So I assumed similar to the items in your
first paragraph, as I believe many others did as well in the January discussion.
And when I stated “for this optical PHY” in my response below, it
is the power & complexity for this PHY’s application where many of
the concerns continue to exist wrt the incremental burden vs. the additional gain.
John
From: Ali Ghiasi [mailto:aghiasi@BROADCOM.COM]
Sent: Friday, March 14, 2008 5:00
PM
To:
STDS-802-3-HSSG@LISTSERV.IEEE.ORG
Subject: Re: [802.3BA] Longer OM3
Reach Objective
John
I do agree in applications that you have a gearbox in the module adding the
EDC to the host adds extra power and with little benefits for these
ports.
But assuming IEEE defines a PMA service interface XLAUI /CAUI as proposed by
http://www.ieee802.org/3/ba/public/mar08/latchman_01_0308.pdf
http://www.ieee802.org/3/ba/public/mar08/ganga_01_0308.pdf
then EDC or retimer will be associated to an specific PMD without burdening
all PMDs or adding complexity to the ASIC.
SFP+ is a great example we can follow and according to Ovum-RHK:will grow through
2011 at 202% CAGR for good reasons and you can listen to the webcast
http://lw.pennnet.com/webcast/display_webcast.cfm?id=529
SFP+ defines both limiting and linear interface. A limiting port can only
support SR and LR,
where a linear port can support SR, LR, LRM, and copper 10GSFP+Cu. For
nx10G PMD interface
we should follow the SFP+ winning model! 8.5Gig FC is also based on the
same model but
but with relax transmitter and a simple EDC for linear ports.
Thanks,
Ali
John Jaeger wrote:
"Previously when I stated the OM3 link can be extended to 300 m and with
increase link margin, the reply was there is no such application
requirements."
- not sure that is the way I remember the discussion going Ali. For me
anyways, it was centered on questioning the incremental power &
complexity/cost related to the required EDC for this optical PHY in order to
obtain the longer reach. And yes, there were a wide range of expressed
opinions on the application value of picking up some of the distribution
tails, but I never heard such a definitive statement of 'no application
requirement'.
John
-----Original Message-----
From: Ali Ghiasi [mailto:aghiasi@BROADCOM.COM]
Sent: Friday, March 14, 2008 3:41 PM
To: STDS-802-3-HSSG@LISTSERV.IEEE.ORG
Subject: Re: [802.3BA] Longer OM3 Reach Objective
Jonathan
In Jan 08 interim meeting I presented the following presentation
http://www.ieee802.org/3/ba/public/jan08/ghiasi_02_0108.pdf
and published in IEEE communication magazine:
http://dl.comsoc.org/cocoon/comsoc/servlets/GetPerson?id=10033162
which showed even with a 4G transmitter a 300 m OM3 link has one dB more
margin
using a simple EDC (Electronic Dispersion Compensation) compare to a
limiting link operating
over 100 m of OM3 fiber, similar to:
http://www.ieee802.org/3/ba/public/mar08/pepeljugoski_01_0308.pdf.
To meet IEEE objective to support copper cable for 10 operation, some
form of EDC
would be required. As long as the copper and the optical specifications
for linear
interface are not defined in orthogonal fashion, a port supporting
copper cable can greatly
benefit a port supporting linear optics and extend the reach to 300 m!
Previously when I stated the OM3 link can be extended to 300 m and with
increase link
margin, the reply was there is no such application requirements. It is
good to hear from
people like you.
Thanks,
Ali
Jonathan Jew wrote:
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