Cisco announced today that it's signed a deal to acquire Embrane, the Layer 4-7 player that was one of the earlier software-defined networking (SDN) startups to emerge.

Yes, today happens to be April 1. But an Embrane acquisition is way too believable to be a joke... I think.

That's because Cisco participated in Embrane's $14 million funding round last year, which many took to be a sign of a pending acquisition. And Embrane has already begun intertwining with Cisco's Application Centric Infrastructure (ACI).

The deal is expected to close this quarter, according to the Cisco blog post announcing the deal; that might be referring to Cisco's fiscal quarter, which ends in April. Terms were not disclosed.

Embrane would be added to the Insieme Business Unit, which is the home of ACI, and thus becomes part of Cisco's SDN story. (Although it's always good to remember that "ACI" can refer to just the Nexus 9000 switch without any SDN involved.)

We saw that play out in October, when Brazilian cloud provider UOL struck a deal to use Embrane's software and Cisco's ACI.

The acquisition brings Cisco back into the Layer 4-7 world, in a sense. The company discontinued its Application Control Engine (ACE), a load balancer for its switches, in 2012 and has since turned to Citrix and F5 as partners.

Embrane didn't intend to develop Layer 4-7 functions itself, though, so it's feasible that the startup could co-exist with those vendors in the Cisco universe.

In 2013, Embrane was pitching the concept of containers for moving Layer 4-7 functions and building them into service chains. (This was before Docker turned Linux containers into a big thing.) More recently, Embrane described itself as managing the life cycle of virtual Layer 4-7 functions.

When a network service is created, Embrane's Elastic Services Manager calls the necessary firewalls and/or load balancers into existence on the proper servers and, in the case of ACI, can notify the Application Policy Infrastructure Controller (APIC) of the functions' existence. Embrane also tears down the virtual functions when they're no longer needed.

Embrane has already been doing this for functions from Citrix, A10, and Sourcefire (which was acquired by Cisco after striking a partnership with Embrane).