RE: 850 nm solutions
But why does it matter? Why limit the users? Why not put in the table. It costs nothing. Just put in what the model and data tell us to. It is my opinion that a large percentage of 10GB style links are going to be very short, less than 10m. If you look at the way many fiber ports are being used today, many are in the 10m range. Also, since copper cables are going to be EXTREMELY challanged to go that distance at 10GB, why not let the market choose the lowest cost solution using 850nm VCSELs and 62.5um fiber? Why make the users pay a factor of two to ten increase in cost to cover this distance? It really seems kind of silly to me not to put in the link distances appropriate for ALL fibers for each PMD assigned. To get the 100m on installed base, that is the CWDM solutiuon. Part of the PAR also said new MMF, and that is achieved by 300m at 10GB (SERIAL). Just put in all the approaches, and all the cabling specs. It is the same argument that took place i!
n 1GigE... and we settled it that way, and it seems to me users are happy, and 85-90 percent of the links installed are SX. Cost drives the data com market MUCH MORE than the telecom market. If we want to enable this technology, there must be a truly low cost approach for short reach cabling.
Sent: Tuesday, April 18, 2000 10:40 PM
To: Tatum, Jim; Jaime Kardontchik; stds-802-3-hssg
Subject: Re: 850 nm solutions
the simple answer is that you will never meet 100m for installed orr 300m
for new fiber. A serial 850nm will barely meet 300m over new fiber, but will
be well below 100m for installed fiber.
----- Original Message -----
From: Tatum, Jim <JTatum@micro.honeywell.com>
To: Jaime Kardontchik <firstname.lastname@example.org>; stds-802-3-hssg
Sent: Tuesday, April 18, 2000 12:44
Subject: RE: 850 nm solutions
> I guess I don't understand all of the problems here...
> Why can't we have a serial solution at 850nm and 1310nm, 1550nm that
mirrors the 802.3Z approach, where we have a table that addresses each of
the fiber types. i.e. repeat the tables 38.2 and 38.5. Seems like an easy
thing to do, and straightforward. That is one PMD type. A second PMD type
would be the 4 wavelength WDM at 3.125GBd, with a similar table. To me
that is 2 PMD's, with options, with link lengths depending on what fiber
you have installed. The market has shown that 850nm technology is the low
> Jim Tatum
> (972) 470-4572
> -----Original Message-----
> From: Jaime Kardontchik
> Sent: Tuesday, April 18, 2000 2:07 PM
> To: stds-802-3-hssg
> Subject: 850 nm solutions
> Edward and all,
> Thank you Edward for your insight.
> There are have been in Albuquerque excellent presentations
> using 850 nm VCSELs by J. Yorks, P. Kolesar et al, F. Peters,
> R. Colla et al and J. Jewell. They were all targetted towards
> the new 2200 MHz*km MMF using 10 Gbaud lasers. Unfortunately,
> at this speed they cannot support the installed MMF (the
> eye closes at about 25 meters).
> However, there are two proposals using 850nm - 4WDM that
> do support both the installed MMF and the new 2200 MHz*km
> MMF. See the Albuquerque presentations:
> B. Wiedemann et al: "Evaluating CWDM 10GBASE-SX"
> J.E. Kardontchik et al: "850nm-4WDM-1.25Gbaud transceiver
> over MMF for 10 GbE"
> Both provide ample support for the new MMF: the first
> proposal, at 2.578 Gbaud, has a target of 550 meters, and
> the second proposal, running at 1.25 Gbaud, has a target
> of 1,000 meters. Hence, both meet with ample margin
> the minimum objective of the HSSG regarding the new
> 2200 MHz*km MMF, 300 meters.
> The 2.578 Gbaud proposal has a target of 100 meters on
> installed MMF. The 1.25 Gbaud proposal has a target of
> 160 meters on installed MMF. Hence, both meet also the
> minimum objective of the HSSG regarding the installed
> MMF, 100 meters.
> The 2.578 Gbaud proposal has the advantage of using
> on-off optical modulation. Its PCS, using 64/66, is new
> and needs still some work and debugging in the coming
> months. Work is being presently done in both areas to
> validate this proposal. It is a very good proposal.
> I happen to co-sponsor it ... :-)
> The 1.25 Gbaud proposal uses PAM-5 modulation, that
> is new to the optical community. However, it only needs a
> very small dynamic range (18-level ADC in the receiver),
> corresponding to an SFDR (Spurious Free Dynamic Range)
> of about
> SFDR = 20*log(18) + (2/3)*10*log(0.625e+9)
> = 84 dB*Hz^(2/3)
> This SFDR is well within the present VCSEL technology
> capabilities. (*) This proposal has the advantage that it reuses
> the 1000BASE-T PCS, that has already been debugged and
> standardized and some companies are already offering it
> in commercial products. It uses the same symbol rate as
> the 1 GbE optical transceivers, 1.25 Gbaud, simplifying
> the coexistence of 1 and 10 GbE transceivers on the same
> board and minimizing packaging and PCB costs and EMI.
> It could be the lowest cost 10 GbE system solution on MMF,
> both installed and new.
> The only area that needs detailed work, in order to meet
> the July 2000 schedule-milestone, is in providing actual
> 5-level pseudorandom stimulus to VCSELs at 1.25 Gbaud
> and measuring the actual performance of the optical link.
> My company has shown a lot of support towards developing
> the whole proposal. However, it does not have the means
> and optical expertise in this area and we will welcome
> any optical companies interested in performing these
> measurements and presenting them to the Task Force.
> These are the 850 nm choices.
> (*) See, for example:
> "Dynamic Range of VCSELs in Multimode Links"
> by: H.L.T. Lee, R.V. Dalal, R.J. Ram and K.D. Choquette
> IEEE Photonics Tech. Letters, vol 11, pp 1473-75, Nov 1999
> Jaime E. Kardontchik
> Edward Chang wrote on Mon, 17 Apr 2000 12:16:33 -0400:
> > Brad:
> > I appreciate your input, and we may have to speed up the proposal by
> > responding to some questions.
> > My main concern is that the sole technology, 850 nm VCSEL, which
> > today's cost-effective gigabit rate LAN market is not included in the
> > proposal. The VCSEL technology will continue to play the major role in
> > 10 GbE market to keep the cost affordable and to open up the market.
> > Following the lead by the more affordable technology, the more
> > technologies will be demanded by the market needs. This was the
> > happened in the Gigabit rate market.
> > The mass market is always looking for the top performance at lowest
> > It is true that July is approaching very quick, and we should speed up
> > process.
> > Nevertheless, our good common since taught us that do it "Right" is the
> > to the success.
> > I believe all of us had some regrettable experience: overly rigid to
> > the rules set at the beginning, and not enough flexibility to
> > the reality uncovered later.
> > The mission of HSSG is to provide the right directions for 10 GbE
> > therefore, we should continue to evaluate the over all progress and
> > good balance.
> > Regards,
> > Edward S. Chang
> > NetWorth Technologies, Inc.
> > EChang@NetWorthtech.com
> > Tel: (610)292-2870
> > Fax: (610)292-2872