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To
re-iterate the point that Dan made yesterday, I would add to the feasibility
list:
DSP
feasibility for the above configurations.
Note
that going from 100BASE-TX to 1000BASE-T, the symbol rate (125MBaud) didn't
change, and the DSP processing period was a relatively healthy 8ns. In the
proposed transition from 1000BASE-T to 10GBASE-T, the symbol rate goes up from
125MBaud to 833MBaud, which means the DSP processing period is reduced from 8ns
to 1.2ns (a factor of 6.7). Also, note the double whammy in that the number
of cancellation filter taps (Echo and NEXT) for the same coverage goes *up*
by the same factor (x6.7). So one could argue that to the first order the
canceller complexity is ~45x the canceller complexity of 1000BASE-T. Of course,
the processes that will be used for 10GBASE-T will be faster than those used for
1000BASE-T, but it's an issue that requires some thought and discussion
before we're all comfortable.
Vivek
Telang
Cicada
Semiconductor
While I understand the motive behind stressing
the benefits of DSP based ANEXT compensation, and installation based ANEXT
mitigation, I have to emphasize that these methods and their practical value
are subject to ongoing debate. For example, one of the ANEXT mitigation
methods is to insert patch cords of longer length/geater insertion loss into
the channel. This is not only counter-intuitive it has other problems as well,
such as the possibility of re-qualifying the channel for length and insertion
loss, as well as possibly violating TIA requirements for patch cord wire gauge
and insertion loss assumptions. For the formulation of the 5 critters, I
contend these arguments are non-starters. All of these things, however can be
cosidered and debated on their merits in the task group. Please try to focus
on establishing a baseline position that everyone can support by indicating
your support for the following options:
Class F at 100 meters
Class
E STP at 100 meters
Class E UTP at 50 meters
ADC feasibility for
above configurations
Commitment to develop:
Cabling performance standards for:
Class D
STP
Class D UTP
Retrofit based
mitigation techniques for:
Class E UTP > 50
meters
Class D STP ?
Class D UTP
(dependent upon result of cabling standards developed
above)
DSP based ANEXT
cancellation
ADC feasibility for the above
configurations
Based upon level of support for these objectives, we can
add new objectives or delete/augment. Remember, the objectives must have broad
support within the group to survive at higher levels of
approval.
Sterling
George Zimmerman wrote:
Presentations are given by individuals, not companies, but you can find
them on the 10GBASE-T study group site. Among those of note are a
January presentation from Stephen Bates, up to one just in July by Shadi
AbuGhazaleh & Rehan Mahmood (there are more on mitigation and on
feasibility studies, Ron Nordin & Vanderlaan, Albert Vareljian, Bijit
Halder all come to mind).
There really isn't any mystery here - going to shorter distances
increases the received signal proportionally, and mitigating alien NEXT
decreases the noise, hence, more capacity. What is more, because the
crossover point (signal/noise=1) occurs at a higher frequency, only
increasing the capacity further.
George Zimmerman
gzimmerman@solarflare.com
tel: (949) 581-6830 ext. 2500
cell: (310) 920-3860
-----Original Message-----
From: Sreen Raghavan [mailto:sreen-raghavan@vativ.com]
Sent: Tuesday, July 29, 2003 4:24 PM
To: George Zimmerman; sreen@vativ.com; 'DOVE,DANIEL J
(HP-Roseville,ex1)';
'Alan Flatman'; 'Kardontchik, Jaime'
Cc: '[unknown]'; 'Sterling Vaden'
Subject: RE: [10GBASE-T] PAR and 5 critters
George,
Please indicate which company's presentation has independently
confirmed
your claims, and where I can find such a presentation.
-----Original Message-----
From: George Zimmerman [mailto:gzimmerman@solarflare.com]
Sent: Tuesday, July 29, 2003 3:16 PM
To: sreen@vativ.com; DOVE,DANIEL J (HP-Roseville,ex1); Alan Flatman;
Kardontchik, Jaime
Cc: [unknown]; Sterling Vaden
Subject: RE: [10GBASE-T] PAR and 5 critters
Sreen & all -
I believe some clarification is in order.
What the presentation you reference from Portsmouth, New Hampshire
showed was that with an assumption of a high-degree of alien NEXT and
a
further assumption that it could not be mitigated in any way,
cat5e/cat6
could not support 100meter operation at 10G. This is a different
statement altogether as to whether cat5e/6 can support 10G either with
alien NEXT mitigation, or at shorter reaches, both of which have been
shown to yield sufficient capacity to allow 10G in numerous
presentations by multiple vendors.
The consensus proposal presented at San Francisco argued that even
without alien NEXT mitigation, there was a sufficient portion of the
installed base of 5e & 6 coverable to merit broad market potential
(>60%
installed base at 50m or less), and that in addition to SolarFlare
showing both receiver-based (DSP) and installation-practices based
alien
NEXT mitigation examples, other companies have now shown significant
alien NEXT mitigation through installation practices.
These developments significantly change the capacity relations you
refer
to, making 10GBASE-T practical on the economically feasible installed
base of cat5e & 6.
On your technical points for implementation, I respectfully disagree,
and we have put forward our requirements, and these have been
confirmed
by at least one independent presentation.
George Zimmerman
gzimmerman@solarflare.com
tel: (949) 581-6830 ext. 2500
cell: (310) 920-3860
-----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
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