One of the stars of last week's Ericsson-Ciena partnership announcement was IP over DWDM, a technology convergence the industry hasn't heard much about recently. Ciena traditionally hasn't championed it, but Ericsson is clearly excited about it.

"This is about unification and convergence of optical and IP," Jan Haglund, head of IP and broadband at Ericsson, said on a conference call with reporters and analysts last week. He called IP a roughly $15 billion market today and WDM a separate $10 billion market. "There is market going forward where optical and IP are growing together. We estimate that, by 2020, north of 30% of the market will be influenced by IP over WDM convergence. If you want to be a strong IP player or a strong optical player or both, you need to be addressing that part of the market."

That's why a key focus of the joint development between Ericsson AB (Nasdaq: ERIC) and Ciena Corp. (NYSE: CIEN) will be to create IPoDWDM interfaces (Ericsson called it IPoWDM, but we'll stick with the more common acronym) between Ciena's optical modules and Ericsson's SSR 5000 routers. (See Ciena, Ericsson Embark on SDN, Optical Love Affair and Ericsson's Ciena Tieup: It's a Migration Thing.)

Haglund's comments represent fairly heady enthusiasm for a technology approach long championed by Cisco Systems Inc. (Nasdaq: CSCO) that has had a relatively quiet couple of years. The most notable IPoDWDM adopter in the last two years was Deutsche Telekom AG (NYSE: DT), though Telefónica SA (NYSE: TEF) and others have conducted trials. (See DT's All-Cisco, No-Optical Network, Telefónica & Cisco Run 100G IPoDWDM, and Doubts Still Dog IPoDWDM.)

The IPoDWDM interface also is a surprising development for Ciena. The optical vendor has spent years marketing alternatives to fully converged IPoDWDM.

"Ciena's historical positioning has been not to do IP over WDM," Sterling Perrin, a Heavy Reading senior analyst, told us. "They came up with alternatives to it because they only had the optical systems. They would do a router bypass with OTN switches, for example, where optical traffic would not touch the router."

It seems like Ciena is changing its architectural thinking. However, Ciena senior vice president Tom Mock told Light Reading that isn't the case; Ciena believes that doing IPoDWDM with Ericsson will allow Ciena to target more IP-centric deployment opportunities.

"Even though there is a router component to this, it doesn't indicate a change in our view or a change in what we think the best architectures are," Mock said. "What we and Ericsson both realize is that there are a whole range of network architectures out there, and what any individual operator chooses is going to have much more to do with the individual services it's trying to offer."

Somewhere, Cisco Systems CEO John Chambers is smiling about IPoDWDM finally getting its due attention. Nevertheless, he might also want to consider the potency of an Ericsson-Ciena pairing on IPoDWDM before he gets too happy. The Ericsson-Ciena approach offers a multi-vendor take on IPoDWDM in competition to the all-Cisco approach, and like so much else these days, that option comes courtesy of the SDN movement.

"Cisco has been offering this since 2005 on the CRS, and now it's on all its high end platforms," Glen Hunt, principal analyst for transport and routing infrastructure at Current Analysis, told us. "But what has been missing is the ability to manage it in a multi-vendor environment. SDN offers some relief here."

Perrin said SDN can now be the control and management mechanism for IP routers and WDM equipment to work together more seamlessly. "If that is the case, they can still be physically separate boxes," and nothing is keeping other vendors from pursuing the same kind of IPoDWDM path.

"I don't think a lot of operators are interested in a single-vendor integration of IP and WDM," he said. "They want to be able to mix vendors, so if Cisco or Ericsson or whoever wants to be a single vendor for IPoDWDM, I don't think that would gain much traction."

— Dan O'Shea, Managing Editor, Light Reading