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@xxxxxxxxxxxxxxxxxxxx]
> > Reply To: jonathan.thatcher@xxxxxxxxxxxxxxxxxxxx
> > 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@xxxxxxxxxxxxxx]
> > > Sent: Tuesday, March 14, 2000 8:40 AM
> > > To: jonathan.thatcher@xxxxxxxxxxxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> > > 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@xxxxxxxxxxxxxxxxxxxx>
> > > To: <stds-802-3-hssg@xxxxxxxx>
> > > 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@xxxxxxxx
> > > > > [mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Roy Bynum
> > > > > Sent: Sunday, March 12, 2000 11:50 AM
> > > > > To: Jonathan Thatcher
> > > > > Cc: stds-802-3-hssg@xxxxxxxx
> > > > > 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
> > > > >
> > > > >
> > > > >
> > > >
> > >
> >