| Thread Links | Date Links | ||||
|---|---|---|---|---|---|
| Thread Prev | Thread Next | Thread Index | Date Prev | Date Next | Date Index |
|
Jonathon, I agree with your former sentiment about it being against IEEE guidelines, so we must not do it. I am sure Paul agrees. However I don’t agree with the latter sentiment. I think Paul is pointing out a real quandary in our task. I think we can point out cases where the adoption
of components has been substantially impacted by the prices-of-resale, over a lengthy period of time. I am not sure how long we would have to wait for the long term? It seems to be a genuine difficulty in carrying out the analysis we all want to see. I don’t have a solution. Warm regards, Robert From: Jonathan King [mailto:jonathan.king@xxxxxxxxxxx]
Hi Paul,
I cannot support comparing cost at the end user, because (in my opinion) that is quite clearly a price, and would be contrary to IEEE guidelines.
I would like David Law to weigh in on this. In an efficient market economy, the cost of manufacture (not the cost of distribution) of a product, or group of products, is the best indicator for
long term cost to the end user. I think that’s what we (802.3) want to get some indicator of when striving for ‘low cost’ solutions.
Best wishes Jonathan From: Kolesar, Paul
[mailto:PKOLESAR@xxxxxxxxxxxxx]
I also like Jack’s perspective foundation. And I have to agree that a common small port form factor would be valuable. Regarding the PMD cost comparisons, I also agree that picking a common cost basis could eliminate translation problems that come with use of different bases. For
PMD relative costs I am fine with choosing either 10GE SR or LR because I don’t quite appreciate Chris’ concerns over the danger in using LR as the basis. But if there is a problem, it seems like it could be avoided by eliminating the bit/sec factor and instead
using simple cost. However, there is still the issue of picking the point in the supply chain at which the baseline cost is chosen. It could be at the level of the transceiver manufacturer,
or up one level to the switch manufacturer, or off on another branch to distributors, or up one level again to the end user. There can be substantial differences in these costs, which is what likely gives rise to the “order of magnitude” perception disparity
that Chris mentioned. While we are forbidden to talk about it, it is the 500 pound gorilla in the room. In some cases it tips the scales lightly and in other cases it leans its full weight. Yet this weight is what is creating a 100GE market acceptance barrier
in data center deployments. While there is clear cost reduction potential in reducing the multimode lane count based just on the improvement in media cost, the benefit of defining a new single-mode
solution may depend largely on the gorilla, for if we go to a parallel solution the media will only get more costly. So for me the biggest cost question is whether defining a new single-mode solution moves the gorilla from leaning heavily to leaning lightly.
While I’d like to agree to use cost at the transceiver maker level as the basis, it cannot address this big question. If used it will likely result in highly distorted
perceptions and projections because it ignores the order-of-magnitude problem. The only point in the supply chain where transceiver costs and cabling costs come together is at the end user level. This dilemma is hitting me squarely as I try to further my
work on the “Kolesar_Kalculator”. I continue to wonder what good this tool will do if the PMD cost and cable cost are in two different silos without a common basis to bring them together, for it is the combination of the two that defines the total channel
cost that we must optimize. I need to find a way to appease the gorilla. If only Fay Wray were here… From: Chris Cole
[mailto:chris.cole@xxxxxxxxxxx]
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.
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] 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 |