Re: [802.3BA] Longer OM3 Reach Objective
Petar;
I donot disagree with your viewpoint, but my
thinking this argument is really an application call to the
industry.
If you hint that the significant more
power is brought up by required EDC circuit, then I disagree with
that. As we know from various mtg discussions, we are not talking about the
complicate circuitry such as the one for LRM, which seems unnecessarily overkill
for such case. It should be very simple type of equalization
circuit, its extra power consumption could still remain minimum, while
could be well compensated by extra perf. margin, much better
yield, in addition to the flexibility and simplicity in system
adjustment because of implementing
it.
Also I donot
think we are in a position trying to avoid the use of EDC. The
trend shows that it could possibly become one standard feature in
PHY IC offering. Take the SFP+ as an example, even the SR version is
taking its advantage for extra margin, system robustness, less BOM etc
etc. This could be beyond the question regarding the
incremental power & complexity/cost related to that.
Regards
Frank
Frank,
You are missing my point. Even the best case stat, no
matter how you twist it in your favor, is based on distances from yesterday. New
servers are much smaller, require shorter interconnect distances. I wish you
could come to see the room where current #8 on the top500 list of
supercomputers is (Rpeak 114 GFlops), maybe you'll understand then.
Instead of trying to design something that
uses more power and goes unnecessarilly longer distances, we should focus our
effort towards designing energy efficient, small footprint, cost effective
modules.
Regards,
Petar Pepeljugoski
IBM Research
P.O.Box 218
(mail)
1101 Kitchawan Road, Rte. 134 (shipping)
Yorktown Heights, NY
10598
e-mail: petarp@us.ibm.com
phone: (914)-945-3761
fax:
(914)-945-4134
| Frank Chang
<ychang@VITESSE.COM>
03/14/2008 09:23 PM
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Frank Chang
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| Re: [802.3BA] Longer OM3 Reach
Objective |
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Petar;
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
e-mail:
petarp@us.ibm.com
phone: (914)-945-3761
fax:
(914)-945-4134
| Jonathan Jew
<jew@j-and-m.com>
03/14/2008 01:32 PM
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jew@j-and-m.com |
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| [802.3BA] Longer OM3 Reach
Objective |
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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