RE: more on : IEEE 802.3 Requirements

["Buckman, Lisa" <lbuckman@xxxxxxxxxxxxxxx>]

Bob,
I only stated the 160MHz*km bandwidth-distance number to make it clear that
I was talking about the installed base of MMF.  Thanks for pointing this
out.  

The WWDM approach that I was referring to is the 1310-nm approach discussed
by Hewlett-Packard Laboratories at the last GbE meeting.  In this case,
approximately a 300 m link length would be possible using the 500 MHz*km
MMF.  The wavelengths that we are proposing for this window are 1280, 1300,
1320, and 1340 - all within the window of specified wavelengths.  This wide
channel spacing allows for uncooled DFB lasers at the nominal wavelengths.

I believe that the MMF is not specified at 1550 nm.   This is an issue that
should be discussed if anyone proposes the use of WWDM at 1550 nm on MMF.  

Lisa
 

 

  

-----Original Message-----
From: Bob Mayer [mailto:bmayer@xxxxxxxxxxxx]
Sent: Monday, May 24, 1999 11:29 AM
To: Buckman, Lisa
Cc: 'msalzman@xxxxxxxxxx'; stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
Subject: Re: more on : IEEE 802.3 Requirements


Lisa,

As I'm sure you know, the 160 MHz*km is the bandwidth spec for the 850nm
wavelength window.  Are you suggesting that we could reach 300m using WWDM
at
the shorter wavelength?  If you are, I am assuming you are recommending we
leverage off the TIA 2.2 groups work on characterizing link bandwidth based
on
conditioned launches.  Please confirm.

Or are you recommending using WWDM around 1310nm?  For 1310, I believe the
standard bandwidth for the cables in this wavelength window is 500 MHz*km.
Using the offset patch cord, I agree that 300m is a reasonable distance that
we
should be able to support.

If you are recommending WWDM at the 1550nm window, do you know what the
bandwidth spec is for standard 160/500 MHz*km cable is in that wavelength
window?

Just want to make sure I understand your proposal clearly.

Thanks,

Bob Mayer
Cielo Communications

"Buckman, Lisa" wrote:

> Mike,
> In response to your message below, I wanted to remind you that one of the
> advantages of a WWDM (Wide WDM) approach to 10GbE is to support the
> 160MHz-km MMF installed base.  WWDM using 4 wavelengths should support
> approximately 300 m of the installed base of MMF.
>
> Lisa
>
>
> -----Original Message-----
> From: Michael M. Salzman [mailto:msalzman@xxxxxxx]
> Sent: Wednesday, May 19, 1999 11:30 PM
> To: stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> Subject: more on : IEEE 802.3 Requirements
>
> Hi Ed,
>
> I am uncomfortable as a standards body telling people that they should use
> fiber X to reach 300M and to then say, well if you want to run over
> installed base, try it and see how far you get.  We know that serial
streams
> at 10G or thereabouts, on 160MhzKm fiber will not even reach 100M.
> Realistically, some fibers out there will go to 150 or more.  But,
consider
> that the buyer will go to some trouble to set up a new, expensive trunking
> facility and they will schedule some down time to deal with it,
interrupting
> many users in the process.  It seems to me unlikely that a project manager
> in that position will want to rely on unknown properties of of current
> cable.  Furthermore, as the plant continues to age, what parameter will
> fail, how and when?  We already know that existing fiber is simply far
from
> capable of supporting the new rates.  It is not a matter of close but no
> cigar.  It is more than an order of magnitude difference in quality of the
> fiber.
>
> Therefore, my sense is that the project owner will decide up front whether
> to replace the fiber or not.  My guess is that on main trunks, they will
> replace them with single mode.  In many new applications they could put in
> high performance multi mode.  In impulsive applications (which will be
> scarce in the beginning) they will simply try to see if they can live with
> the installed base.  If a MAS or CWDM PMD is available, they might simply
> decide to try that one for their installed base applications.
>
> To your point about educating the masses of installers, experience teaches
> that it takes on the order of 5-10 years to inculcate an appreciable
> quantity of them about the stringent aspects of installations.  How many
of
> them really know the differnces between cables and various kinds of
fibers?
> how many still do not know the total panoply of procedures and equipment
to
> install Cat5 correctly?  I think we want our technology in the market
before
> much of this knowledge will become commonplace, therefore we need to
> enunciate a clear set of requirements in a black and white manner for
these
> people to follow.
>
> mike
>
> > -----Original Message-----
> > From: Chang, Edward S [mailto:Edward.Chang@xxxxxxxxxx]
> > Sent: Wednesday, May 19, 1999 06:29
> > To: msalzman@xxxxxxxxxx; stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> > Subject: RE: IEEE 802.3 Requirements
> >
> >
> > Mike:
> >
> > You are right, I agree with your reasoning.
> >
> > The key points we are addressing is we should be flexible, convenient to
> > users, easily adaptable by market.  The rest of the headaches are upon
> > technical people(us) to make it happen.
> >
> > We will allow the installed bases to be used without modifications at a
> > shorter distances -- perhaps, 100, 200, or even 300 meters?, then
> > we can add
> > the extended distance with the new super fiber for longer
> > distances at added
> > material and installation costs.
> >
> > We have to device to products to make sure all levels of users are
> > affordable.  One area I do not quite agree with you is that: quote, "the
> > case of 10 Gig, due to its novelty and likely expense, I think we can
lay
> > down new standards for fiber to support it, and customers would go along
> > with the concept".  There are some users will fit into your expectation;
> > however, there are many will take a bite, only if it is truly
> > cost-effective, but not novelty.
> >
> > We do not have to worry about DMD, or very low-BW cables, which you
agree.
> > When users has problems with bad cables, they will find out by excessive
> > errors or re-tries.  They will call field servicemen to fix for
> > them.  Those
> > servicemen will understand how to identify the bad cables to be
> > removed from
> > service.  All we have to do is to educate field servicemen how to
identify
> > them.
> >
> >
> >
> > -----Original Message-----
> > From: Michael M. Salzman [mailto:msalzman@xxxxxxx]
> > Sent: Wednesday, May 19, 1999 5:32 AM
> > To: stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> > Subject: RE: IEEE 802.3 Requirements
> >
> >
> >
> > Hi Bruce, Ed, et al,
> >
> > My experience is that on average no installer tests fiber for any thing
> > other than connectivity.  To imagine that these fellows will carefully
> > follow some timeconsuming and deliberate procedure to check out
> > the cable is
> > wishful thinking.  You are right that DMD is an innate 'feature' of most
> > installed base fibers.  The ethernet community only recently
> > discovered its
> > ubiquity and impact.  Nevertheless we can expect the vast
> > unwashed masses to
> > blithely ignore any special handling and testing requirements untill
their
> > installation fails to come up and then they will search for causes.
> >
> > In the case of 10 Gig, due to its novelty and likely expense, I
> > think we can
> > lay down new standards for fiber to support it, and customers
> > would go along
> > with the concept.  For those stubborn souls who insist on deploying the
> > technology on existing fiber, I think the 10GEA can develop
> > recommended test
> > procedures and recommended equipment sets, and perhaps work with BICSI
to
> > develop a "gigabit technician" certification program.   If we do
> > not address
> > this prosaic aspect of our industry we are doomed to seeing more trial
and
> > error installations.
> >
> > Mike.
> >
> > > -----Original Message-----
> > > From: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> > >  Behalf Of Chang,
> > > Edward S
> > > Sent: Monday, May 17, 1999 06:36
> > > To: Bruce_Tolley@xxxxxxxx; Chang, Edward S
> > > Cc: Thomas Dineen; stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> > > Subject: RE: IEEE 802.3 Requirements
> > >
> > >
> > >
> > > Bruce:
> > >
> > > The 62.5 um fibers have been used for over 15 or 20 years.
> > > However, we just
> > > started paying attention to the DMD fibers two years ago.
> > Because of the
> > > small DMD population, industry did not paying attention to it.
> > > In fact, the
> > > DMD fibers have been with us since the graded index fibers were
> > > introduced.
> > > DMD fibers are defected parts like any other products having
> > > defected parts.
> > >
> > > In the past, the MM fibers, particularly 62.5 fibers, were only
> > used with
> > > LED sources over-filing the fibers, which is hardly capable of
> > creating a
> > > DMD results except low bandwidth.  It was until GbE requiring laser
over
> > > 62.5 um fiber, the DMD has not been identified as a detrimental
> > > problem.
> > >
> > > The fiber vendors do not characterize "DMD" as one of the parameters
in
> > > their commercial specification due to its very small, negligible
> > > population.
> > > As a result, no one really pays attention to verify it, unless an
> > > experienced engineer is purposely looking for DMD fibers.  Some
> > time, just
> > > to identify DMD fibers from the waveforms is not a simple job.
> > >
> > > Ed Chang
> > > Unisys Corporation
> > > Edward.Chang@xxxxxxxxxx
> > >
> > >
> > > ----Original Message-----
> > > From: Bruce_Tolley@xxxxxxxx [mailto:Bruce_Tolley@xxxxxxxx]
> > > Sent: Friday, May 14, 1999 5:29 PM
> > > To: Chang, Edward S
> > > Cc: Thomas Dineen; stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> > > Subject: RE: IEEE 802.3 Requirements
> > >
> > >
> > >
> > >
> > >
> > > Ed:
> > > As far as I know, hardly any "DMD fibers" have been identified to
date.
> > >
> > > Bruce
> > >
> > >
> >