Today's network applications and cloud services has made data centres more utilised and important than ever. This has put big responsibility on the network in data centres to forward traffic reliably, to ensure business continuity. Several techniques to make that process more effective has in recent years emerged, among one of them is Software Defined Networking or SDN as it is usually referred to. The general concept behind SDN is that the network intelligence, such as routing and packet filtering, is moved out of the individual boxes and put into a centralised controller which would be programmed by an administrator which in turn would instruct the now unintelligent boxes how traffic should be forwarded, in contrast to instruct the boxes one by one. There are many SDN protocols available today, both open and commercial. One popular open alternative is OpenFlow capable switches with the OpenDaylight controller. In this paper we investigated and compared two major commercial options: Cisco ACI and VMware NSX. We gave a brief introduction to some common problems in today´s data centres and kept those in mind when doing the comparison of Cisco ACI and VMware NSX. We concluded that ACI and NSX does not try to solve all problems in today's data centres, rather, each focuses on their own set of problems, and sometimes both can be used to complement each other.