The party line from Cisco and VMware is that they're not enemies, not even after this week's announcement of the NSX platform, which extends VMware's presence in networking.

There's a lot of doubt about that statement, but it's clear the companies will have to work together to some extent. Specifically, it's a no-brainer that the VCE joint venture will be fitting NSX into its Vblocks platforms of converged compute/storage/networking.

That's not the main plan, of course. Cisco has its own software-defined networking (SDN) architecture, the Application Centric Infrastructure (ACI), and that's going to be what primarily gets promoted for use in VCE's Vblocks.

"We're going to build around Cisco networking and compute," Trey Layton, VCE's CTO, tells SDxCentral. "We're going to deploy, engineer, configure, and enable Cisco's Application Centric Infrastructure [ACI]. That will be a fundamental building block of Vblock systems."

Cisco is politely characterizing this as a difference of opinion with VMware, one that was strong enough to keep Cisco off of the list of NSX partners announced Monday. (Unless you count SourceFire, which is about to become part of Cisco -- a hat tip to Evgeny Zobnitsev for noticing that). Competing switch vendors Arista, Brocade, Dell, HP, and Juniper were all on the list.

Cisco got barraged with questions about this, so on Wednesday, Chief Technology and Strategy Officer Padmasree Warrior explained the position in a blog posting. VMware's software-based approach "places significant constraints on customers" in terms of scale and visibility, and "forces the user to tie multiple third-party components together," she wrote.

VCE has big plans for ACI. "Customers will be able to adapt it into their Vblock systems; there will be new systems that are built to accommodate that capability out of the box; and we're also going to introduce architectural technologies that will interconnect existing Vblock systems and have them unite as one logical Vblock system," Layton says.

But what about all that happy NSX "integration" that VMware is so proud of? Other vendors this week announced future gear that will terminate VXLAN tunnels and will give NSX the visibility to connect physical ports to virtual ports.

VCE will get those networking capabilities too, but in the context of Cisco's ACI, Layton says.

"Our fabric will be Cisco-based. If customers want to deploy virtualized network capabilities, they can do so. They're just going to interface and interact with the Cisco fabric," Layton says. "If a customer were to leverage NSX, they would use policy and programmatic interfaces in the Application-Centric Infrastructure to interact with that infrastructure — very similar to the other announcements that you're seeing."

ACI and NSX will end up communicating via APIs. That opens up a possibility that VCE isn't discussing but that seems obvious: The two sides could end up federating controllers, in the way that HP is doing with NSX, allowing both sides' controllers to be orchestrated by one management system.

Regardless of how well ACI and NSX might play together, the platforms still demonstrate how Cisco and VMware's worlds are colliding.

It's a predictable effect of convergence, as networking, computing, storage, and virtualization all overlap. Rob Lloyd, Cisco president of development and sales, has used the analogy of swimmers accidentally encroaching into one another's lanes.

"VMware and Cisco have different perceptions on opportunities to innovate," Layton says. That doesn't mean they can't sometimes "intersect" and cooperated on (or inside) a product, he says.