Re: [802.3_100GNGOPTX] Emerging new reach space
Dan,
While I understand that the discussion
is in the context of LR4, I'd like to comment on the 10x performance for
3x the cost. This model does not apply to the HPC application space any
more and I believe other applications will reach the same point soon. Since
the number of links continues to grow, bandwidth costs have already reached
critical point relative to the rest of the system and further increases
are not sustainable. If you look at the rest of the hardware elements of
a system (memory, cpu's, drives, I/O ports etc.) over the years their costs
have remained the same or declined while the performance has continued
its upward trend.
I think it is time for innovation, to
identify the costs and propose alternative solutions to address this issue,
like putting the modules deep inside, simplified packaging and integration.
The benefit will be not just the cost, but also power consumption and higher
density.
Regards,
Peter
Petar Pepeljugoski
IBM Research
P.O.Box 218 (mail)
1101 Kitchawan Road, Rte. 134 (shipping)
Yorktown Heights, NY 10598
e-mail: petarp@xxxxxxxxxx
phone: (914)-945-3761
fax: (914)-945-4134
From:
Daniel Dove <ddove@xxxxxxx>
To:
STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Date:
11/16/2011 02:55 PM
Subject:
Re: [802.3_100GNGOPTX]
Emerging new reach space
Hi Ali,
I like your first point.
Your last point was the first thing that
came to my mind. We really need to understand customer sensitivity to 8x
fiber runs of that length.
As for the cost modeling, today we use
10x performance for 3x the cost as a goal. Given the 2.5x performance relationship
between 100G and 40G, I would say that a reasonable goal should be 2.5x
the performance for equivalent cost.
As people consider ways to solve the 500m
to 1Km reach, they should be cognizant of the relative cost/performance
range to fit within, and consider customer sensitivity to fiber installation
costs/impacts as well.
Regards,
Dan
From: Ali Ghiasi <aghiasi@xxxxxxxxxxxx>
Reply-To: Ali Ghiasi <aghiasi@xxxxxxxxxxxx>
Date: Wed, 16 Nov 2011 09:03:16 -0800
To: 100G Group <STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
Jack
If there is another LR4 PMD out there the
best starting point would be 40Gbase-LR4, look at its cost structure, and
build a 40G/100G compatible PMD.
We also need to understand the cost difference
between parallel MR4 vs 40Gbase-LR4 (CWDM). The 40Gbase-LR4 cost
with time could be assumed
identical to the new 100G MR4 PMD. Having
this baseline cost then we can compare its cost with 100GBase-LR4 and parallel
MR4. The next step is to take
into account higher cable and connector
cost associated with parallel implementation then identify at what reach
it gets to parity with 100G (CWDM) or
100G (LAN-WDM).
In the mean time we need to get more direct
feedback from end users if the parallel SMF is even an acceptable solution
for reaches of 500-1000 m.
Thanks,
Ali
On Nov 15, 2011, at 8:41 PM, Jack Jewell
wrote:
Thanks for this input Chris.
I'm not "proposing" anything
here, rather trying to frame the challenge, so that we become better aligned
in how cost-aggressive we should be, which guides the technical approach.
As for names, "whatever works" :-) It would be nice to
have a (whatever)R4, be it nR4 or something else, and an english name to
go with it. The Structured Data Center (SDC) links you describe in your
Nov2011 presentation are what I am referencing, except for the restriction
to "duplex SMF." My input is based on use of any interconnection
medium that provides the overall lowest-cost, lowest-power solution, including
e.g. parallel SMF.
Cost comparisons are necessary, but I agree
tend to be dicey. Present 10GbE costs are much better defined than projected
100GbE NextGen costs, but there's no getting around having to estimate
NextGen costs, and specifying the comparison. Before the straw poll, I
got explicit clarification that "LR4" did NOT include mux/demux
IC's, and therefore did not refer to what is built today. My assumption
was a "fair" cost comparison between LR4 and (let's call it)nR4
- at similar stage of development and market maturity. A relevant stage
is during delivery of high volumes (prototype costs are of low relevance).
This does NOT imply same volumes. It wouldn't be fair to project ER costs
based on SR or copper volumes. I'm guessing these assumptions are mainstream
in this group. That would make the 25% cost target very aggressive, and
a 50% cost target probably sufficient to justify an optimized solution.
Power requirements are a part of the total cost of ownership, and should
be considered, but perhaps weren't.
The kernel of this discussion is whether
to pursue "optimized solutions" vs "restricted solutions."
LR4 was specified through great scrutiny and is expected to be a very successful
solution for 10km reach over duplex SMF. Interoperability with LR4 is obviously
desirable, but would a 1km-spec'd-down version of LR4 provide sufficient
cost/power savings over LR4 to justify a new PMD and product development?
Is there another duplex SMF solution that would provide sufficient cost/power
savings over LR4 to justify a new PMD and product development? If so, why
wouldn't it be essentially a 1km-spec'd-down version of LR4? There is wide
perception that SDC's will require costs/powers much lower than are expected
from LR4, so much lower that it's solution is a major topic in HSSG. So
far, it looks to me like an optimized solution is probably warranted. But
I'm not yet convinced of that, and don't see consensus on the issue in
the group, hence the discussion.
Cheers, Jack
From: Chris Cole <chris.cole@xxxxxxxxxxx>
Reply-To: Chris Cole <chris.cole@xxxxxxxxxxx>
Date: Tue, 15 Nov 2011 17:33:17 -0800
To: <STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_100GNGOPTX] Emerging new reach space
Hello Jack,
Nice historical perspective
on the new reach space.
Do I interpret your email
as proposing to call the new 150m to 1000m standard 100GE-MR4? J
One of the problems in using
today’s 100GE-LR4 cost as a comparison metric for new optics is that there
is at least an order of magnitude variation in the perception of what that
cost is. Given such a wide disparity in perception, 25% can either be impressive
or inadequate.
What I had proposed as reference baselines for making comparisons is 10GE-SR
(VCSEL based TX), 10GE-LR (DFB laser based TX) and 10GE-ER (EML based TX)
bit/sec cost. This not only allows us to make objective relative comparisons
but also to decide if the technology is suitable for wide spread adoption
by using rules of thumb like 10x the bandwidth (i.e. 100G) at 4x
the cost (i.e. 40% of 10GE-nR cost) at similar high volumes.
Using these reference baselines,
in order for the new reach space optics to be compelling, they must have
a cost structure that is referenced to a fraction of 10GE-SR (VCSEL based)
cost, NOT referenced to a fraction of 10GE-LR (DFB laser based) cost. Otherwise,
the argument can be made that 100GE-LR4 will get to a fraction of 10GE-LR
cost, at similar volumes, so why propose something new.
Chris
From: Jack Jewell [mailto:jack@xxxxxxxxxxxxxx]
Sent: Tuesday, November 15, 2011 3:06 PM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: [802.3_100GNGOPTX] Emerging new reach space
Following last week's meetings, I think
the following is relevant to frame our discussions of satisfying data center
needs for low-cost low-power interconnections over reaches in the roughly
150-1000m range. This is a "30,000ft view,"without getting overly
specific.
Throughout GbE, 10GbE, 100GbE and into
our discussions of 100GbE NextGenOptics, there have been 3 distinct spaces,
with solutions optimized for each: Copper, MMF, and SMF. With increasing
data rates, both copper and MMF specs focused on maintaining minimal cost,
and their reach lengths decreased. E.g. MMF reach was up to 550m in GbE,
then 300m in 10GbE (even shorter reach defined outside of IEEE), then 100-150m
in 100GbE. MMF reach for 100GbE NextGenOptics will be even shorter unless
electronics like EQ or FEC are included. Concurrently, MMF solutions have
become attractive over copper at shorter and shorter distances. Both copper
and MMF spaces have "literally" shrunk. In contrast, SMF solutions
have maintained a 10km reach (not worrying about the initial 5km spec in
GbE, or 40km solutions). To maintain the 10km reach, SMF solutions evolved
from FP lasers, to DFB lasers, to WDM with cooled DFB lasers. The 10km
solutions increasingly resemble longer-haul telecom solutions. There is
an increasing cost disparity between MMF and SMF solutions. This is an
observation, not a questioning of the reasons behind these trends. The
increasing cost disparity between MMF and SMF solutions is accompanied
by rapidly-growing data center needs for links longer than MMF can accommodate,
at costs less than 10km SMF can accommodate. This has the appearance of
the emergence of a new "reach space," which warrants its own
optimized solution. The emergence of the new reach space is the crux of
this discussion.
Last week, a straw poll showed heavy support
for "a PMD supporting a 500m reach at 25% the cost of 100GBASE-LR4"
(heavily favored over targets of 75% or 50% the cost of 100GBASE-LR4).
By heavily favoring the most aggressive low-cost target, this vote further
supports the need for an "optimized solution" for this reach
space. By "optimized solution" I mean one which is free from
constraints, e.g. interoperability with other solutions. Though interoperability
is desirable, an interoperable solution is unlikely to achieve the cost
target. In the 3 reach spaces discussed so far, there is NO interoperability
between copper/MMF, MMF/SMF, or copper/SMF. Copper, MMF and SMF are optimized
solutions. It will likely take an optimized solution to satisfy this "mid-reach"
space at the desired costs. To repeat: This has the appearance of the emergence
of a new "reach space," which warrants its own optimized solution.
Since the reach target lies between "short reach" and "long
reach," "mid reach" is a reasonable term
Without discussing specific technical solutions,
it is noteworthy that all 4 technical presentations last week for this
"mid-reach" space involved parallel SMF, which would not interoperate
with either 100GBASE-LR4, MMF, or copper. They would be optimized solutions,
and interest in their further work received the highest support in straw
polls. Given the high-density environment of datacenters, a solution for
the mid-reach space would have most impact if its operating power was sufficiently
low to be implemented in a form factor compatible with MMF and copper sockets.
Cheers, Jack