Chris,
I am referring to the discussions that
have focused on the use of FEC for enhancing reach in general, not necessarily as
a means to overcome issues with particular form factors. Several folks
have pointed out that because FEC lowers the operating BER threshold (Q factor)
it can be used to enhance power budgets and overcome noise and some bandwidth
limitations. In fact you have strongly advocated use of FEC yourself,
calling it the closest thing to a free lunch, as I recall.
Again, my inquiry into the parallelism between
copper and fiber regarding FEC was not meant to be form factor specific, except
to the extent that it might enhance reach with lower power dissipation in the
module than other methods, which could enable forms that would otherwise be ruled
out.
Paul
From: Chris Cole
[mailto:chris.cole@xxxxxxxxxxx]
Sent: Friday, January 13, 2012
9:15 PM
To: Kolesar,
Paul
Cc: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] -
MMF Ad Hoc - 17th Jan meeting timing
I am not sure I see how FEC comes
into play here.
The 25G QSFP+ connector is expected to have about as low loss
performance as any other 25G connector, so there is no power budget performance
gap to close. And other possible impairments like crosstalk are not improved by
FEC.
Jeff,
While I agree that universal port slots
are very attractive, density may be the overriding factor for server
access-optimized switches, where singe-mode optics would only be needed for
aggregated uplinks. If thermal management is the limiting issue, as
Chris points out in another reply to this thread, then density must be
sacrificed.
My main point in drawing parallels between
copper and fiber is for purposes of commonality with FEC. Given copper
has the lead, I am trying to determine what impact following that lead has on
fiber capability.
Paul
From: Jeffery Maki
[mailto:jmaki@xxxxxxxxxxx]
Sent: Friday, January 13, 2012
7:53 PM
To: Kolesar, Paul; STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_100GNGOPTX] -
MMF Ad Hoc - 17th Jan meeting timing
Paul,
This seems like a
good chance to reiterate why CXP is not most useful to the industry. It
is good for copper, just ok for parallel VCSEL optics, and a dead end for
anything more. QSFP will be good for copper and good for parallel VCSEL
optics, but a dead end for certain longer reach optics. Initially, it
will be a dead end for 100GBASE-LR4 but most are thinking implementation will
eventually reach the QSFP form factor. How long is the question.
My point is that
CFP4 is a form factor that achieves almost the same density as QSFP, and may
achieve the same integer number of ports for system companies on their line
cards, while at the same time being far more enabling.
It will be interesting
to see how system companies prioritize things. Regardless, QSFP will have
to interoperate with CFP4 when both ends are built according to the same
standard.
Jeff
From: Kolesar, Paul
[mailto:PKOLESAR@xxxxxxxxxxxxx]
Sent: Friday, January 13, 2012
5:44 PM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] -
MMF Ad Hoc - 17th Jan meeting timing
If copper fits in a QSFP+ then of course
it will also fit into larger forms, and it is not restricted. But for
access switch ports, which is where copper would be deployed, then higher
density is a big driver due to blade server density trends.
From: Chris Cole
[mailto:chris.cole@xxxxxxxxxxx]
Sent: Friday, January 13, 2012
7:18 PM
To: Kolesar, Paul
Cc: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] -
MMF Ad Hoc - 17th Jan meeting timing
What is the basis for your statement that 100G copper is restricted to
QSFP+?
John,
Thanks so much for this exploration, which
addresses just the sort of questions that have been puzzling me. In fact
I was wishing for a good comparison to SR10 just today. I see some good
parallels to Ali’s work emerging.
While it is not clear to me how much support
exists for FEC behind optical interfaces, it would be quite helpful if your
material could address how the addition or substitution of FEC affects the
numbers. If the outcome is that FEC allows QSFP+ form factor, then that
seems to enable common forms between fiber and copper media, which to me look
like a big advantage to the user and vendor, if not for near-term aggregation
switch ports at least for future server and access switch ports.
I also request the same clarification as
Jeff. If you need assistance with cabling cost particulars, I can
help. I have been analyzing cabling costs in my efforts to add such
analysis to the solution analyzer spreadsheet. A reasonable assumption
for the cost of SR4 cabling is ~40% of SR10 cabling cost.
Regards,
Paul
From: Jeffery Maki
[mailto:jmaki@xxxxxxxxxxx]
Sent: Friday, January 13, 2012
6:12 PM
To: John Petrilla; Jonathan King; STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx;
a_flatman@xxxxxxxxxxxxx; Amezcua, A. (Adrian); Anslow, Peter; Anthony Torza; Bernstein, Gary; Brad Booth; Daniel Dove; Ephrem Wu; Gary Nicholl (gnicholl); Harry Fu; Jack Jewell; Keith Nellis; Kolesar, Paul; Lian Zhao; Martin Gilpatric; mike.dudek@xxxxxxxxxx; mnowell@xxxxxxxxx; Oren Sela; Piers Dawe; Rick.Pimpinella@xxxxxxxxxxx;
Robert Coenen;
ryan.latchman@xxxxxxxxxxxxx; Scott Kipp; Shmuel Levy; Sudeep Bhoja; Vipul Bhatt
Subject: RE: [802.3_100GNGOPTX] -
MMF Ad Hoc - 17th Jan meeting timing
John,
Great effort.
On your slide 2, can
you make clear whether your conclusion includes the MMF cabling cost?
Jeff
From: John Petrilla
[mailto:john.petrilla@xxxxxxxxxxxxx]
Sent: Friday, January 13, 2012
3:03 PM
To: Jonathan King; STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx;
a_flatman@xxxxxxxxxxxxx; Amezcua, A. (Adrian); Anslow, Peter; Anthony Torza; Bernstein, Gary; Brad Booth; Daniel Dove; Ephrem Wu; Gary Nicholl (gnicholl); Harry Fu; Jack Jewell; Jeffery Maki; Keith Nellis; Kolesar, Paul; Lian Zhao; Martin Gilpatric; mike.dudek@xxxxxxxxxx; mnowell@xxxxxxxxx; Oren Sela; Piers Dawe; Rick.Pimpinella@xxxxxxxxxxx;
Robert Coenen;
ryan.latchman@xxxxxxxxxxxxx; Scott Kipp; Shmuel Levy; Sudeep Bhoja; Vipul Bhatt
Subject: RE: [802.3_100GNGOPTX] -
MMF Ad Hoc - 17th Jan meeting timing
Hello Jonathan
Attached is a draft
presentation prepared for the Newport Beach
meeting. Although I’m not sure of my schedule/availability for
Tuesday morning, I would appreciate feedback from any who care to offer some.
Have MMF ad hoc
conference contact details for Tuesday been distributed?
Regards,
John
Dear all
A reminder
that there will be an MMF ad hoc meeting on Tuesday 17th Jan
2012, from 8am to 10.30 am PCT, in order to minimize the overlap with a
concurrent OIF meeting.
If you have material
to present, please let me know before hand.
Thanks
Jonathan
+1 408 368 3071
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