A personal thanks for the invaluable customer input. I believe
that if we had more customers
coming forward with their detailed requirements it would help
break the current stalemate in the PMD
selections. This is the type of debate that I hoped to
stimulate in proposing that we should
re-address the objectives of the PMD’s; we need to clearly
resolve any ambiguity in the
objective statements in regards to application-space
media-distances and the usage of the word
"installed" to represent MMF fiber
As a supplier of Internet infrastructure product for Ethernet
I hear requests such as yours each day. I’ll paraphrase in
bullets here, borrowing from your e-mail.
----My reason for wanting MMF (a 10G interface over MMF) is
primarily cost simplicity, and
compatibility with my
current applications (technology and distances).
----Cost - overall cost for the total installation.
+++Labor – LAN installers familiar with multimode terminations
produce higher yields per unit time
+++Materials: Connectors, tools, patch cables, test equipment,
Laser/LED transceivers, etc...
Other customers of 10 Gb/s Ethernet addressing the reflector
and the task group have
voiced strong support for the inclusion of a low-cost
short-reach multimode fiber objective
even if it included the use of higher bandwidth MMF.
The task group responded to these
clearly stated customer requirements by including in
the current set of objectives a physical
layer specification for operation over 300 m of MMF.
Omission of the word "installed" was to
implicitly allow for the new higher bandwidth MMF fiber.
The usage of the word "installed" in the
100 meter objective was to identify the MMF with the MMF
currently specified in 802.3z.
In order to clearly identify the current implicit differences
in the MMF objective fiber types,
I offer the following definitions.
+++++Installed MMF – MMF as specified in 802.3z.
+++++MMF – Either installed MMF or the Next Generation MMF
currently proposed in both TIA and ISO. The development for
was supported in a Liaison letter issued from IEEE.
A low-cost serial 850 nm PMD option coupled with the
benefits of the higher bandwidth
300 meter multimode fiber solution will
addresses your requirements for cost, simplicity, and compatibility
with your current Ethernet (10 Mb/s-100
Mb/s-1 Gb/s) distances and for the 10 Gb/s Ethernet
distances. Additionally, the new MMF
coupled with the right PMD would allow for next generation
40 Gb/s Ethernet
The impact of media selection on technology deployment can be
The debate over driving single mode versus higher performance
new "in the building" LAN installations has the same flavor as
coax versus twisted-pair.
Before coming to CDT, I had worked at Digital Equipment
Corporation for almost 20 years.
DEC lost the Ethernet repeater business (coax) primarily due
to its slowness in responding
to the customer requirements for Ethernet over twisted-pair.
DEC said, "coax is technology
proof and will meet all of your long term application needs",
the customer said, "but my
reason for wanting twisted-pair is overall cost (installation,
testing, materials), simplicity, and
compatibility with my current applications (technology and
distances). The rest is history.
Chris Di Minico
Cable Design Technologies (CDT) Corporation
Director of Network Systems Technology
Phone: 800-422-9961 ext:333
----- Original Message -----
Sent: Thursday, July 27, 2000 12:31
Subject: RE: Equalization and benefits of
I also may be a bit confused. From a business
perspective I have this view.
My reason for wanting a 10G interface over MMF is primarily
cost and simplicity. Most of the servers I have installed are within
100M and most of the core and distribution switches are as well. If
there is a low-cost way to use some new-fangled media, then fine, but it seems
to me that improving ASIC technologies and economies of scale are the primary
downward factors in interface technologies.
If the MMF limit is 100M or less then the pain incurred for me
installing new MMF is relatively minor, as the distance is not that
large. This means the number of labor-intensive obstacles encountered
will be small. It is work and cost to be sure, but if the runs were for
200-500M+ then the labor costs would be *much* higher. However, I
believe the costs for the tooling, cables, certification gear and connectors
will increase if we choose some new radically different technology as the only
choice. In our experience the SFF connectors are not significantly less
in overall cost. (there are exceptions, but for the majority of them the
costs are quite similar to ST/SC) We still have *much* more difficulty
with the SFF installations due to primarily lack of available cables, field
termination components, and conversion cables. Also, there is the major
problem of field Zip<->Dual fiber MM adaptation to our installed ST/SC
I really do not care which technology is selected/specified,
but for the short-haul standard my primary goal is lowest overall cost for the
total installation. (Labor, connectors, tools, patch cables, test
equipment, Laser/LED transceivers, etc...) I care very little about
which form factor, mostly the cost and ease of use.
If such relatively simple Net things as the broken 10/100
Autoneg Phy and LX mode adaptation/conditioning cables are such a problem in
the wide acceptance of new technologies, then it seems like the KISS principle
should be a strong factor. I do not care how complicated it is
internally, but it needs to be simple for the end user.
I also seems to remember that the goal was 3X the cost of
1G. If the cable length limits are going to be <100M, then the
real-world-end-user-makes-the-comparison will be with 1000Base-TX copper, not
SX. This might make it much more difficult to complete the 3X cost
target unless there are *significant* savings in the
My engineering hat does not always agree with this, but then
it is business that pays the bills.
What do you good folks think?
Booth, Bradley [mailto:bradley.booth@xxxxxxxxx]
Sent: Wednesday, July 26, 2000 8:30
Subject: RE: Equalization and
benefits of Parallel Optics.
I have one question:
Which of our distance objectives is satisfied with parallel
It has been my interpretation that when we talked about 100m
base of MMF, that we were referring to
the MMF fiber currently available for
802.3z. Parallel optics does not operate over this installed
Or am I missing the point here?
From: ghiasi [SMTP:Ali.Ghiasi@xxxxxxxxxxx]
Tuesday, July 25, 2000 8:32 PM
Subject: RE: Equalization and
benefits of Parallel Optics.
> From: "Hakimi,
Sharam (Sharam)" <hakimi@xxxxxxxxxx>
> Subject: RE:
Equalization and benefits of Parallel Optics.
> Date: Tue, 25
Jul 2000 21:04:49 -0400
> MIME-Version: 1.0
> X-Info: [Un]Subscribe requests to
Although parallel fiber is technically an easier solution, the
> for support
of 850nm has been to consider the installed base, and
> users have to pull new fiber, IMHO, parallel fiber would not be
> the list and
most of installed base is single fiber.
I did not suggest
to pull any new fiber. Limit the shortwave
including parallel optics to the data center with 100 m radius.