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RE: PMDs and Customer requirements


My concern here is that we are letting the needs of the few drive the needs
of the 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.


-----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


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?
>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