RE: Unified PMD vs. Unified PHY
Thanks here also.
One point, while there are many venues where a vote or survey might be
interesting, only one matters in the end, and that is with 802.3 voting
members. It would therefore also be reasonable to criticize the survey for
including attendees who will not be around in the long term.
jonathan
> -----Original Message-----
> From: Kameran Azadet [mailto:ka@lucent.com]
> Sent: Tuesday, March 14, 2000 2:03 PM
> To: Jones, Nevin R (Nevin)
> Cc: HSSG_reflector; 'jonathan.thatcher@worldwidepackets.com';
> ka@lucent.com
> Subject: Re: Unified PMD vs. Unified PHY
>
>
> Jonathan,
>
> here are some concerns I had:
>
> 1) I also noticed that there were 4 UniPHY options out of 7 total
> choices...
>
> 2) the spelling of the word "UniPHY" suggested a specific proposal
> (Howard Frazier). Maybe a more un-biased way of conveying the
> idea is to
> refer to, as a unified LAN/WAN PCS?
>
> 3) unified LAN/WAN sounds still a bit vague to me. It may be
> useful to give
> more detail. Do we mean:
>
> a) implement both LAN and WAN functions inside PCS (if
> SONET framing
> overhead is less than X %)
> b) use common packet delineation for both LAN and WAN
>
> ------------
>
> I am also a bit nervous about surveys in 802.3 that are related to WAN
> since not everyone in 802.3 is expert in WAN. for instance I personally
> don't know much about the requirements in WAN, except for what I
> hear from
> few WAN folks in 802.3.
>
> Should we get some more feed-back from the WAN experts (ISPs or equipment
> makers), since this clearly is intended for the WAN. I guess I am
> saying this
> but don't know how exactly it could be implemented. Is it crazy to do a
> similar survey in T1.X1 (I don't know how it works over there)?
>
> ------------
>
> Regards,
>
> Kamran
>
>
>
> "Jones, Nevin R (Nevin)" wrote:
> >
> > Jonathan:
> >
> > I did have a couple of concerns regarding possible areas of
> potential bias
> > in the survey.
> >
> > In the first place, I was uncomfortable with the fact that the UniPHY
> > occupied 4/7 (57%) of the option set for the first question.
> This has the
> > potential of creating an inherent "option bias" which could
> potentially skew
> > the results in the UniPHY direction.
> >
> > Secondly, since the independently optimized LAN and WAN PHY was
> perhaps a
> > more realistic option than the WAN only or LAN only options it perhaps
> > should not have been sandwiched between these and the UniPHY series of
> > options for fear of the "orphan effect".
> >
> > Perhaps the UniPHY series of options could have been shortened
> at, say ">20
> > %". In the same vein, maybe the independent optimized LAN/WAN
> PHY could have
> > had other options like "total cost equal to UniPHY cost" or
> perhaps "total
> > cost <=x% of UniPHY cost".
> >
> > With regard to the second question, the options read to me like
> a ranked or
> > sorted set. To minimize the potential for bias it would perhaps had been
> > better to have randomized the options.
> >
> > I have no sense of what the possible magnitude of bias in the
> survey results
> > is or even if it is significant enough to warrant undue concern.
> >
> > Best Regards,
> >
> > -Nevin Jones
> > System Architect
> > Lucent Microlectronics
> > 908-582-5343
> >
> > > ----------
> > > From: Jonathan
> > > Thatcher[SMTP:jonathan.thatcher@worldwidepackets.com]
> > > Reply To: jonathan.thatcher@worldwidepackets.com
> > > Sent: Tuesday, March 14, 2000 11:50 AM
> > > To: HSSG_reflector
> > > Subject: RE: Unified PMD vs. Unified PHY
> > >
> > >
> > > All,
> > >
> > > So far, I have received no negative feedback on the survey nor on the
> > > method. On the other hand, I haven't heard a great ground
> swell of postive
> > > feedback either.
> > >
> > > I welcome feedback from anyone that it interested. If you
> don't want to
> > > clog
> > > the reflector with traffic, send the feedback directly to me.
> > >
> > > On the assumption that the group felt the information was helpful and
> > > would
> > > like to drive down to lower levels, I would be happy to work
> on the next
> > > iteration.
> > >
> > > jonathan
> > >
> > > > -----Original Message-----
> > > > From: Roy Bynum [mailto:rabynum@mindspring.com]
> > > > Sent: Tuesday, March 14, 2000 8:40 AM
> > > > To: jonathan.thatcher@worldwidepackets.com; stds-802-3-hssg@ieee.org
> > > > Subject: Re: Unified PMD vs. Unified PHY
> > > >
> > > >
> > > > Jonathan,
> > > >
> > > > Thank you for the explaination. I am sure, given your
> justified desire
> > > to
> > > > reduce the number of PMDs that you will continue with the
> > > > iterations of the
> > > > survey at the next meeting.
> > > >
> > > > Thank you,
> > > > Roy Bynum
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: Jonathan Thatcher <jonathan.thatcher@worldwidepackets.com>
> > > > To: <stds-802-3-hssg@ieee.org>
> > > > Sent: Monday, March 13, 2000 5:04 PM
> > > > Subject: RE: Unified PMD vs. Unified PHY
> > > >
> > > >
> > > > >
> > > > > Roy,
> > > > >
> > > > > There are a rather large number of reasons why I did not
> extend the
> > > > > selection set in the first question. Primarily, it has to do
> > > > with the fact
> > > > > that a 2-dimensional question like the one I asked is already
> > > > significantly
> > > > > challenging. To have made this a 3-dimensional question would have
> > > made
> > > > it,
> > > > > in my mind, unanswerable. There are ways to take 3-dimensional
> > > questions
> > > > and
> > > > > reduce them to 2-dimensions, but to do this correctly
> requires several
> > > > > iterations of questions to confirm the many assumptions
> that are made
> > > to
> > > > do
> > > > > so. Without having the time to go through these
> iterations would have
> > > > forced
> > > > > me to impose my own interpretation upon the question,
> thus breaking
> > > all
> > > > the
> > > > > rules of conducting this type of survey.
> > > > >
> > > > > jonathan
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: owner-stds-802-3-hssg@ieee.org
> > > > > > [mailto:owner-stds-802-3-hssg@ieee.org]On Behalf Of Roy Bynum
> > > > > > Sent: Sunday, March 12, 2000 11:50 AM
> > > > > > To: Jonathan Thatcher
> > > > > > Cc: stds-802-3-hssg@ieee.org
> > > > > > Subject: Unified PMD vs. Unified PHY
> > > > > >
> > > > > >
> > > > > >
> > > > > > Johnathan,
> > > > > >
> > > > > > I was intending to ask you why you did not ask about
> unified PMDs
> > > > > > separate from a unified PHY as part of your survey but
> did not get a
> > > > > > chance. At the 10GEA technical meeting you were very
> adamant about
> > > > > > getting consensus for a small set of PMDs. I agree that
> > > > having a small
> > > > > > group of PMDs is preferable. Having a unified PHY in
> order to have
> > > a
> > > > > > small set of PMDs may not be preferable.
> > > > > >
> > > > > > The cost of the unified PHY, as presented, so far has been
> > > > very high in
> > > > > > the form of lost transfer rate. As it is, the unified PHY, as
> > > > > > presented, does not meet the objective to have a 10.000
> Gigabit MAC
> > > > > > data transfer rate (Gb-Mtr). Separate PHYs, LAN and
> WAN do meet the
> > > > > > objectives. Additionally, one of the scramble encoded WAN PHY
> > > > > > presentations was able to achieve an average 10.000 Gb-Mtr
> > > > transfer rate
> > > > > > by using IPG compression, which can be inferred to meet
> the 10.000
> > > > > > Gb-Mtr objective in addition to the 9.548 Gb-Mtr objective.
> > > > > >
> > > > > > A unified PMD set can support the block encoded LAN PHY and
> > > > the scramble
> > > > > > encoded WAN PHY, allowing both to meet the 10.000
> Gb-Mtr objective.
> > > > > > This will allow the PMD people to concentrate on the
> > > > technologies of the
> > > > > > PMDs with the consideration of a signaling range to support both
> > > PHYs.
> > > > > > It will also simplify the marketing of 10GbE by reducing the
> > > confusion
> > > > > > about distances and fiber types.
> > > > > >
> > > > > > As was demonstrated in some of the previous presentations
> > > > (SUPI and OIF
> > > > > > SERDES), it is possible to have unified PMDs without having a
> > > unified
> > > > > > PHY. If the question had been asked, would it have made a
> > > > difference to
> > > > > > separate the issues? If they are separate issues, as a
> I believe
> > > they
> > > > > > are, then should the survey be redone with that segregation?
> > > > Would this
> > > > > > have put less pressure on group to have a unified PHY
> and changed
> > > the
> > > > > > scaling of the responses?
> > > > > >
> > > > > > Thank you,
> > > > > > Roy Bynum
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > >