Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

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:
006201c88622$d04e1f90$1f12fea9@infinera.com" type="cite"> 
"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

  
    



  

begin:vcard
fn:Ali Ghiasi
n:Ghiasi;Ali
org:Broadcom;HSIP
adr;dom:;;3151 Zanker Road;San Jose;CA;95014
email;internet:aghiasi@broadcom.com
title:Chief Architect
tel;work:(408)922-7423
tel;cell:(949)290-8103
version:2.1
end:vcard