RE: (SSIG) Taking the winning route
David,
As usual, well said. However, I think what everyone is asking here is that we have a level playing field. I believe that the 850nm serial camp has been more than forthcoming with actual test results utilizing components from multiple vendors on both the fiber side (Lucent, Alcatel, Corning etal) and the transmitter side (GORE, Cielo, Picolight etal). I am not sure the same can be said from the WWDM side. I have seen one presentation from the LX camp (Agilent) and one presentation from the SX camp (BLAZE). I am confident that the LX WWDM proposal will work over 100m of the installed base of multimode fiber and 2km over the installed base of single-mode fiber. I am not as confident that it will support 300m over the installed base of multimode fiber or 10km over the installed base of single-mode fiber - at least I haven't seen data that supports it. In fact, Agilent's initial presentation to the HSSG was very vague on the 300m distance and I believe stated support for 250m. The !
original specifications used in
On the single-mode side, I believe that data exists to 6km but not to 10km.
I also have some concern with the economics. Both Lucent and BLAZE have presented cost models showing that LX WWDM is the highest cost option. Lucent showed various upgrade paths (SX to SX, SX to LX, LX to LX, and SX to WDM) from GbE electronics to 10GbE. Now, the higher cost may be justified in the fact that the WWDM proposal is aimed at supporting 4 of the link length objectives. But individually, I believe each objective can be supported with a lower cost solution. So if I have a short reach application, should I be forced to use a higher cost alternative just because it supports longer distances that I don't need?
It is clear that both camps have some work to do in terms of convincing the committee and our customers of the benefits of the technology being proposed. We just want to have a fair opportunity to do so.
Best regards,
Steve
> ----------
> From: CUNNINGHAM,DAVID (HP-SanJose,ex1)[SMTP:david_cunningham@xxxxxxxxxxx]
> Sent: Tuesday, April 11, 2000 6:23 PM
> To: 'Giorgio Giaretta'; rtaborek@xxxxxxxxxxx; HSSG
> Subject: RE: (SSIG) Taking the winning route
>
>
> Georgio,
> I don't understand the technical issue that you are raising by the
> following comment:
>
>
> "So far I didn't see any convincing proof that WWDM can support 300m of
> installed base MMF (as a matter of fact any distance of installed MMF). I
> also expect that such proof if it will come, will require a significant
> amount of work
> as was the case for Gb Ethernet. It is in fact necessary to field test the
> transceivers with a large sample of existing "fairly unknown" installed MMF.
> A long painful process that potentially could delay the standard
> ratification (sounds familiar?)."
>
>
> The WWDM proposal is based on the work of the Gigabit Ethernet committee. In
> common with all 10GbE proposals it has used the Gigabit Ethernet link model
> as the basis for its link budget. The GbE link model is known to be very
> conservative. This is evidenced by the obvious robustness of the large
> number of Gigabit Ethernet links in operation today.
>
> Also, the multimode fiber (MMF) environment of the installed base was
> extensively investigated as part of the work of the Gigabit Ethernet
> Standardization (see list of publications at end of e-mail). It is therefore
> wrong to say that it is "fairly unknown". The MMF issue that required
> significant work was Differential Modal Delay (DMD). For 1000BASE-LX the
> standardized offset launch patch cord was proven to remove this as an issue
> - that's why it became part of the standard.
>
> So, given that the WWDM proposal is based on the work of Gigabit Ethernet>
> including the offset launch patch cord, as far as the installed base is
> concerned, what new parameters need to be investigated?
>
> Since you brought the issue up I have to question the following statement:
>
> "So why eliminate a solution that is the only one proven (multi vendor
> testing) to work to embrace an unproved solution that is recognized (I
> believe you agree with this although we disagree on the amount) to be more
> expensive?"
>
> I assume you are speaking on behalf of the serial MMF proposal that will use
> the newly developed MMF. I feel obliged to remind everyone of the following
> technical points:
>
> 1) The new high bandwidth MMF is not yet a standard,
> 2) It's final standards-based performance is therefore undefined (only
> target specifications are known),
> 3) The laser launch requirements to guarantee its performance are not yet
> defined,
> 4) The effect of link connectors on the performance of the standards-based
> version of the MMF fiber have yet to be specified.
>
> Also, to address the cost issue please remember that the installation of new
> fiber adds more cost to the user than can be saved by using lower cost short
> wavelength based transceivers.
>
> Points 1 - 4 are evidenced by the call for transceivers companies to engage
> in a further round of testing with the new MMF that was recently broadcast
> over this reflector. Given all of this it could be argued that proposals
> based on the new MMF have the higher risk for 10GbE. Technically, until
> points 1 - 4 have been addressed, by the standardization of the new MMF, the
> worst case 10 GbE link performance with the new MMF cannot be finalized.
>
> Furthermore, projects to write supplements to the IEEE 802.3 standard can be
> proposed at almost any time. From an IEEE 802.3 Standards point of view it
> might therefore be wise wait until the new MMF has been standardized.
>
> David.
>
> List of relevant publications
> -------------------------------
>
> "Evaluation of Gb/s laser based fibre LAN links: Review of the Gigabit
> Ethernet model", Mark C. Nowell, David G. Cunningham, Delon C. (Del) Hanson
> and Leonid Kazovsky, Opitical and Quantum Electronic, vol.32, pages 169-192,
> 2000.
>
> "A statistical analysis of conditioned launch for gigabit ethernet links
> using multimode fiber", Webster, M.,Raddatz, L.,White, I.H.,Cunningham,
> D.G., Journal of Lightwave Technology, vol.17, no.9, pages 1532-41,Sept.
> 1999
>
> "Influence of restricted mode excitation on bandwidth of multimode fiber
> links",
> Raddatz, L.,White, I.H.,Cunningham, D.G.,Nowell, C., IEEE Photonics
> Technology Letters, vol.10, no.4, pages 534-6, April 1998.
>
> "An experimental and theoretical study of the offset launch technique for
> the enhancement of the bandwidth of multimode fiber links", Raddatz,
> L.,White, I.H.,Cunningham, D.G.,Nowell, M.C. Journal of Lightwave Technology
> vol.16, no.3, pages 324-31 March 1998
>
> "The Gigabit Ethernet Modal Bandwidth Investigation", Chapter 10, Gigabit
> Ethernet Networking, Macmillan Technical Publishing, 1999. ISBN:
> 1-57870-062-0
>
> MBI group field test data can be found at:
> http://grouper.ieee.org/groups/802/3/z/mbi/index.html
>
>
>
> -----Original Message-----
> From: Giorgio Giaretta [mailto:giorgio@xxxxxxxxxx]
> Sent: Monday, April 10, 2000 11:32 AM
> To: rtaborek@xxxxxxxxxxx; HSSG
> Subject: Re: (SSIG) Taking the winning route
>
>
> Rich,
>
> even if we don't consider cost I would change your statement
> "WWDM meets all HSSG MMF objectives as well as SMF objectives to 10km."
> to WWDM POTENTIALLY meets (or WE HOPE WILL MEET) all HSSG MMF objectives as
> well
> as SMF objectives to 10 km.
>
> So far I didn't see any convincing proof that WWDM can support 300m of
> installed
> base MMF (as a matter of fact
> any distance of installed MMF). I also expect that such proof if it will
> come, will
> require a significant ammount of work>
> as was the case for Gb Ethernet. It is in fact necessary to field test the
> transceivers with a large sample of existing
> "fairly unknown" installed MMF. A long painful process that potentially
> could delay
> the standard ratification (sounds familiar?).
>
> So why eliminate a solution that is the only one proven (multi vendor
> testing) to
> work to embrace an unproved solution that
> is recognized (I believe you agree with this although we disagree on the
> amount) to
> be more expensive?
>
> I believe this point has been raised from other members before but so far no
> one
> has answered.
> Are you aware of any data that I didn't see?
>
> Giorgio Giaretta
>
>
> Rich Taborek wrote:
>
> > Vipul, Rob,
> >
> > It should be pointed out that a Serial 850nm solution only partially meets
> one
> > HSSG distance/cable plant objective: 300m on MMF. However, this MMF must
> be the
> > new, enhanced MMF. The Serial 850nmsolution addresses no SMF objectives
> >
> > WWDM meets all HSSG MMF objectives as well as SMF objectives to 10km.
> >
> > I agree with Vipul's choice of 3 PMDs as the best possible PMD set to
> address
> > HSSG HSSG distance/cable plant objectives.
> > Best Regards,
> > Rich
> >
> > --
> >
> > Vipul Bhatt wrote:
> > >
> > > Rob,
> > >
> > > Rob Marsland wrote:
> > > >
> > > > Finally, I hate to be annoying, but this is the SERIAL sig. Since
> when is
> > > > WWDM a serial solution?
> > > >
> > >
> > > There is nothing annoying about your question. I should answer. I
> believe it
> > > is in our (the Serial SIG's) best interest to rise above our Serial
> focus and
> > > recognize that an "all Serial" set of solutions that meets all the
> distance
> > > objectives is not something our customers are willing to sign up for. By
> > > proposing a set of three solutions - two of which are Serial - I am
> proposing
> > > a set that has the highest chance of being accepted by our customers and
> the
> > > majority of 802.3ae members. I understand you disagree, and I respect
> your
> > > opinion.
> > >
> > > Vipul
> >
> > -------------------------------------------------------
> > Richard Taborek Sr. Phone: 408-845-6102
> > Chief Technology Officer Cell: 408-832-3957
> > nSerial Corporation Fax: 408-845-6114
> > 2500-5 Augustine Dr. mailto:rtaborek@xxxxxxxxxxx
> > Santa Clara, CA 95054 http://www.nSerial.com
>