RE: more on : IEEE 802.3 Requirements

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

Mike,
Sorry for the confusion.  The WWDM approach that I was referring to is the
1310 nm version discussed at the last GbE meeting by Hewlett-Packard Labs.

At 1300 nm, the MMF will have a bandwidth-distance of 500MHz*km.  The GbE
spec supports distances of 550 m at 1.25 Gb/s.  I believe the fiber was
shown to support slightly longer distances, but that 550 m was chosen for
the standard.  At 2.5 Gb/s per channel, we should be able to reach about
300m (approx.).  The actual link length will depend on the encoding scheme
chosen and the link budget.

Lisa




-----Original Message-----
From: Mike Dudek [mailto:mdudek@xxxxxxxxxxxx]
Sent: Monday, May 24, 1999 11:37 AM
To: Buckman, Lisa
Cc: 'msalzman@xxxxxxxxxx'; stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
Subject: Re: more on : IEEE 802.3 Requirements


Why do you believe that WWDM with 4 wavelengths (ie at 2.5Gbit/s per
channel)
will support 300m of installed base, when our existing GBE specification at
1Gbit/s only supports 220meters.

"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
> > >
> > >
> >