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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.  


Petar Pepeljugoski
IBM Research
P.O.Box 218 (mail)
1101 Kitchawan Road, Rte. 134 (shipping)
Yorktown Heights, NY 10598

phone: (914)-945-3761
fax:        (914)-945-4134

Jonathan Jew <>

03/14/2008 01:32 PM
Please respond to

[802.3BA] Longer OM3 Reach Objective

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
J&M Consultants, Inc

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
USTAG representative to ISO/IEC JTC 1 SC25 WG3 data center standard adhoc