
> > used in XAUI (and the other clauses).
> >
> > In summary, I do not think there is anything inherently
> wrong with the
> > definitions assumed by XAUI and being written into Annex 48B
> > (based on MJS).
> > We should all use these definitions and get on with the
> > HOward's real issue
> > of limiting the RJ as the term has been defined by the group.
> > Please forgive
> > me that I probably won't be able to reply to any further
> > e-mails on this
> > topic. I only hoped to refocus us on the important issue
> > while I had a spare
> > minute between fires.
> >
> > -Dawson
> >
> >
> > -----Original Message-----
> > From: THALER,PAT (A-Roseville,ex1) [mailto:pat_thaler@xxxxxxxxxxx]
> > Sent: Monday, August 06, 2001 4:58 PM
> > To: Dennis Petrich; THALER,PAT (A-Roseville,ex1); Lindsay,
> Tom; Howard
> > A. Baumer; HSSG_reflector (E-mail)
> > Subject: RE: [802.3ae] XAUI Rj TR comment
> >
> >
> >
> > Dennis,
> >
> > The MJS document is referenced from an informative part of
> > our draft and it
> > is a TR. The terms are used in normative specifications in
> > our draft. The
> > definitions should be added to our draft because a
> > specification doesn't
> > mean anything if the quantity being specified is left ambiguous.
> >
> > Regards,
> > Pat
> >
> > -----Original Message-----
> > From: Dennis Petrich [mailto:dpetrich@xxxxxxxxxxxxx]
> > Sent: Wednesday, August 01, 2001 2:11 PM
> > To: 'THALER,PAT (A-Roseville,ex1)'; Lindsay, Tom; Howard A. Baumer;
> > HSSG_reflector (E-mail)
> > Subject: RE: [802.3ae] XAUI Rj TR comment
> >
> >
> >
> > Pat,
> >
> > The NCITS "TR-25-1999" MJS document provides definitions that can be
> > referenced for XAUI use to distinguish between the various
> > jitter types such
> > as RJ, DJ, DDJ, SJ and so on.
> >
> > Also, FC crosstalk work was done a while back and can be viewed at
> > T11/00-064v0 and T11/99-759v0. In the tests crosstalk showed
> > up as DJ. But
> > I'm sure these results would vary as a function of the
> > crosstalking data
> > rate and frequency content.
> >
> > Dennis
> >
> > -----Original Message-----
> > From: THALER,PAT (A-Roseville,ex1) [mailto:pat_thaler@xxxxxxxxxxx]
> > Sent: Wednesday, August 01, 2001 1:43 PM
> > To: Lindsay, Tom; Howard A. Baumer; HSSG_reflector (E-mail)
> > Subject: RE: [802.3ae] XAUI Rj TR comment
> >
> >
> >
> > Tom,
> >
> > Jitter always seems to be a difficult subject to sort out and
> > your remark
> > below caused me to do some checking on RJ vs. DJ.
> >
> > I've looked all through the 802.3 standard and our draft.
> > There doesn't seem
> > to be any definition of RJ or DJ. Processes can certainly be
> > random without
> > being random or Gaussian. Deterministic means if a set of
> > conditions is set
> > up we know what will result. The roll of a die is random
> > though the result
> > is bounded.
> >
> > If we are using dictionary words with a different or more
> > restricted meaning
> > such as random = Gaussian (or truncated Gaussian where the
> truncation
> > happens past 1E-12) then we should define our terms. Since
> we specify
> > deterministic jitter and total jitter, we should at least
> > have a reasonably
> > rigorous definition of "deterministic jitter."
> >
> > I also notice that in some places jitter is divided into RJ
> > and DJ, but in
> > other places in 47 it is RJ, DJ and sinusoidal. 52.9.10.4 (and the
> > equivalent subclause of 53) divide jitter into random,
> > deterministic and
> > bounded.
> >
> > Crosstalk is deterministic in that given a fixed adjacent
> > signal and a fixed
> > coupling function one can determine the crosstalk. However,
> > the crosstalk at
> > a receiver is often the result of multiple disturbers
> > coupling in each with
> > its own function and the signals aren't correlated to the
> > received signal.
> > Therefore, the sum of the crosstalk looks like a truncated
> > Gaussian. Even if
> > the definition of RJ is Gaussian up to at least 1E-12, it
> > isn't clear to me
> > that crosstalk would fall outside that definition. I don't
> > recall seeing any
> > studies on the distribution of crosstalk for XAUI or for our optical
> > receivers.
> >
> > I would expect crosstalk to be part of RJ rather than DJ.
> >
> > Regards,
> > Pat
> >
> > -----Original Message-----
> > From: Lindsay, Tom [mailto:tlindsay@xxxxxxxxxxxxxxxxxxxx]
> >
> > See below, Tom
> >
> > -----Original Message-----
> > From: Howard A. Baumer [mailto:hbaumer@xxxxxxxxxxxx]
> > Sent: Tuesday, July 31, 2001 11:36 AM
> > To: Lindsay, Tom; HSSG_reflector (E-mail)
> > Subject: Re: [802.3ae] XAUI Rj TR comment
> >
> > >>>>snip<<<<<
> > - We're still confused on how you would ever get 0.55UI of RJ. If
> > crosstalk adds so much jitter,
> > **TL - crosstalk is expected to be bounded, and therefore more
> > effectively deterministic (the definition of RJ is
> > unbounded/Gaussian to
> > least below 1E-12, and DJ is all other stuff).
> >
>