Sprint Corp. (NYSE: S) plans to upgrade its optical backbone with 400Gbit/s coherent wavelengths running on Ciena Corp. (NYSE: CIEN) gear, the vendor is announcing Wednesday.

The new backbone will run on Ciena's 6500 Packet-Optical Platform exclusively, Ciena says. The 400Gbit/s part won't come right away, as the interfaces aren't shipping yet. Sprint and Ciena are planning for field trials to run in early 2013.

Sprint was already using Ciena's optical gear in general. The upgraded backbone is part of Sprint's overall Network Vision plan, which includes Alcatel-Lucent (NYSE: ALU), Ericsson AB (Nasdaq: ERIC) and Samsung Corp. in other capacities. (See What I Learned at Sprint….)

Ciena has already said that BT Group plc (NYSE: BT; London: BTA) will be a 400Gbit/s customer as well.

Why this matters
It's further evidence that 400Gbit/s will be important as a stopgap while the industry waits for 1Tbit/s transmission to be developed. Bandwidth demand, it seems, really is that urgent in spots.

AlcaLu implied as much in May, claiming 20 customers are ready to deploy its 400Gbit/s interfaces when they're ready at the end of the year.

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— Craig Matsumoto, Managing Editor, Light Reading