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John,
In some respects, I think that (A) and (B) in your
description might be good candidates to tackle in separate projects
(PARs).
Let me comment on proposal (B) first:
I would characterize this as a study of "Multiple Lane
Approaches". Here, there are a number of questions to be
answered:
1) Is the number of "lanes" fixed or
variable?
2) Can the interface operate at reduced bandwidth in
the presence of failure of individual lanes?
3) What is the network architecture governing the
multi-lane interconnection? Are multiple lanes carried over a single span only,
or can the lanes be carried independently across a network and only reaggregated
at the endpoints? (attractive feature here: not necessary to build the new
interface on every network element along a path between ultra-high rate
endpoints to provide an ultra-high rate service. Network elements transporting
individual lanes can be blissfully unaware that that lane is part of a larger
aggregate). This network architecture has an impact on the differential delay
that may need to be accommodated across the lanes when they are
re-aggregated.
4) Are the individual lanes carried over existing or new
physical interfaces?
5) Can we learn from or reuse the capabilities from ITU-T
Virtual Concatenation and LCAS to provide this kind of physical layer
aggregation?
Back to proposal (A), I think that even those of us who
think that (B) is an important problem to solve do not believe that 10G is the
highest rate we will ever have for serial transport. So the way I would like to
see (A) approached is to study what the next potential serial interface rate
above 10G should be and what its characteristics are. Here, we could study 100G,
40G or other rates that provide a suitable evolution and are supported by the
technology.
40G has some attractive characteristics since it could
reuse components from transport interfaces at the same rate (SONET OC-768, SDH
STM-256, or OTN OTU-3). Note that in one sense, we already have WAN PHY type
interfaces at 40G if you consider Ethernet frames mapped via GFP-F into SONET
OC-768c, SDH VC4-256c, or OTN OPU3.
Of course even 40G is not the highest rate interface that
we will ever build, so even if 40G is considered to be an evolutionary step
along the path of increasing bandwidth, it is worth studying what the next
serial rate should be above 40G.
Regards,
Steve
All,
In regards to proposed MAC data
rates, I have seen two basic proposals
Proposal A) 100
Gb/s
Proposal B) Scalable
Solution
Proposal A supports the
traditional 10x increase in speed.
Proposal B, as presently
discussed, is unbounded. (The following are only my observations of
statements made on the reflector by others) The lowest limit proposed
was a 4x10 approach for 40 Gb/s. No upper limits have been
proposed. It has been suggested that this approach should use existing
PMDs, but there have been also been comments regarding use of 10G, 25G, and
40G lambdas, but that carriers would want to leverage their
existing DWDM layer, which mean baudrate in the 9.95-12.5 Gig. Consuming
wavelengths has been brought up as a possible concern. It was also
suggested that the greatest bandwidth demands are on VSR links < 50m and
that the longer reach (>10km) may be able to live with 4x10G. (Data
in support of these observations that could be used to guide the creation of
objectives would be welcome.)
An objective for Proposal A could
be similar to what was done for 10 GbE– Support a speed of 100.000 Gb/s at the
MAC/PLS service interface.
For Proposal B, given its current
unbounded nature and multiple discussion points, I am not sure what would be
proposed. I am looking to the advocates of this proposal to provide some
verbiage to the reflector for discussion. Using the objective above as a
basis: Support a speed greater than 10.000 Gb/s at the MAC/PLS service
interface, would create too broad an objective.
Also for both proposals what are
people’s thoughts on an objective that would specify an optional Media
Independent Interface (MII)?
John
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