Depending on the sources of link
statistics, 100m OM3 reach objective actually covers from 70% to 90% of the
links, so we are talking about that 100m isnot even close to
95% coverage.
Regards
Frank
From: Petar Pepeljugoski
[mailto:petarp@US.IBM.COM] Sent: Friday, March 14, 2008 5:09
PM To: STDS-802-3-HSSG@listserv.ieee.org Subject: Re:
[802.3BA] Longer OM3 Reach Objective
Hello Jonathan,
While I am
sympathetic with your view of the objectives, I disagree and oppose changing the
current reach objective of 100m over OM3 fiber.
From my previous standards experience, I believe that all
the difficulties arise in the last 0.5 dB or 1dB of the power budget (as well as
jitter budget). It is worthwhile to ask module vendors how much would their
yield improve if they are given 0.5 or 1 dB. It is responsible for most yield
hits, making products much more expensive. I believe that selecting specifications that penalize 95% of the
customers to benefit 5% is a wrong design point.
You make another point - that larger data centers have
higher bandwidth needs. While it is true that the bandwidth needs increase, you
fail to mention is that the distance needs today are less than on previous
server generations, since the processing power today is much more densely packed
than before.
I believe that 100m is
more than sufficient to address our customers' needs.
Sincerely.
Petar Pepeljugoski IBM Research P.O.Box 218
(mail) 1101 Kitchawan Road, Rte. 134 (shipping) Yorktown Heights, NY
10598
I
am a consultant with over 25 years experience in data
center infrastructure design and data center relocations including in
excess of 50 data centers totaling 2 million+ sq ft. I am currently
engaged in data center projects for one of the two top credit card processing
firms and one of the two top computer manufacturers.
I'm concerned
about the 100m OM3 reach objective, as it does not cover an adequate number
(>95%) of backbone (access-to-distribution and distribution-to-core
switch) channels for most of my clients' data centers.
Based on a review of my current and
past projects, I expect that a 150m or larger reach objective would be more
suitable. It appears that some of the data presented by others to the
task force, such as Alan Flatman's Data Centre Link Survey supports my
impression.
There is a pretty strong correlation between the size of my
clients' data centers and the early adoption of new technologies such as
higher speed LAN connectivity. It also stands to reason that larger
data centers have higher bandwidth needs, particularly at the network
core.
I strongly encourage you to consider a longer OM3 reach objective
than 100m.
Jonathan Jew President J&M Consultants,
Inc jew@j-and-m.com
co-chair BICSI data center standards
committee vice-chair TIA TR-42.6 telecom administration
subcommittee vice-chair TIA TR-42.1.1 data center working group (during
development of TIA-942) USTAG representative to ISO/IEC JTC 1 SC25 WG3
data center standard adhoc