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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 independentlyconfirmedyour 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 andafurther assumption that it could not be mitigated in any way,cat5e/cat6could 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 basedalienNEXT mitigation examples, other companies have now shown significant alien NEXT mitigation through installation practices. These developments significantly change the capacity relations youreferto, 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 beenconfirmedby 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; 'AlanFlatman';'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 that10Gbpscan be achieved over CAT-7 cabling. Practical issues to accomplish10Gbpsover 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 DSPcalculationsat 833MHz, 3. DDFSE critical path to be implemented in 1.2 ns 4. Building a linear transmit driver with an 833MGz bandwidth & 40dBSNRThe above list by no means is exhaustive, but shows theimplementationissues 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 havetotake 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 beforetheprocesses 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 amoredefinitive 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 fortechnical 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,Ithought 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 bepossible"(slide 16, bullet 3) as overly cautious engineering judgement. So, what has changed since the May interim? Not the laws ofphysics!Best regards, Alan Flatman Principal Consultant LAN Technologies |