RE: [10GBASE-T] PAR and 5 critters
Dan -
EMI in the November tutorial - see the plot on page 13 of file
tutorial_1_1102.pdf. It is one result of many measurements made,
putting more signal and wider bandwidth on the line than any proposal to
date(you'll note the 12 dBm launch power, and a flat PSD is used).
I don't consider your questions on adversity, only a response to other
statements made here, and in considering the most straightforward ways
of attacking the problem. I will grant the group a very simple
statement - if you only look at 10GBASE-T using the most straightforward
techniques, it will look infeasible. However, I could argue that same
thing about many high-performance communications systems. One example
of how efficient filtering and the simple direct-form FIR model differ
in complexity can be found in pages 30-34 of the tutorial.
George Zimmerman
gzimmerman@solarflare.com
tel: (949) 581-6830 ext. 2500
cell: (310) 920-3860
> -----Original Message-----
> From: DOVE,DANIEL J (HP-Roseville,ex1) [mailto:dan.dove@hp.com]
> Sent: Wednesday, July 30, 2003 11:43 AM
> To: George Zimmerman; [unknown]
> Subject: RE: [10GBASE-T] PAR and 5 critters
>
> Hi George,
>
> I appreciate your response. I have gotten some <off reflector>
> admonition for raising questions that in my opinion are valid
> and would better be answered than ignored.
>
> I looked for EMI measurements in the November CFI presentation
> but must be looking in the wrong spot. Could you be more specific
> wrt to the presentation and page #?
>
> Regarding DSP feasibility, this is not my strong suit, but I love
> to be educated. Please don't consider my questions to be based
> upon an adversity, but rather concerned naivete.
>
> I acknowledge that analog processing will likely reduce the DSP
> complexity and may render feasibility in available processes. The more
> I learn in this area, the more interesting this discussion becomes to
me.
>
> Thanks for adding to the discussion.
>
> Regards,
>
> Dan Dove
>
> > -----Original Message-----
> > From: George Zimmerman [mailto:gzimmerman@solarflare.com]
> > Sent: Wednesday, July 30, 2003 10:59 AM
> > To: [unknown]
> > Subject: RE: [10GBASE-T] PAR and 5 critters
> >
> >
> >
> > In deference to some of Brad & Bob Grow's earlier admonition,
> > technical
> > feasibility is a matter of increasing confidence as time moves on.
The
> > tone of this discussion appears to have moved from the "can't
> > be done at
> > all" to "how much & what kind of silicon will it require". I
> > will assume
> > that we have entered that stage.
> >
> > We have presented our estimates of feasibility at about 6X 1000
BASE-T
> > and implementable in today's CMOS at the tutorial in November.
> > Regardless, there is no doubt that 90nm will be a commercial
processes
> > well before 10GBASE-T is through the standards process (at
> > the earliest
> > 2nd half of 2005), and 65nm will be commercial as 10GBASE-T begins
to
> > ramp in the subsequent years.
> >
> > In direct response to Dan's concern, there are a variety of
algorithms
> > that do not require closing the loop at the baud rate, (the
> > simplest of
> > which are the look-ahead algorithms which have obvious complexity
> > drawbacks), various reduced-state and lower-complexity forms are
well
> > studied in the literature, and have been implemented in commercial
> > products. (Dan - you will also see EMI measurements from November)
> >
> > In deference to earlier comments by Vivek & others, yes, if I
> > just take
> > the simplest form of design (direct-form FIR) and multiply up by the
> > baud rate & # of taps I get a huge complexity multipler
> > (something like
> > the 45X 1000 BASE-T), but just because the simplest-extension yields
a
> > huge complexity doesn't mean that it is non-feasible. Current art
in
> > efficient and multi-rate filtering algorithms don't scale linearly
as
> > the number of taps or processing speeds go up, and provide
significant
> > benefits (see November tutorial for an example, but these are
> > also well
> > studied in the literature).
> >
> > George Zimmerman
> > gzimmerman@solarflare.com
> > tel: (949) 581-6830 ext. 2500
> > cell: (310) 920-3860
> >
> > > -----Original Message-----
> > > From: DOVE,DANIEL J (HP-Roseville,ex1) [mailto:dan.dove@hp.com]
> > > Sent: Wednesday, July 30, 2003 8:38 AM
> > > To: 'sreen@vativ.com'; 'Alan Flatman'; 'Kardontchik, Jaime'
> > > Cc: '[unknown]'; 'Sterling Vaden'
> > > Subject: RE: [10GBASE-T] PAR and 5 critters
> > >
> > >
> > > > 2. Performing large number (x8 relative to 1000BaseT) of DSP
> > > > calculations at
> > > > 833MHz,
> > >
> > > Precisely my concern. I think it would be a useful exercise to
> > > calculate the loop timing necessary to make such a thing work, and
> > > then extrapolate to the process geometry that would enable it.
> > >
> > > I observed that 1000BASE-T did not really become solid in practice
> > > until .18u became available. There were some decent .25 designs,
but
> > > I suspect that corners were being "trimmed" to make timing close.
> > >
> > > Dan
> > >
> > > > -----Original Message-----
> > > > From: Sreen Raghavan [mailto:sreen-raghavan@vativ.com]
> > > > Sent: Tuesday, July 29, 2003 1:58 PM
> > > > To: 'DOVE,DANIEL J (HP-Roseville,ex1)'; sreen@vativ.com;
> > > > 'Alan Flatman';
> > > > 'Kardontchik, Jaime'
> > > > Cc: '[unknown]'; 'Sterling Vaden'
> > > > Subject: RE: [10GBASE-T] PAR and 5 critters
> > > >
> > > >
> > > > Dan:
> > > >
> > > > We are really referring to the theory (Shannon Capacity) when
> > > > we say 10Gbps
> > > > cannot be achieved over CAT-5e or CAT-6 cabling. Theory shows
> > > > that 10Gbps
> > > > can be achieved over CAT-7 cabling. Practical issues to
> > > > accomplish 10Gbps
> > > > over CAT-7 cabling include (assuming PAM-10 modulation):
> > > >
> > > > 1. Building an 11-bit effective ADC at 833 MBaud,
> > > > 2. Performing large number (x8 relative to 1000BaseT) of DSP
> > > > calculations at
> > > > 833MHz,
> > > > 3. DDFSE critical path to be implemented in 1.2 ns
> > > > 4. Building a linear transmit driver with an 833MGz bandwidth
> > > > & 40 dB SNR
> > > >
> > > > The above list by no means is exhaustive, but shows the
> > implementation
> > > > issues that need to be considered.
> > > >
> > > > Sreen
> > > >
> > > > -----Original Message-----
> > > > From: DOVE,DANIEL J (HP-Roseville,ex1) [mailto:dan.dove@hp.com]
> > > > Sent: Tuesday, July 29, 2003 1:09 PM
> > > > To: 'sreen@vativ.com'; 'Alan Flatman'; 'Kardontchik, Jaime'
> > > > Cc: '[unknown]'; 'Sterling Vaden'
> > > > Subject: RE: [10GBASE-T] PAR and 5 critters
> > > >
> > > > Hi Sreen,
> > > >
> > > > One thing that occurs to me on this point is the
> > difference between
> > > > theory and application. Specifically, how many process
> > actions have
> > to
> > > > take place within a baud time to close the loops on the
> > DSP and what
> > > > process geometry would be required to make that timing closure?
> > > >
> > > > I know that with 1000BASE-T, the theory was rock solid long
before
> > the
> > > > processes to implement it were reliable.
> > > >
> > > > Dan
> > > > HP ProCurve
> > > >
> > > > > -----Original Message-----
> > > > > From: Sreen Raghavan [mailto:sreen-raghavan@vativ.com]
> > > > > Sent: Tuesday, July 29, 2003 11:52 AM
> > > > > To: 'Alan Flatman'; 'Kardontchik, Jaime'
> > > > > Cc: '[unknown]'; 'Sterling Vaden'
> > > > > Subject: RE: [10GBASE-T] PAR and 5 critters
> > > > >
> > > > >
> > > > >
> > > > > Just to clarify, Vativ, Broadcom & Marvell presented capacity
> > > > > calculations
> > > > > at the Portsmouth meeting and showed that worst-case CAT-7
> > > > > (Class F) cabling
> > > > > had sufficient channel capacity to achieve 10Gbps throughput
> > > > > at 100 meter
> > > > > distance. The reason for "may be possible" statement in the
> > > > > conclusions was
> > > > > that the 3 PHY vendors felt that more work needed to be done
> > > > > on practical
> > > > > implementation issues before the conclusion could be
> > > > altered to a more
> > > > > definitive statement.
> > > > >
> > > > > In addition, we proved conclusively that there was NOT
> > > > > sufficient channel
> > > > > capacity on existing CAT-5e (Class D), or CAT-6 (Class E)
> > > > > cables to achieve
> > > > > 10 Gbps throughput.
> > > > >
> > > > > Sreen Raghavan
> > > > > Vativ Technologies
> > > > >
> > > > > -----Original Message-----
> > > > > From: owner-stds-802-3-10gbt@majordomo.ieee.org
> > > > > [mailto:owner-stds-802-3-10gbt@majordomo.ieee.org] On Behalf
> > > > > Of Alan Flatman
> > > > > Sent: Tuesday, July 29, 2003 9:51 AM
> > > > > To: Kardontchik, Jaime
> > > > > Cc: [unknown]; Sterling Vaden
> > > > > Subject: RE: [10GBASE-T] PAR and 5 critters
> > > > >
> > > > >
> > > > > Message text written by "Kardontchik, Jaime"
> > > > > >Was any reason given why it would not run on Class F ?
> > Was it for
> > > > > technical reasons or for marketing reasons ?<
> > > > >
> > > > > The 3-PHY vendor presentation made in Portsmouth
> > (sallaway_1_0503)
> > > > > calculated 49.36 Gbit/s capacity using unscaled Cat 7/Class F
> > > > > cabling. This
> > > > > figure was reduced to 37.71 Gbit/s with worst case limits.
> > > > Overall, I
> > > > > thought that this was a refreshingly realistic
> > presentation and I
> > > > > interpreted the summary statement "Capacity calculations with
> > > > > measured data
> > > > > indicate 10 Gigabit data transmission over 100m Cat 7 may
> > > > be possible"
> > > > > (slide 16, bullet 3) as overly cautious engineering judgement.
> > > > >
> > > > > So, what has changed since the May interim? Not the laws of
> > physics!
> > > > >
> > > > > Best regards,
> > > > >
> > > > > Alan Flatman
> > > > > Principal Consultant
> > > > > LAN Technologies
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> >