Bringing packets into the light

The term "convergence" may be one of the most overused and overhyped words in telecoms, but there's no better way to describe the current interest in flattening the IP and optical layers of the network.

The idea of packet-optical convergence - which in broad terms means taking packet networks (namely Carrier Ethernet), Sonet/SDH and DWDM and flattening them down into one network that does everything those layers do separately - has been around for some time.

However, in early 2009, US operator Verizon threw the gauntlet down to vendors when Stuart Elby, VP of network architecture at Verizon Network & Technology, said at an OFC conference that it intended to transform its global network into a packet-optical transport system (P-OTS) that would combine Layer 1 and Layer 2 functionality and into a much more efficient and cost-effective network with an integrated control plane. And Verizon wanted suppliers to come up with boxes that would help them achieve it.

The basis for Verizon's demand was an internal analysis that found IP transit traffic patterns and demand for flexible routes were so dynamic that IP traffic at the optical layer often didn't have to touch the network routers.

"That adage of 'switch where you can, route where you must' has never gone away, and Verizon wanted its  IP transit traffic that didn't need routing to stay in the optical layer," explains Anup Changaroth, product marketing director for Asia for Nortel Networks' MEN business recently purchased by Ciena. "It's a very costly affair to put routers in place and take your IP traffic up to that layer if you don't need to."

Verizon concluded that to support those dynamic traffic patterns and bypass routers, "it made more sense to have the optical layer using MPLS-TP as the key switching mechanism. And they've been driving vendors to look at that," says Changaroth, adding that carriers in Japan and elsewhere have done their own internal studies and reached the same conclusions in the last six months.

Infonetics, meanwhile, found in a survey last year that two-thirds of service providers plan to combine their data and transport operations sometime next year. And vendors are now jockeying for position to help them do just that.