Re: [HSSG] MAC Data Rate of Operation Objective
Colleagues-
While multi-hop laneing might be an interesting concept,
it would be out of scope for 802.3
(it MIGHT be in scope for 802.1, but I don't think so)
It would violate our traditional layering model to such an extent that I
suspect it would break a LOT of other stuff.
Geoff
At 05:07 PM 8/14/2006 , OJHA,JUGNU wrote:
Steve,
Many of your questions are answered in messages just exchanged between
Geoff Thompson and me. To address some of the others:
A multi-hop solution without realignment/reassembly sounds
difficult, if not impossible:
1) How would intermediate nodes read the
destination MAC address?
2) The inter-channel skew would be effectively unbounded.
The question of what channel rates higher than 10G to use is related to
the question of mixing and matching lanes of differing speeds. For
starters, I think we should apply some judgment on the latter issue i.e.,
would anyone really want to mix 10G and 1G lanes to build a really fat
pipe? If we re talking about a pipe of 20-100 G or more, do
additional 1G increments really add any value? Regarding lane
speeds higher than 10G, the question becomes, Can we define aggregation
of lanes whose speeds are as yet unknown, or do we have to make a
decision today on speeds (and hence, technologies) that don t exist
yet? Do we use 25G, 33.3G, 40G, 50G? This future-gazing is a
tricky business.
Best wishes,
Jugnu
From: Trowbridge, Stephen J (Steve)
[mailto:sjtrowbridge@xxxxxxxxxx]
Sent: Monday, August 14, 2006 3:23 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] MAC Data Rate of Operation Objective
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
-
- From: John DAmbrosia
[mailto:jdambrosia@xxxxxxxxxxxxxxxxxxx]
- Sent: Monday, August 14, 2006 3:20 PM
- To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
- Subject: [HSSG] MAC Data Rate of Operation
Objective
- All,
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- In regards to proposed MAC data rates, I have seen two basic
proposals
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- Proposal A) 100 Gb/s
- Proposal B) Scalable Solution
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- Proposal A supports the traditional 10x increase in speed.
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- 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.)
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- 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.
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- 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.
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- Also for both proposals what are people s thoughts on an objective
that would specify an optional Media Independent Interface (MII)?
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- John
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