Marcus,
Thank you for
elaborating – this is indeed what I meant. As for the increased
complexity increasing the cost, I find this a bit of a red herring. It
basically implies some extra design time for the IC that would do the
physical-layer aggregation. As you mention, much of this work will have to be
done anyway, to allow for member failure, deskew (synchronization), etc. Making
things flexible would add some extra work. However, I’m not convinced it
would make all that much difference relative to the NRE and overall design
costs associated with the IC development. Any difference would, of course, be
amortized over the number of ICs shipped. We have to keep in mind that for a
high-volume product, the optics cost outweighs the IC cost. If the product is
not high volume, then both optics and IC costs per unit will be high in any
case, particularly when you amortize development costs.
Mike, as for what PMDs
this would work over, the answer is – any. They could be wavelengths,
different fibers, or some mix of these. Also, there’s no need for the
various PMDs to be bundled into a single package (although that is certainly
one implementation option).
The bottom line is,
the PMDs could stay the same as the ones we use now. The difference would lie
behind those PMDs, in the IC world.
I hope this answers the
questions.
Best wishes,
Jugnu
From: Marcus Duelk [mailto:duelk@xxxxxxxxxx]
Sent: Monday, August 07, 2006 7:32
PM
To:
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] Topics for
Consideration
Mike,
good questions. I think that there is a general dilemma of making the
choice between a simple lower-cost and a more flexible, complex and
higher-cost solution. Probably one solution is more justified in certain
networks (e.g. LAN/SAN) while the other is more suitable for other
networks (e.g. MAN/WAN).
I think Jugnu's idea was to eventually decouple the service rate from
the physical line rate by using physical layer aggregation similar to VCAT.
If you work with parallel PHYs over a WDM MAN/WAN you probably
have to define VCAT features anyway (e.g. differential delay compensation,
protection against loss of members, etc.). In that scenario, you wouldn't
necessarily have to define what the final service rate is, similar to a virtual
concatenated group which consists of N bandwidth 'units' (e.g. STS-1's).
Today's VCAT scales up to 256 members for one group. If you define
something like that for Ethernet and allow your 'bandwidth units' to be 1GbE
or 10GbE then that would scale to 256 Gb/s or 2.56 Tb/s max. service rate.
These things are done nowadays for overlay networks (over TDM,
or OTN), but in principle you could also use other metrics.
Marcus
Mike Bennett wrote:
Jugnu,
OJHA,JUGNU wrote:
Mike,
It seems more reasonable to me to consider
finally decoupling the physical pipe size from the rigid hierarchy used in the
past. Why not simply define a scalable interface that allows inverse
multiplexing (physical layer aggregation – not the type of aggregation
you have described, which sounds like the current LAG) of an arbitrary (within
some bounds, obviously) number of physical channels (10G) into a single logical
link? The SONET/SDH and Digital Wrapper/OTN world already has mechanisms
to do this (VCAT, LCAS), and dynamically to boot.
This would provide a much more flexible,
scalable solution to customers.
On the surface, it seems to me that with flexibility
comes complexity which leads to higher cost. It's also not clear to me
how the physical layer aggregation you propose translates to a port on a
switch. Would I have to buy an N x 10G transceiver? Would it be a
WDM-like transceiver? Would this work with a single fiber-pair or
multi-strand? What would the relative incremental cost be (in
percentages, non monetary units) to scale up? Also, are you
proposing that this would scale beyond 100G? If so, how far? You
mention boundaries - I'm curious what you think the upper bound would be.
I hope you're planning to present something at the interim as it would
help me understand what you're really proposing and how that compares to other
ideas.
Regards,
Mike
In particular, it would allow them to grow
capacity on any given link as needed, instead of having to install 10x10G
channels up front. Further, when they hit 100G, they wouldn’t be
stuck until some other solution is defined – they could continue to grow.
Respectfully,
Jugnu Ojha
Avago Technologies
John, et al.,
>During our first meeting, I anticipate spending a lot
of time focusing on objectives. At the >closing plenary I
highlighted two issues / objectives that the SG would have to consider:
>
> Tradition of
10x leap in speed
I think the speed
increase has to be 10x. The standards development process will take at
least 3.5 to 4 years to complete. Anything less than 100G will force
people who are currently aggregating 10G links to continue to use aggregation,
only using fewer higher-speed, and more expensive links. End users
prefer using a single link over aggregating physical-layer links into a logical
link because of the complications that come with aggregation. The data in
the CFI presentation was just a sample of cases in which network operators
we're aggregating 10G links to accommodate the demand on their networks.
There will be many more by 2011 (when I expect there would be 'real' products
on the market).
> Multiple
Reach Targets
>
It was also presented that the focus of this effort wasn’t for a desktop
application, and >that the cost model needs to be considered.
I believe we need to adjust the cost model in such a way that it is aligned
with the ecosystem. It is unreasonable, in my opinion, to expect a 10x/3x
model to apply to systems designed for wide-area/metro-area networks. I
also think it's short-sighted to ignore the rest of the ecosystem and develop
Ethernet only in the part of the ecosystem where the original cost model
applies.
Regards,
Mike
--
Michael J. Bennett
Sr. Network Engineer
LBLnet Services Group
Lawrence Berkeley Laboratory
Tel. 510.486.7913
--
Michael J. Bennett
Sr. Network Engineer
LBLnet Services Group
Lawrence Berkeley Laboratory
Tel. 510.486.7913
--
___________________________
Marcus Duelk
Bell Labs / Lucent Technologies
Data Optical Networks Research
Crawford Hill HOH R-237
791 Holmdel-Keyport Road
Holmdel, NJ 07733, USA
fon +1 (732) 888-7086
fax +1 (732) 888-7074