Even optical system vendors that believe in the longevity of 40 Gbit/s need to have a solid 100Gbit/s plan in place right now, according to the findings of the latest Heavy Reading report on next-generation transport developments.

That's because most of the carriers surveyed by Heavy Reading expect to make purchasing decisions about 100 Gbit/s before 2012 is over, while 45 percent of them predict they'll have their choice down by the end of this year. So, having a 100Gbit/s strategy in place now, even if the products aren't shipping yet, is crucial, analyst Sterling Perrin writes in "100Gbit/s Transport: Forecast & Analysis."

"Even staunch 40G proponents realize that 100G is the technology endgame and that even 40G opportunities will be severely limited without a solid 100G roadmap in place," Perrin writes.

As for when revenues might appear from all this, most predictions say 2012 will be the year when 100Gbit/s deployments really catch fire (not literally, of course). Recently, Ciena Corp. (NYSE: CIEN) CEO Gary Smith told investors that it might be even sooner than that. (See 100G Watch: Chips Get Merger Fever.)

The time spent on developing 40Gbit/s hasn't necessarily gone to waste, though. Shipments of 40Gbit/s DWDM interfaces will outpace those of 100Gbit/s at least through 2015, Heavy Reading believes, although that's partly because a carrier inherently needs fewer 100Gbit/s than 40Gbit/s interfaces to address any given bandwidth amount.

The 40Gbit/s generation "will continue to capitalize on a market window for high speed transport that will remain open until the 100G supply chain fully matures," Perrin writes.

The report discusses the technology behind 100Gbit/s interfaces and summarizes Heavy Reading's market forecasts for DWDM shipments. It also profiles the 100Gbit/s plans of Alcatel-Lucent (NYSE: ALU), Ciena, Huawei Technologies Co. Ltd. , Infinera Corp. (Nasdaq: INFN), NEC Corp. (Tokyo: 6701), Nokia Networks and others.

— Craig Matsumoto, West Coast Editor, Light Reading