Re: [10GBASE-T] PAR and 5 critters
Dan
I completely agree with you. I think all these implementation issues need to
be considered very thoroughly in addition to Capacity considerations.
Sreen
----- Original Message -----
From: "DOVE,DANIEL J (HP-Roseville,ex1)" <dan.dove@hp.com>
To: <sreen@vativ.com>; "'Alan Flatman'" <a_flatman@compuserve.com>;
"'Kardontchik, Jaime'" <jaime@integration.com>
Cc: "'[unknown]'" <stds-802-3-10gbt@ieee.org>; "'Sterling Vaden'"
<sterlingv@bellsouth.net>
Sent: Wednesday, July 30, 2003 8:38 AM
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
> > >
> > >
> > >
> > >
> > >
> >
> >
>