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FW: Why 10xGbE may be a bigger market than 1xGbE - a customer's perspective

To: Bill ST Arnaud/CANARIE

From: David Dolfi/Hewlett-Packard

Subject: DWDM in "gopher" fiber

Date: 5/5/99

Your message to the GbE high speed study group (below) was forwarded
to me by one of my engineers.  In it you make the point that wide WDM
(WWDM) might not work on "gopher bait" fiber.  As an advocate of WWDM 
for 10 Gb Ethernet, I would like to understand why this is the case.
I would think that fiber which is damaged or overspliced would work
better at the lower baud rate (3.125 GBd) of 4 channel WWDM than at
the 4X higher baud rate (12.5 GBd) of serial 10 Gb Ethernet.

Please remember when responding  that the 4 channel WWDM we are advocating 
for 10 Gb Ethernet has the following properties:

1. The targeted link lengths are 10 km or less, so no EDFA's are
2. The 4 wavelengths we are using are in the 1300 nm region of the
spectrum (NOT 1550) and have channel spacings of 15-20 nm.

Finally, I would think that fiber which is overspliced and/or
damaged would have a high loss, and I'm puzzled why a multi-level
coding scheme (which typically requires a high S/N ratio) would be
suitable for such fiber while WWDM would not.

Am I missing the point here?  Please respond!

Dave Dolfi
email: dolfi@xxxxxxxxxx

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To: "DOLFI, DAVE (HP-PaloAlto,unix3)" <dolfi@xxxxxxxxxx>,
        "LEMOFF, BRIAN (HP-PaloAlto,unix3)" <lemoff@xxxxxxxxxx>
Subject: FW: Why 10xGbE may be a bigger market than 1xGbE - a customer's p
Date: Wed, 5 May 1999 16:02:43 -0700
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Dave and Brian,
Here is a message against WWDM...


-----Original Message-----
From: Bill St. Arnaud [] 
Sent: Wednesday, May 05, 1999 2:44 PM
To: David_Law@xxxxxxxx; stds-802-3-hssg@xxxxxxxx
Subject: Why 10xGbE may be a bigger market than 1xGbE - a customer's


I have been watching the 802.3 high speed study group developments with
interest.  This is a technology development we have been pushing the vendors
for almost 2 years now.  We are aware of a number of proprietary solutions
that have been promised to us later this year.  So I hope the study group
moves quickly to develop a common standard.

We are deploying an optical Internet across Canada  We are
currently using POS, but we have identified a lot of deficiencies with POS
and we believe that "simplex, auto-negotiation 10xGbE" might be a better
solution for medium/long range WANs up to 1000 km.  Here are the reasons:

1.  There is a lot of "gopher bait" fiber in the ground that the carriers
can't use for traditional SONET networks. Gopher bait fiber is usually fiber
that has been damaged, or has too many splices and will not support OC-48 or
OC-192 clock rates. As well, a lot of carriers in the 80s deployed ZDSF
fiber that was optimized for TDM traffic and will not support WDM. So these
carriers are leaving this stuff in the ground and are now deploying NZDSF
fiber that can support DWDM

Ad hoc estimates we have heard is that about 30% of the installed fiber base
is gopher bait.

We believe that auto -negotiation 10xGbE would be the perfect protocol for
such a fiber, even if we use inefficient 8b/10b coding.

2. With auto-negotiation we could use the gopher bait fiber with long
repeater spacing, perhaps starting off with clock rates at less than 1xGbE.
As demand for bandwidth increases we could install intermediary transceivers
(and/or EDFA or PDFA) to support a faster clock rate.  It allows us to have
small upfront capital cost and incrementally grow the network bandwidth as
demand warrants rather than installing an expensive up front OC-192 system
and highly conditioned fiber.

Auto-negotiation might also compensate for PMD changes as it varies
throughout the day.

3. A practical as possible we believe that 10xGbE should be made a simplex
protocol.  The Internet, itself is fundamentally a unicast/simplex network.
In the Internet today there is significant asymmetric traffic loads between
the Tx/Rx paths -in some case the asymmetric variance can be 16:1.  As such
we are deploying links where they may be more Tx paths than Rx paths.  Since
there is no guarantee that there will an Rx for every Tx, as much as
possible auto-negotiation protocols, laser safety signaling should be done
at the IP layer.  Maybe the PHY should be IP addressable and managed at the
IP layer?

4. We would hope that the study group would also look at some of the
proposed SDL protocols as increasingly many optical links will run on data
and bit rate transparent networks. The overhead associated with CRC, etc is
not necessary any more.

5. We believe that either a serial TDM, or multi-level signal protocol would
be the best as WWDM might not work very well on gopher bait fiber

Looking forward to see the results of your deliberations.  We are in the
process of setting up a 10xGbe 50 km and 500km test facility for those who
might be interested in experimenting with some of the 10xGbE concepts

Also, we have some background papers for those who are interested in our
program on optical Internet technologies


Bill St Arnaud
Director Network Projects



> -----Original Message-----
> From: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx]On Behalf Of
> David_Law@xxxxxxxx
> Sent: Wednesday, May 05, 1999 11:28 AM
> To: stds-802-3-hssg@xxxxxxxx
> Subject: Higher Speed Study Group e-mail reflector archive
> All,
> After discussions with the IEEE it has been agreed that the
> reflector archive no
> longer needs to be in a password protected area of the web site.
> Due to this the
> archive has been moved to a new URL:-
> Please update any boookmarks you may have of the old location.
> Thanks,
>    David Law
> |=========================================|
> | David Law                               |
> | Vice-Chair IEEE 802.3                   |
> | 3Com                                    |
> | 3Com Centre,                            |
> | Boundary Way,                           |
> | Hemel Hempstead,                        |
> | Hertfordshire, HP2 7YU,                 |
> | United Kingdom                          |
> | Phone: +44 1442 438060                  |
> | Fax:   +44 1442 438333                  |
> | E-Mail: David_Law@xxxxxxxx              |
> |=========================================|

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