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While few of these surveys (for example the internal one sited by Steve) show significant need for >100m links, most of what has been presented shows that 100m covers majority of links. So we should adopt a baseline standard which supports 100m on OM3, which will lead to the lowest possible cost for majority of interfaces.
We need to decide which approach to take for supporting >100m specifications from the choices outlined by Matt and John DAmbrosia.
The most efficient and easiest to agree on would be an informative annex or annexes. This would give a standardized option (or options depending on application) for supporting longer reaches.
A normative specification which has both 100m and >100m in the specification gets tricky because the >100m portion can become the only standard that matters. So this approach would take more work to make sure that 100m stays as a real baseline standard.
Adding a separate MMF objective for some specific reach >100m is the least efficient and would significantly delay getting a standard out. Hopefully we will find that it is not a necessary path.
But what percent of these shipments are for the extreme lengths?
Some numbers might help clarify what close to 0 means.
For 2008, Lightcounting gives a shipment number of approximately 30,000 for 10GE-LRM (and for 10GE-LX4 it’s about 60,000.) So close to 0 would apply if we were rounding to the nearest 100K. As an aside, 10GE-LRM supports 220m of MMF, not 300m.
300m of OM3 is supported by 10GE-SR, which Lightcounting gives as approximately 400,000 in 2008, so that would be close to 0 if we rounding to the nearest 1M.
Another interesting sideline in looking at these numbers is that 2 years after the 10GE-LRM standard was adopted in 2006, despite the huge investment being made in 10GE-LRM development, and despite very little new investment being made in 10GE-LX4, the 10GE CWDM equivalent (i.e. 10GE-LX4, 4x3G) is chugging along at 2x the volume of the 10GE Serial solution that was adopted to replace it.
This should put some dim on hopes that very low cost 40GE Serial technology can be developed from scratch in two years and ship in volume when the 40GE standard is adopted in 2010.
Well, sadly that’s what has been happening in the 10G world, people are forced to amortize the cost of 300m reach (LRM), while in reality the number of people who need 300m is close to 0.
That’s why I am strongly in support of your approach of keeping the 100m objective as primary goal.
Frank, OM4 can add as much cost as it wants to, the beauty is the added cost goes directly where it’s needed, which is the longer links. Alternatives force higher cost/higher power consumption on all ports regardless of whether it’s needed there or not.
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From: Jeff Maki