Oracle is buying Corente, maker of SDN (software-defined networking) technology for WANs (wide area networks), in a strike against competitors such as Cisco and IBM. Terms of the deal, which is expected to close early this year, weren't disclosed on Tuesday. With Corente, Oracle will have a suite of network virtualization products that extends from LANs (local area networks) in corporate data centers to WANs, according to a statement.