RE: Equalization
Walt,
The right ones to include are:
850 Serial
850 CWDM
1310 Serial
1310 CWDM
1550 Serial
The standard could move forward very efficiently - no debate over objectives, no debate over band-aids, no debate over how many, etc. My recommendation to the committee is to support these PMDs in the standard. Individual companies and customers can then decide whether to support all of them, none of them, or some number in between. The standard sets expectations in the marketplace and encumbers noone. All of these PMDs have what I call "a critical level of support" on both sides - customers AND vendors. In this case, it is better at this point in time to include rather than exclude.
Best regards,
Steve
> ----------
> From: Walter Thirion[SMTP:wthirion@jatotech.com]
> Sent: Saturday, July 22, 2000 12:35 AM
> To: stds-802-3-hssg@ieee.org
> Subject: RE: Equalization
>
>
> I would really like for us to get away from the 3 PMD vs 5 PMD discussion
> and determine which PMDs are the right ones to include in the standard,
> whether it's 2, 3, 4, 5 or (hopefully not) "more than 5".
>
> Walt
>
>
> -----Original Message-----
> From: NetWorthTK@aol.com [mailto:NetWorthTK@aol.com]
> Sent: Friday, July 21, 2000 10:00 PM
> To: vipul.bhatt@finisar.com; stds-802-3-hssg@ieee.org
> Subject: Re: Equalization
>
>
>
> Vipul:
>
> It is a good summary. They are all true.
>
> However, we know all these facts for quite a while, and they are not new to
> us.
> They are not simple problems to be resolved overnight. It will take
> systematic approach and time to solve. I do not expect a miracle in
> September to come out all answers -- rush, rush does not produce miracle.
>
> Be practical, solid and smart to approach any problem.
>
> What I do not understand is why some people have to limit to 3 PMD only.
> There is no justified reason at all to insist 3-PMDs; as a result, the 3-PMD
>
> is forcing us to produce a miracle. GIVE US A BREAK !! A successful
> project
> is always completed by practical approaches, but not by a miracle.
>
> We can vote 5 PMDs in, then we can concentrate next whole year to resolve
> all
> those issues -- this is practical, and doable.
>
>
> Regards,
>
> Ed Chang
> NetWorth Technologies, Inc
>
>
> Dear colleagues,
>
> Okay, so where are we? Let me review what I think I have heard so
> far.
>
> Yes, the idea of 10G Serial on installed MMF is interesting, but
> there are a couple of holes in the proposal, including bad timing.
> Here is the summary, followed by holes.
>
> 850 nm Serial solution:
> -----------------------
> - Will benefit from TIA FO 2.2 Encircled Flux and Restricted Mode
> Launch work.
> - Offset Launch jumper not required.
> - Start with 385 MHz-Km bandwidth assumption on installed MMF.
> - Add 6 dB equalization to support 100 meters operation, additional
> 9.54 dB to support 300 meters. Equalization has to be adaptive, in
> the sense that impulse response will be different for each link. It
> must overcome severe DMD in some cases. With Encircled Flux launch,
> for a given link, the impulse response will not vary significantly
> with time, so it can be assumed as time-invariant or very slowly
> varying in time.
> - Potentially, end up with a total of 3 PMDs that meet all 5
> Objectives.
>
> 1310 nm Serial solution:
> -----------------------
> - Will benefit from EMB work done with 802.3z.
> - Offset Launch jumper is required.
> - Start with 500 MHz-Km bandwidth assumption on installed MMF.
> - Add 4 dB equalization to support 100 meters operation, additional
> 9.54 dB to support 300 meters. Equalization has to be adaptive in
> the sense that impulse response will be different for each link. It
> must overcome severe DMD in some cases. With offset launch, for a
> given link, the impulse response will not vary significantly with
> time, so it can be assumed as time-invariant or very slowly varying>
> in time.
> - Potentially, end up with a total of 2 PMDs that meet all 5
> Objectives.
>
> List of holes:
> -------------
>
> 1. It hasn't been established that Encircled Flux over a randomly
> selected fiber from installed base will ensure 385 MHz-Km bandwidth
> (850 nm) with a high degree of statistical confidence. Gair's
> suggestion of tagging an RML-compliance condition is one possible
> solution. We need to know if that suggestion will be acceptable to
> 802.3ae end users and system integrators.
>
> 2. It hasn't been established that 10G equalization is feasible. By
> feasible, I mean something like - a demonstrable solution before the
> Working Group Ballot, capable of overcoming severe DMD, consuming
> less than 3 watts, with a cost comparable to that of other
> components, backed by technical presentations in September that
> instill a high degree of confidence in the 802.3ae members.
>
> 3. Perhaps it is too late. There is a high likelihood that at the
> September Interim, motions to adopt other PMDs that meet Objectives
> 1 and 2 will pass.
>
> Hole 1 can be bypassed by adopting a 1310 nm Serial solution. Hole 2
> can't be plugged until we have heard presentations from DSP experts
> in September. Hole 3 is the most regrettable. I don't know how to
> plug it. Jonathan, Walt, do you have any comments or suggestions?
>
> Thanks,
> Vipul >>
>