“Cisco ACI versus VMware NSX” is one of the top questions we get on the networking team from Gartner clients. That said, ACI and NSX provide very different approaches to solving networking challenges – ACI is a programmable Ethernet Fabric that integrates hardware and software, while NSX is a network overlay.
Both were included in the 2015 Data Center Networking Magic Quadrant and my colleague, Simon Richard just published research specifically on this topic. Choosing between ACI and NSX is a strategic network decision, and is way beyond just a networking thing. As Simon points out: The choice should include significant input from more than just than the network team. The scope of the operational changes that will result from deploying either Cisco ACI or VMware NSX will justify a longer time horizon than the usual data center network upgrade.
And of course, there is always the option to run them together, which is also a topic of increasing interest from our clients: Because VMware NSX can run over any hardware, it is technically feasible to combine it with Cisco ACI. However, deploying both solutions together will be prohibitively expensive for most enterprises. As long as the NSX and APIC controllers do not communicate, enterprises will run duplicate functionality such as security policies and will run nested VXLAN tunnels, further complicating the architecture.
If you’re trying to decide between them, I would highly recommend checking out the research:
Comparing Cisco ACI and VMware NSX: Programmable Fabrics or SDN Overlays?
Summary: Enterprises are evaluating both Cisco ACI and VMware NSX to increase their data center network agility and fortify their security postures. These solutions offer different approaches for solving a similar set of challenges. This document provides guidelines for comparing the approaches.