Re: Supporting Installed Fibre
Alan:
Thanks for re-stating the statistics. We have a goal of supporting 100 meters
on the installed MM fiber. We have a goal of supporting 300 meters on MM fiber.
I am not sure I want to start a debate on moving goal posts but I want everyone
to be crystal clear on the fact that these two goals as stated miss the
installed base of MM building backbones.
Although during the debate on distances, it was stated that we could change or
add goals later, apart from HP, I have seen little indication from the
optoelectronics companies that they are interested in supporting distances in
the ranges of 200 meters on installed MM fiber.
Customers are currently using 1000BASE-SX at the specified distance of 220
meters. They will expect to run 10 GbE on the same links. Not many of them will
want to pull a new "enhanced" MM fiber.
Bruce Tolley
Manager, Business Development, 3Com
Alan Flatman <a_flatman@xxxxxxxxxxxxxx> on 09/16/99 07:29:35 AM
Sent by: Alan Flatman <a_flatman@xxxxxxxxxxxxxx>
To: "IEEE 802.3 HSSG" <stds-802-3-hssg@xxxxxxxx>
cc: (Bruce Tolley/HQ/3Com)
Subject: Supporting Installed Fibre
I would like to offer some perspectives on supporting installed multimode
fibre links.
Firstly, let's remind ourselves of the statistics. I presented a survey of
installed fibre links in Montreal and compared this with existing data:
I found 25% of installed building backbone links within 100m
The maximum percentage found by other surveys for this distance was 35%
I would add approximately 3% to this figure to include in-range campus
links
I found 58% of installed building backbone links within 200m
The maximum percentage found by other surveys for this distance was 70%
I would add approximately 4% to this figure to include in-range campus
links
I found 88% of installed building backbone links within 300m
Other surveys found slightly less, so there was good correlation for 300m
I would add approximately 5% to this figure to include in-range campus
links
It's worth noting that cabling standards and installers treat horizontal
(generally copper) and backbone (generally fibre) cabling differently. The
horizontal medium is chosen and installed for generic use and for long life
(typically 10 years). The backbone medium is more application-dependent.
Standards for structured cabling have tried to specify optical fibre for
generic application but we do not believe that this is possible.
Consequently, we expect installed fibre backbone links to turnover more
frequently. As a consultant, I have been recommending a combination of MMF
and SMF in the backbone for some time.
Having said this, some organisations will not or cannot tolerate the
disruption associated with installing new fibre for 10GE. It will therefore
be useful to offer them a solution. Refer to the above statistics in making
this decision.
I tend to agree with Bruce Tolley that a 200m target for installed MMF is
much better than 100m. I also got the impression from the Montreal meeting
that 300m was possible but complex and expensive. I would like to hear more
from the optoelectronics industry before we move the goalposts.
Regards,
Alan Flatman