While Alcatel-Lucent (NYSE: ALU), Ericsson AB (Nasdaq: ERIC), Fujitsu Network Communications Inc. , and others are talking up packet optical transport systems as the Next Big Thing in optical networking, Cisco Systems Inc. (Nasdaq: CSCO) espouses a contrarian position on what types of equipment carriers should use to manage their next-generation networks.

"What remains to be seen is: What is the right architecture from a cost-effective point of view, from a new platform point of view, and from a technology point of view?" asks Jeff Maddox, director of product line management for Cisco's Optical Transport business unit.

Maddox -- speaking this week at Light Reading's Optical Expo, on a panel titled "Building Dynamic Optical Networks" -- let it be known that he would be "making some counterpoints to some of the arguments" calling for converged packet optical products.

Everyone can agree that the problem facing networks revolves around scaling Ethernet in the metro core, Maddux said. He also agreed that the next-generation network will be defined by a reconfigurable optical transport layer

But from there, Cisco's theory "is to introduce a more feature-rich transport layer and focus on decoupling that with the IP layer," Maddox said. "Our focus is on this idea of IP over WDM, which is clearly a different approach than the idea of packet optical transport."

It's not just a matter of philosophical differences with how these networks should be built. Maddox seemed to disagree with the underlying concept of an all-in-one packet optical device.

"If you look at the network -- including access, metro, core, regional, and long-haul networks -- to think that any one technology has the right functions and can scale to meet all those needs would be disregarding history behind us."

By contrast, Fujitsu and others have touted converged packet optical systems as the wave of the future. (See Fujitsu Updates the MSPP and Optical Expo-sed.)

Richard Colter, Fujitsu's senior manager of product planning, disagreed with Maddox's assessment of how networks should be designed, saying, "Packet optical networking doesn't mean a closed WDM layer. The question is where the routing layer begins and where the aggregation layer begins."

"The marriage between Ethernet transport and DWDM is going to play an important role in the network," said Massi Tornar, Ericsson's U.S. technical sales manager. But he noted that "there's not a single answer" to how carriers will choose to build their networks.

In the end, both routers and packet optical systems could see takeup in different areas of different carriers, said Hans-Juergen Schmidtke, a VP of solution sales management for Nokia Networks . "I predict a mixture of routers towards the edge and carrier Ethernet in the core," he said.

— Ryan Lawler, Reporter, Light Reading