Re: [HSSG] Reach Objectives
Matt,
In consideration of parallel fiber SM
solutions, we need to recognize that the cost of parallel cabling, whether
MM or SM, has a higher "start-up" cost, driven by the cost
of array terminations. While it will be true that the cost per meter
will be lower for SM cabling, when you combine the start-up cost for a
short structured SM cabling channel (i.e. two array patch cords on the
ends of a array-terminated cable) with the additional cost of SM parallel
optics, the cost advantage will belong to MM. This is true because
not only will the SM parallel optics cost more, so will the SM array-terminated
cabling. The differential will shrink as the channel length grows,
but will probably not become advantageous for parallel SM until the channel
length exceeds the MM target length. Beyond that length the parallel
SM solution steps into a comparison with other SM alternatives such as
WDM, where it may make sense for a certain distance range.
One way to cut the start-up cost for
parallel solutions is to reduce the number of strands needed. When
thinking parallel transmission at 100G, many probably assume use of 12
fibers in each direction, meaning two array connections at the equipment,
one for the Tx and the other for the Rx. But it is possible to cut
the number of strands in half using the simplest of WDM concepts. For
example, by using only two wavelengths, one can build a 10-channel transceiver
that needs only five fibers in each direction. This not only reduces
the cabling cost by half, but also reduces the transmit/receive modules
by half as well (i.e. separate transmit and receive modules become one
transceiver). In the trade, one increases the optical complexity
of the modules. Depending on the relative costs of the items in trade,
the break even channel length can be anywhere from near zero (if the added
module complexity costs the user no more than that of two array patch cords,
a short array cable, and the package cost of one module) to above the target
objective distance. If the former, then this concept deserves to
be taken seriously. If the latter, then it lacks sufficient merit
to warrant further work. But for me, the answer lies in the cost
details. To understand this better the trade-off should be explored.
So I would encourage us to think not
purely in terms of parallel or WDM, but also for cases where combinations
of the two may make the best choice.
Regards,
Paul Kolesar
CommScope Enterprise® Solutions
1300 East Lookout Drive
Richardson, TX 75082
Phone: 972.792.3155
Fax: 972.792.3111
eMail: pkolesar@xxxxxxxxxxxxx
| Petar Pepeljugoski <petarp@xxxxxxxxxx>
08/22/2006 01:55 PM
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Please respond to
Petar Pepeljugoski <petarp@xxxxxxxxxx> |
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| Re: [HSSG] Reach Objectives |
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Matt,
I am open to the idea of making a specification for 1300nm or 1550nm parallel
links, although I doubt they will be competitive. The decision should be
made based on feasibility/costs and prospects of having products by the
time the standard is adopted.
We have given the benefit of the doubt in the past (example 802.3ae specs
for 1300nm friendly to VCSELs, although no one has shipped them yet).
Regards,
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
| "Matt Traverso"
<matt.traverso@xxxxxxxxx>
08/22/2006 02:46 PM
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To
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| Re: [HSSG] Reach Objectives |
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Hi Petar, John,
Since the OM3 fiber we are discussing would primarily be parallel, is there
merit in defining an OM3 PMD versus specifying a parallel SMF based
PMD?
My assumption is that in both cases the data center in question would be
pulling new fiber. If my assumption is true, then we should not limit
our consideration to OM3,but should also look at SMF. For example
SMF would allow for the extension to greater distances more simply.
There may indeed be merit in defining the data center PMD to be OM3 based,
but my opinion is that we should not jump to conclusions.
thanks
--Matt Traverso
Opnext, Inc.
mtraverso@xxxxxxxxxx
Note - I sent this from a personal account to avoid an automated statement
from my IT dept which contains phrases that would likely be considered
"unfriendly" to the reflector.
On 8/22/06, Petar Pepeljugoski <petarp@xxxxxxxxxx>
wrote:
Brad,
I agree with you. And the breakpoints vary from solution to solution.
Let's consider the following two examples:
1. N ch. x 10 Gb/s over OM3 fiber at 50m, and at 100m, there is very little
difference in the specs, so the cost will most likely not be affected.
2. M ch. x 17 Gb/s (or 20 gb/s) over OM3, there will be much larger difference
between 50m and 100m and there might be cost premium.
This will depend on the expected yield distribution and how sensitive is
to changes in the specs. So, we will need to carefully tread and not become
prisoners to the reach objectives, but rather optimize the cost.
From our perspective, there are distances up to 150m, but the largest distances
are not so common, so that is why I proposed the 100m.
Whatever is not covered by the 0-100m, should be covered by the next PMD
(most likely SMF based). That will reduce the cost by giving it additional
volume, while the short distance on the MMF will drive the cost by increasing
the yield.
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
Excuse my ignorance, but why? When 10G started, this was an important
debate. If they had stuck with the number of PMDs in 802.3z, then
there would have only been two PMDs. The study group needs to define
the markets that it wants to satisfy, and only then when the study group
becomes a task force can the group decide on the actual number of PMDs
required.
Thanks,
Brad
From: Drew Perkins [mailto:dperkins@xxxxxxxxxxxx]
Sent: Tuesday, August 22, 2006 10:45 AM
To: Brad Booth; STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: RE: [HSSG] Reach Objectives
I have a simple proposal to save everyone a lot of time. Let's make the
baseline plan to stick with exactly the same number of PMDs with exactly
the same reaches as 10GbE. They have all been developed to fit someone's
requirements. We should have a very high hurdle to eliminate any of these
or add to them.
Drew
_____________________________
Drew Perkins
Chief Technology Officer
Infinera Corporation
1322 Bordeaux Drive
Sunnyvale, CA 94089
Phone: 408-572-5308
Cell: 408-666-1686
Fax: 408-904-4644
Email: dperkins@xxxxxxxxxxxx
WWW : http://www.infinera.com
_____________________________
From: Brad Booth [mailto:bbooth@xxxxxxxxxxxxx]
Sent: Tuesday, August 22, 2006 10:19 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] Reach Objectives
The 10km vs. 2km debate occurred in 802.3ae. It was determined that
the solution for 2km was virtually the same as that for 10km; therefore,
the task force felt it would be better to select only one of those reaches
and 10km was it. If there is a desire for 2km and 10km reaches in
HSSG, then in my humble opinion, those wishing to support will need to
bring justification forward as to why the study group should consider possibly
increasing the number of PHYs.
Cheers,
Brad
From: Frank Chang [mailto:ychang@xxxxxxxxxxx]
Sent: Tuesday, August 22, 2006 9:19 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] Reach Objectives
John/Petar;
I agree datacenter for up to 100m. How about 10GigE LR disctance (10km)
or campus 2km discussed earlier?
Frank
-----Original Message-----
From: Petar Pepeljugoski [mailto:petarp@xxxxxxxxxx]
Sent: Tuesday, August 22, 2006 6:02 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] Reach Objectives
John,
I believe that the Data Center distances should be 100m and 300m.
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
All,
We have had some conversation on the reflector regarding reach objectives.
Summarizing what has been discussed on the reflector I see the following
–
Reach Objectives
Long-Haul --> 100+ km
Metro --> 10+ km
Data Center --> 50m & 300m
Data Center Reach Segregation
Intra-rack
Inter-rack
Horizontal runs
Vertical risers
Use this data to identify a single low-cost solution that would address
a couple of the reach objectives
Other Areas
During the course of the CFI there were individuals who wanted Backplane
Applications kept in for consideration, but I have not heard any further
input in this area. Are there still individuals who wish to propose
Backplane as an objective?
John