Re: [10GMMF] TP-3 Stressors
Piers,
I am not sure what lower cost means but I do know that we have changed
our objectives and that change may make your priorities difficult to
attain. Specifically, I see the requirement to now be:
14. Purpose of Proposed Project:
This project will define a lower-cost, 10Gb/s serial PHY that supports a
link distance of at least 300m over installed FDDI-grade multimode
fiber. The specification should enable migration to smaller form factor
pluggable modules.
At 220m, I think we could have met all of your priorities; at 300m, the
challenge is much more difficult. If we insist on going back to the
PAR, maybe we should de-rate the link length to 220m (as originally
stated) and move forward. I do realize that "300m" is "at least 220m"
but I think everyone would feel much more comfortable in meeting your
priorities at 220m than at 300m.
I remain opposed to a mentality that LRM can somehow meet a lower bar
than previous standards because our PAR "states so."
Best regards,
Steve
-----Original Message-----
From: owner-stds-802-3-10gmmf@IEEE.ORG
[mailto:owner-stds-802-3-10gmmf@IEEE.ORG] On Behalf Of Piers Dawe
Sent: Tuesday, April 19, 2005 10:19 AM
To: STDS-802-3-10GMMF@LISTSERV.IEEE.ORG
Subject: Re: [10GMMF] TP-3 Stressors
Norm,
The more you stand back from the detail, the easier it is to understand!
Item 14 of the PAR says:
14. Purpose of Proposed Project:
This project will define a lower-cost, 10Gb/s serial PHY that supports a
link distance of at least 220m over installed FDDI-grade multimode
fiber. The specification should enable migration to smaller form factor
pluggable modules.
As I see it, our priorities are:
Acceptable cost
Acceptable heat and size possibilities
Acceptable timescale
This means we must set the bar to what is practicable and high yielding
in 2005. We don't have to agree whether any limitations are
"fundamental". We don't (and cannot precisely) tie TP3 testing to
coverage in the field. We know that for any performance level, somebody
somewhere can say "if you had made performance a little better my old
fiber would have worked with LRM". We should not be diverted by such
objective creep because it is a journey with no end.
All, we need to do more to show what is practicable. In particular, we
need to prove by experiment that we have a correct and viable
combination of noise loading and stressors in the TP3 test. Until we
have factored noise loading in, we cannot sign off the stressors.
Piers
> -----Original Message-----
> From: owner-stds-802-3-10gmmf@IEEE.ORG
> [mailto:owner-stds-802-3-10gmmf@IEEE.ORG]On Behalf Of Norman Swenson
> Sent: 18 April 2005 21:40
> To: STDS-802-3-10GMMF@LISTSERV.IEEE.ORG
> Subject: [10GMMF] TP-3 Stressors
>
> I would like to better understand the position of those
> advocating a limit of PIE-D in the range of 3.8-4.0 for the
> TP-3 stressor selection. I believe we can make progress on
> the reflector versus taking up weekly TP-3 call time to
> debate this issue.
>
> So far, as I understand the arguments for a PIE-D of 3.8-4.0,
> they are:
>
> 1) Real-world fiber will show dynamic variation in IPR
> that will degrade equalizer performance compared to that
> measured with a static TP-3 test, which somehow leads to a
> cliff in real-world performance if we set the PIE-D value too
> high in the TP-3 stress test
> 2) Cost-effective and power-efficient EDC chips can be
> produced that achieve performance in this range
>
> Argument (1) would seem to push for higher performance
> requirements in the static TP-3 test, since margin must be
> built into the static test to allow for unmodeled dynamic impairments.
>
> Argument (2) has been put forward as though there is some
> fundamental limitation that prevents cost-effective and
> power-efficient EDC chips from being produced that can
> equalize PIE-D values higher than 4.0 dB. I am very
> interested in learning more about the theoretical or
> experimental basis for concluding that cost-effective,
> power-efficient EDC chips cannot perform beyond the 3.8-4.0
> dB range that has been proposed as a performance metric.
>
> Until recently, the committee has focused on quantitative
> analysis to determine performance requirements for EDC based
> on theoretical models and measured data of optical fiber,
> with an implicit, if not explicit, goal of 99% coverage of
> 300m OM-1 fibers. Lately, there has been a shift away from
> considering the percentage of the installed base that can be
> covered to setting PIE-D objectives independently of coverage
> requirements. I do not understand the significance of PIE-D
> requirements if they are not put in the context of the
> percentage of the installed base that the PIE-D corresponds
> to. Without such context, the numbers can be arbitrarily
> chosen without any real-world significance.
>
> Thanks to any who can help me better understand the arguments
> for setting PIE-D limits to such a low value compared to that
> required to achieve 99% coverage.
>
>