RE: PMDs and Customer requirements
Steve,
I understand the concern the distance objectives may not properly address
all of the market segments. However, it is all I have (along with the other
criteria of cost, tech feasibility, etc.) to try to sort out the verious
proposals. I remember the discussions around the objectives and the various
positions taken and, in many ways, we are simply replaying the discussion
today. But unless we revote on the objectives, I am obligated to meet them.
As to the straw poll, it would have been informational to see it done based
on representative vendor type, i.e. a straw poll among equipment vendors and
a separate one among PMD vendors. I have no doubt the PMD vendors strongly
endorse at least 5 PMDs because I know each camp is well represented. I also
know the equip vendors have coalesced around 3 PMDs for the reasons that
Steve Haddock presented.
I don't think any of the positions are strong enough to pass a motion with
the required 75% but I think each of them is large enough to block a motion
that doesn't include their favorite solution.
So as I said in Ottawa, we have two choices:
1. Try to compromise on a smaller set that we can pass.
2. Not pass anything and therefore delay the standard.
As always, I am open to suggestions if there is another path that I'm
missing.
My understanding is the "100m on installed fiber" objective requires the
850nm or 1310nm WWDM solution. The groups discussion to satisfy the "at
least 40km on SMF" by having a solution that can go 50-80km dictates 1550nm
Serial. Since the 1310nm WWDM also satisfies the middle objectives, many are
happy with this simple set.
Walt
> -----Original Message-----
> From: Swanson, Steven E [mailto:SwansonSE@xxxxxxxxxxx]
> Sent: Wednesday, May 31, 2000 9:40 AM
> To: '802.3ae'; 'Walter Thirion'
> Subject: RE: PMDs and Customer requirements
>
>
> Walt,
>
> The entire discussion around link length objectives on the
> reflector to this point has been fundamentally flawed. For
> reasons much different than those that Bruce provided, I
> agree that the discussion thus far is like comparing apples
> and oranges because they no not address the same customer segment.
>
> IEEE 802.3 has historically developed applications that will
> run over media defined by structured cabling standards like
> ISO/IEC 11801 and TIA 568. For these standards, the only
> lengths of significance have been:
>
> * 100m for the horizontal portion of the network
> * 500m for the riser portion of the network (building backbone)
> * 2km for the campus portion of the network (campus backbone)
>
> The 300m link length has gained some popularity recently due
> to the emergence of centralized architectures (vs.
> distributed architectures) as well as the fact that a
> significant percentage of the known building architectures
> could be supported at 300m.
>
> The development of the 10GbE Standard signalled a departure
> from just supporting Ethernet over Structured Cabling - we
> essentially have added three NEW customer segments that ARE
> NOT addressed by Structured Cabling Standards, namely:
>
> * Very, very short reach for connections between switches
> in the same room.
> * Medium long reach ( 10 to 40 km).
> * Very long reach (over 40 km).
>
> So, I could construct a very convincing argument that the
> 100m objective over installed multimode fiber is flawed
> because 10GbE IS NOT addressing the horizontal portion of the
> structured cabling network. To believe this is the case
> supports 10GbE to the desk in the near term which even the
> die hard optimist on the fiber side would be hard pressed to
> justify. And, even if it was the case, there is very little
> installed base of fiber in the horizontal portion of the
> network today.
>
> Now, what about the 300m space? I agree that an installed
> base of fiber exists in this space and we have an obligation
> to support that installed base. But I also strongly believe
> that we should give our customers an option for addressing
> that space. History shows that customers will deploy new
> media if it makes sense. If not, we would still see a large
> installed base of CAT3 copper in the horizontal. Yet cabling
> is generally replaced if a more cost effective solution
> exists for a given space. We seem to argue both ways on this one:
>
> * I am only going to support the installed base
> * or, if I have to install new media, I might as well
> recommend single-mode fiber
>
> Neither of these scenarios really reflects current market
> dynamics. Simply put, it boils down to economics. And when we
> look at the short reach application space being addressed by
> 10GbE, we know that 850 nm solutions will likely provide the
> economic rationale in that space. In addition, both the very
> short reach and the building backbone spaces are easily
> upgraded compared to the more difficult upgrade that has
> taken place in the horizontal portion of structured cabling.
>
> We can continue to debate the merits of each of these PMD
> options and hold the standard hostage or we can try to build
> consensus around a solution set that has majority support in 802.3ae.
>
> My recommendation is that we build consensus around the 5-PMD
> set that by our own straw poll showed a 2 to 1 margin of
> support in 802.3ae at the Ottawa meeting.
>
> Best regards,
>
> Steve
>
>
> > ----------
> > From: Walter Thirion[SMTP:wthirion@xxxxxxxxxxxx]
> > Sent: Tuesday, May 30, 2000 8:55 PM
> > To: '802.3ae'
> > Subject: RE: PMDs and Customer requirements
> >
> >
> > Chris,
> >
> > The 100m objective is a pretty standard based on multiple
> surveys over the
> > years for networking installations. At 100m, you can
> satisfy something like
> > 95+ per cent of the horizontal runs, wiring closets, etc.
> Most structured
> > wiring standards have, therefore, specified this distance
> as maximum, so it>
> > has become self fulfilling, i.e. installers specify all new
> horizontal runs>
> > to be less than 100m, wiring closets are placed in order to
> ensure the 100m
> > max, etc.
> >
> > The "installed base" part is relevant because of the
> reasons Bruce has
> > elaborated.
> >
> > I believe the 300m is for campus environments, building to
> building, etc.
> >
> > Walt
> >
> > > -----Original Message-----
> > > From: Chris Simoneaux [mailto:csimoneaux@xxxxxxxxxxxxx]
> > > Sent: Tuesday, May 30, 2000 7:47 PM
> > > To: 'Bruce Tolley'; Walter Thirion; '802.3ae'
> > > Subject: RE: PMDs and Customer requirements
> > >
> > >
> > > Bruce,
> > >
> > > My concern here is that we are letting the needs of the few
> > > drive the needs
> > > of the many...so to speak. As an equipment vendor, you must
> > > support any
> > > application that the customer brings to you. That's a fact
> > > we all would
> > > agree with. However, I disagree with basing the success of
> > > 10GbE on how
> > > well it supports the minority applications.
> > >
> > > Customers are typically adverse to "forklift upgrades". But
> > > in the end,
> > > it's a matter of economics. And the cost vs. profit of the
> > > upgrade is the
> > > determining factor. If most of the user's links are
> shorter than 100m
> > > (probably much shorter), then the approach to the system
> upgrade will
> > > usually be based on the short distance link and expand into
> > > the lower volume
> > > longer distance links, not the other way around.
> > >
> > > Embedded in this PMD selection process is the 850nm serial
> > > solution. It
> > > clearly offers a solution for the 300m objective. It also
> > > offers added
> > > value of lowest cost, simplistic interconnections for all MM
> > > fibers up to
> > > 28m and most 50um MM fibers up to 86 meters. If technology
> > > proliferation is
> > > important, then 850nm serial should be a choice as it has
> > > several vendors
> > > that are doing actual link testing. And one that is actively
> > > demo'ing in
> > > the public forum. Ask that of any WDM solution. With all of
> > > it's benefits,
> > > why would the group not include the 850nm solution? Maybe
> > > someone can help
> > > me understand that.
> > >
> > > Also, I must respectfully ask for someone out there to inform
> > > me why the
> > > "100m over installed base", objective was chosen. Why not
> > > 50m? or 150m?
> > > Were there any scientific data or surveys used? Don't
> > > misinterpret, this is
> > > not a "knock" on the 802.3ae process. It's merely a question
> > > that's been
> > > bugging me for a while now.
> > >
> > > Finally, I would suggest we base our PMD solution set
> > > opinions on straw
> > > polls where all participants have an opportunity to vote.
> > > Informal straw
> > > polls can be misleading. Each subgroup within the 802.3ae
> > > seems to have an
> > > opinion on the PMD issue. However, we should not forget
> > > about the user
> > > community. The only user that stood up and voiced an
> opinion (that I
> > > remember) during the Ottawa meeting was MCI/Worldcom, and I
> > > believe they
> > > stood in support of 850nm serial. Correct me if I'm wrong.
> > >
> > > Chris
> > >
> > > -----Original Message-----
> > > From: Bruce Tolley [mailto:btolley@xxxxxxxxx]
> > > Sent: Tuesday, May 30, 2000 9:49 AM
> > > To: Walter Thirion; '802.3ae'
> > > Subject: PMDs and Customer requirements
> > >
> > >
> > >
> > > Walter:
> > >
> > > I have to reject the 2nd most popular set because it abandons
> > > the installed
> > > base of customers using their installed 62.5 nm 160 and 200
> > > MHz*km fiber.
> > >
> > > o Buildings will not move because of 10 GbE
> > >
> > > o The cabling infrastructure will not change overnight
> > > because of 10 GbE
> > >
> > > o Customers have a requirement to run 10 GbE on the same
> > > fiber links they
> > > run 1 GbE today
> > >
> > > o Customers have a requirement to use 10 GbE in building backbone
> > > applications on their installed fiber to distances of 200 to
> > > 300 meters.
> > >
> > > There is only one PMD proposal that runs on the installed
> > > fiber at building
> > > backbone distances: the 4 lambda 1300 nm WWDM proposal.
> If we do not >
> > > support the installed base, it will stall the market
> acceptance of 10
> > > GbE. Customers resist forklift upgrades.
> > >
> > > At the meeting in York I felt that the study group basically
> > > abandoned the
> > > installed base of customer by deleting the word "installed"
> > > out of the 300
> > > meter goal. We have to build a standard that supports the
> > > installed base
> > > of building backbones. There is no good reason to exclude the
> > > one proposal
> > > that supports this market segment.
> > >
> > > I have not hung up on the number of 3 PMDs but we have to
> > > have the one that
> > > supports the installed base of fiber out to 300 meters.
> > >
> > >
> > > Bruce Tolley
> > > Enterprise Line of Business
> > > Cisco Systems
> > >
> > >
> > >
> > > At 12:58 PM 5/28/00 -0500, Walter Thirion wrote:
> > >
> > > >First of all, thanks to everybody that presented PMD
> > > proposals at the last
> > > >meeting. I've sent my presentation to David Law, so it
> > > should be available
> > > >on the web site in the next couple of days.
> > > >
> > > >In listening to the discussion after my presentation and
> > > then going around
> > > >and talking to people, it feels to me like we're starting to
> > > converge. Not
> > > >there, yet, but making progress.
> > > >
> > > >The equipment manufacturers made it pretty clear they would
> > > like to see no
> > > >more than 3 PMDs in the standard. The PMD vendors have some
> > > concern that
> > > >using only 3 PMDs may sub-optimize certain objectives,
> > > however, they could
> > > >support the 3 PMD position if it is made clear which 3 PMDs
> > > the equipment
> > > >oems want.
> > > >
> > > >Based on an informal straw poll and anecdotal evidence, my
> > > opinion is the
> > > >first choice would be the set:
> > > >________________
> > > >850 nm WWDM
> > > >1310 nm WWDM
> > > >1550 nm Serial
> > > >________________
> > > >
> > > >If that set isn't feasible, then the 2nd most popular choice is:
> > > >________________
> > > >850 nm WWDM
> > > >1310 nm Serial
> > > >1550 nm Serial
> > > >________________
> > > >
> > > >Thoughts, feedback?
> > > >
> > > >Walt
> > > >___________________
> > > >Walter Thirion
> > > >Chair, IEEE 802.3ae PMD Sub-Task Force
> > > >301 Congress Ave.
> > > >Suite 2050
> > > >Austin, Texas 78701
> > > >Voice: 512-236-6951
> > > >Fax: 512-236-6959
> > > >wthirion@xxxxxxxxxxxx
> > > >___________________
> > > >
> > >
> >
>