By getting it software qualified to run on Cumulus switches, Midokura has given itself a way to connect physical networks into its MidoNet network virtualization scheme.

The companies are announcing the partnership this week. It's less about integration and more about getting MidoNet to talk to switches that run Cumulus Linux.

Specifically, they can talk via the Open vSwitch Data Base (OVSDB) protocol, which provides access to a switch's configuration database. OVSDB is the protocol used by VMware to get a switch to become an endpoint for a VXLAN tunnel — a temporary Layer 2 connection used for tasks such as connecting one virtual machine to another.

So, what we're talking about here is creating a VXLAN tunnel that connects a Cumulus-driven switch to elements inside the MidoNet virtual network.

Midokura already offers software gateways that can do this. What's different now is that the Broadcom Trident II switching chip is available, and with it, native hardware support available for creating VXLAN tunnels. This frees up general-purpose processors from having to use up cycles trying to run VXLAN (and possibly not running it at wire speed).

Cumulus is a software company, offering a Linux operating system to run on bare metal switches, also known as white boxes. It doesn't make its own switches (although it can sell Cumulus Linux pre-loaded on white boxes.) Its OS has been adapted to tap some of the Trident II features, VXLAN tunneling among them.

The companies say they will be able to demo the results of their partnership in May, with general availability expected in the third quarter of 2014.

Many vendors ship or plan to ship Trident II-based switches. Moreover, OVSDB and VXLAN are at the heart of VMware's NSX network-virtualization platform. When NSX came out in August, plenty of switch vendors pledged they could interoperate with it, in most cases because Trident II, OVSDB, and VXLAN figured into their plans as well.

In other words, Cumulus isn't the only switch company Midokura could have partnered with. But Midokura officials say Cumulus better fits the philosophy of openness prized by so many other SDN-related companies.

“Yes, engineering [at Midokura] is looking at those alternative platforms,” says Dan Conde, Midokura's director of products. “But we like the way Cumulus looks at it. Cumulus is more aligned with people who like to work at scale and work with automation.”

Controlling the physical and virtual networks together is becoming a theme in the industry, and rightly so, since it's a pragmatic approach to SDN. Big Switch Networks, for example, is basing its strategy around using one controller for the physical and virtual networks.