RE: (SSIG) Taking the winning route
Ali,
The 55m distance is the result of taking the TIA FO-2.2 goal of 385MHz-km in
worst-case 62.5um fiber, combined with simple scaling from GbE, and
corroborated by the GbE link model. The lowest BW GbE spec shows 220m for
overfilled 160MHz-km. Scaling to 385 and multiplying by
(1.25Gbaud/10.3125Gbaud) actually gives 64m. Using reasonable inputs, the
GbE link simulator shows 2.62 dB of ISI for a 55m link and it hits 3dB
around 60m. So a good case is made for distances up to 55m or so for
worst-case fiber. I presented this at the March 802.3ae meeting along with
simulations for other link distances and other modal bandwidths, but all
with the same input parameters. One of those others was for a 100m length
of fiber having a 700MHz-km modal bandwidth, which yielded 2.66dB ISI. The
highest grade of fiber listed in the GbE SX spec is 500MHz-km for overfilled
launch. Is this your "Gigabit Ethernet grade" fiber? My simulation with
500MHz-km fiber, again presented at the March meeting, indicates it can
reach 75m. It seems perfectly plausible that an improved launch could
improve the modal bandwidth to about 700MHz-km to extend the reach to 100m.
I know of no organized effort to verify or standardize this. Do you have a
strong motivation to use it?
Hope this helps,
Jack
-----Original Message-----
From: ghiasi [mailto:Ali.Ghiasi@Eng.Sun.COM]
Sent: Friday, April 14, 2000 5:00 PM
To: stds-802-3-hssg@ieee.org; jljewell@picolight.com
Cc: mjbennett@lbl.gov; rtaborek@nserial.com
Subject: RE: (SSIG) Taking the winning route
Hi Jack
Could please clarify Ser. 850 sloution link distance of 55m. I belive this
is with 62.5um
fiber. You should be able to reach 100m with 50/125 gigabit Ethernet
grade.
Thanks,
Ali Ghiasi
Sun Microsystems
> From: Jack Jewell <jljewell@picolight.com>
> To: HSSG <stds-802-3-hssg@ieee.org>
> Cc: "'Mike Bennett'" <mjbennett@lbl.gov>, rtaborek@nserial.com
> Subject: RE: (SSIG) Taking the winning route
> Date: Wed, 12 Apr 2000 15:16:06 -0600
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>
> All,
>
> Let's clarify the difficult task of comparing different PHY costs by
looking
> at the different cost components for each PHY. In the context of this
> fascinating discussion, it is worth pointing out that 802.3z also did not
> "need" the SX solution. It was included as a cost-saving solution, and it
> currently represents roughly 80% of the volume sales of GbE
> opto-Transceivers. Somehow that MUST be relevant. In the table below I've
> added the GbE SX solution to the fray. Due to space constraints in email,
> we'll have to put up with abbreviations. More explanation below.
>
> GbE-SX GbE-LX Ser.-850 WWDM Ser.-1300
>
> Laser Wavelength and Tolerance
> 1 VCSEL 1 F-P 1 VCSEL 4 DFBs 1 VCSEL/DFB
> 850+-5% 1310+-3% 850+-0.9% 1310+-0.2% 1310+-1.1%
>
> Detector (# required)
> 1 1 1 4 1
>
> Fiber Coupling
> Tx 1 MM 1 SM 1 MM 4 SM 1 SM
> Rx 1 MM 1 MM 1 MM 4 MM 1 SM
>
> Mux/Demux
> N/A N/A Elect.4:1 Opt.4:1 Elect.4:1
>
>
> Tx + Rx IC's
> 1+1 @1G 1+1 @1G 1+1 @10G 4+4 @2.5G 1+1 @10G
>
> Fiber
> Inst MM Inst SM InstMM to 55m Inst SM/MM Inst SM
>
> COST 0.5X 1.0X 1.25X 4X 2X
>
>
> The laser wavelength tolerance is included since it can become a
significant
> cost issue in the 10GbE lasers, particularly for the WWDM lasers. In all
> cases, about 0.25% was deleted from the nominal wavelength tolerance due
to
> temperature variations. For WWDM, of course the wavelengths are
different;
> the 1310nm represents the wavelength region. Detector comparisons are
> straightforward. For fiber coupling it should be pointed out that
> single-mode (SM) coupling is more difficult on the transmit end and MM
> coupling is more difficult on the receive end. I took the WWDM Mux/Demux
> out of the optical comparison and put it into a general Mux/Demux
comparison
> row. This made sense because only the WWDM needs Optical Mux/Demux and
only
> the 10GbE serial solutions need Electrical Mux/Demux. For the fiber
> comparisons, "Inst" means "Installed." This should add a dash of realism
> for the final row which is the cost comparison which assumes 1.0X for the
> 1GbE-LX to keep it consistent with Rich's email.
>
> One topic of cost discussions is that of the 10Gig electronic IC's. While
> some vendors are currently charging ludicrously high prices, this is a
sign
> of current lack of availability. The cost of the actual
processed/packaged
> silicon is not high. For long term prediction of IC costs, put it this
way.
> Who has ever bet against the scalability of Silicon - and won?
>
> Jack Jewell
>
>
>
> -----Original Message-----
> From: Mike Bennett [mailto:mjbennett@lbl.gov]
> Sent: Saturday, April 08, 2000 5:50 PM
> To: rtaborek@nserial.com
> Cc: HSSG
> Subject: Re: (SSIG) Taking the winning route
>
>
>
> Rich,
>
> I should have read more carefully. Somehow I got the idea you were
talking
> about High
> Bandwidth MMF. The relative cost estimate is very informative. Thanks,
>
> Mike
>
> Rich Taborek wrote:
>
> > Hi Mike,
> >
> > My comment on Serial solutions was with respect to the installed based
of
> MMF,
> > which is "FDDI grade" 62.5 um MMF as I understand it. The bandwidth of
> this
> > fiber @ 850 nm is typically no more than 200 MHz*km. At 10.3125 GBaud,
> this
> > translates to roughly:
> >
> > 200 MHz*km
> > --------------- = ~39 meters (the fastest signaling rate is 1/2 the
> Baud.
> > This number is inflated since it does
> > 10.3125 GBaud/2 not consider laser rise/fall time
which
> > corresponds to a higher effective signaling BW)
> >
> > Serial 850 nm solutions can easily achieve 100 m, but require new
> "enhanced"
> > MMF. This fiber does not correspond to the installed fiber base.
> >
> > Assuming that by VCSEL, you mean "serial VCSEL at 850nm" for purposes of
> cost
> > comparison, I estimate the cost differences between the various PHYs as
> (very
> > roughly):
> >
> > 1 GbE LX PHY current cost = 1
> > 10 GbE Serial VCSEL @ 850 nm in (2002) = 2-3
> > 10 GbE WWDM @ 1300 nm in (2002) = 3-4
> > 10 GbE Serial 1300 nm in (2002) = 2-4
> >
> > Best Regards,
> > Rich
> >
> > --
> >
> > Mike Bennett wrote:
> > >
> > > Hi Rich,
> > >
> > > I have a few questions for you: What distance would you say the 850nm
> serial VCSEL
> > > solution would reach? If 100m is not possible for serial VCSEL at
> 850nm, please
> > > explain why not. What would you estimate the relative cost difference
> between the VCSEL
> > > and 1300nm WWDM PHYs will be, say normalized to current LX PHYs?
> > >
> > > Respectfully,
> > >
> > > Mike Bennett
> > > Lawrence Berkely Lab
> > >
> > > Rich Taborek wrote:
> > >
> > > > Martin,
> > > >
> > > > I apologize, I should have included a bit more detail with my last
> response. I'm
> > > > currently way backed-up with reflector traffic for the week and now
> see that my
> > > > response left out some details.
> > > >
> > > > WWDM 1300nm is the only strongly supported PHY proposal which
> addresses the
> > > > intalled base of MMF.
> > > >
> > > > No Serial solutions, including the 850nm serial VCSEL solution,
> address the
> > > > installed base of MMF at reasonable distance. I peg this disatance
at
> 100m as
> > > > does the corresponding distance/cable plant objective.
> > > >
> > > > The point of my previous note was that the 850nm serial VCSEL
solution
> over
> > > > enhanced MMF meets only one distance/cable plant objective, whereas
> WWDM 1300nm
> > > > meets the same one plus three others, rendering it as a much more
> flexible and
> > > > encompasing solution. In simply counting objective checkmarks, it's
> 4-to-1 in
> > > > favor of WWDM.
> > > >
> > > > We all agreed to HSSG objectives. It's time to select PHY's
according
> to these
> > > > objectives. I agree with Vipul's picks.
> > > >
> > > > --
> > > >
> > > > Best Regards,
> > > > Rich
> > > >
> > > >
> > > > Martin Nuss wrote:
> > > > >
> > > > > Of all the MM-fiber PMD proposals, only the 850nm serial VCSEL
> solution over the
> > > > > new high-performance fibers has so far been shown to work under
> stressed systems
> > > > > conditions, with Bit Error Rate measurements and careful analysis
of
> the systems
> > > > > impairments to support that, and working with VCSELs from many
> vendors. The
> > > > > suggestions below are highly puzzling to me...
> > > > >
> > > > > Martin
> > > > >
> > > > > 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@nSerial.com
> > Santa Clara, CA 95054 http://www.nSerial.com