Frank,
With all due respect I cannot say that I
have observed the trend you are speaking of. In fact, several of my own
customers have dropped EDC and moved toward simpler limiting type ports. There
are also simpler linear solutions getting traction that do the job for
everything except LRM reaches.
I also would be interested in
understanding what is implied by minimum extra power consumption. A simple
survey of available IC’s shows ~ 200 mW (absolute best case, comparing 0.065
um apples with 0.13 um oranges, otherwise a fair comparison is probably 400 mW)
per SFP+ channel extra for chips with EDC, compared to chips without. 200 mW
per port for a 48 port switch is close to 10 Watt. And you will have more than
one pizza box in a datacenter, I am sure.
Now that’s assuming LRM type EDC, so
with a light version that supposedly we can now do with I know you guys are
saying it won’t be as much, but then the burden is on you folks to
demonstrate this. Because otherwise the concept ingrained in a lot of folks
minds, including myself is EDC = lots of power
I do agree with Ali though, to have
several interfaces, one XFI-like, and some SFI and KR like ones as well for
other PMDs.
Best
Gourgen Oganessyan
Strategic Marketing Manager
Quellan Inc.
Phone: (408)-625-2196
(voicemail)
(630)-802-0574
(cell)
Fax: (630)-364-5724
e-mail: gourgen@quellan.com
From: Frank Chang
[mailto:ychang@VITESSE.COM]
Sent: Friday, March 14, 2008 10:44
PM
To:
STDS-802-3-HSSG@LISTSERV.IEEE.ORG
Subject: 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.
From: Petar
Pepeljugoski [mailto:petarp@us.ibm.com]
Sent: Friday, March 14, 2008 7:20
PM
To: Frank Chang
Cc:
STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [802.3BA] Longer OM3
Reach Objective
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
|
Please
respond to
Frank Chang <ychang@VITESSE.COM>
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STDS-802-3-HSSG@LISTSERV.IEEE.ORG
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cc
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Subject
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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
|
Please
respond to
jew@j-and-m.com
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STDS-802-3-HSSG@LISTSERV.IEEE.ORG
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cc
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Subject
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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