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

Re: [10GBASE-T] PAR and 5 critters

It is my impression that the lengths below are contingent upon using two
interconnects.  How does the use of two cross-connects effect length


Doug Coleman

                    Sterling Vaden                                                                                                   
                    <>             To:                                          
                    Sent by:                              cc:     "[unknown]" <>                            
                    owner-stds-802-3-10gbt@majordom       Subject:     Re: [10GBASE-T] PAR and 5 critters                            
                    07/30/2003 09:40 AM                                                                                              

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

    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.


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 Zimmermangzimmerman@solarflare.comtel: (949) 581-6830 ext. 2500
cell: (310) 920-3860

-----Original Message-----
From: Sreen Raghavan []
Sent: Tuesday, July 29, 2003 4:24 PM
To: George Zimmerman;; 'DOVE,DANIEL J


'Alan Flatman'; 'Kardontchik, Jaime'
Cc: '[unknown]'; 'Sterling Vaden'
Subject: RE: [10GBASE-T] PAR and 5 critters


Please indicate which company's presentation has independently


your claims, and where I can find such a presentation.

-----Original Message-----
From: George Zimmerman []
Sent: Tuesday, July 29, 2003 3:16 PM
To:; 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


further assumption that it could not be mitigated in any way,


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


installed base at 50m or less), and that in addition to SolarFlare
showing both receiver-based (DSP) and installation-practices based


NEXT mitigation examples,  other companies have now shown significant
alien NEXT mitigation through installation practices.

These developments significantly change the capacity relations you


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


by at least one independent presentation.

George Zimmermangzimmerman@solarflare.comtel: (949) 581-6830 ext. 2500
cell: (310) 920-3860

-----Original Message-----
From: Sreen Raghavan []
Sent: Tuesday, July 29, 2003 1:58 PM
To: 'DOVE,DANIEL J (HP-Roseville,ex1)';; 'Alan


'Kardontchik, Jaime'
Cc: '[unknown]'; 'Sterling Vaden'
Subject: RE: [10GBASE-T] PAR and 5 critters


We are really referring to the theory (Shannon Capacity) when we say
cannot be achieved over CAT-5e or CAT-6 cabling. Theory shows that


can be achieved over CAT-7 cabling. Practical issues to accomplish


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


3. DDFSE critical path to be implemented in 1.2 ns
4. Building a linear transmit driver with an 833MGz bandwidth & 40



The above list by no means is exhaustive, but shows the


issues that need to be considered.


-----Original Message-----
From: DOVE,DANIEL J (HP-Roseville,ex1) []
Sent: Tuesday, July 29, 2003 1:09 PM
To: ''; '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


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


processes to implement it were reliable.

HP ProCurve

-----Original Message-----
From: Sreen Raghavan []
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
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


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:[] 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.



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


(slide 16, bullet 3) as overly cautious engineering judgement.

So, what has changed since the May interim? Not the laws of


Best regards,

Alan Flatman
Principal Consultant
LAN Technologies