Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

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
> >  
> > 
> > 
> > 
> > 
> 
>