There are two network virtualization products being pushed by heavyweight vendors. In this corner: VMware NSX. In that corner: Cisco ACI.
The debate is ongoing how to add agility to networking. The overlay model, like NSX, says that the network can be simple as long as the apps are smart. The controller model, like ACI, says that the network should be aware of the apps.
On the overlay side, the strength is in its deployment simplicity: end nodes communicate with each other, but the network itself (the "underlay") doesn't require any adjustment. Its weakness is the flip side: there's no way to tune the underlay, so there's no way around bottlenecks and other potential artifacts of the architecture.
On the controller side, the strength is the potential of the network to adjust to support whatever flow patterns the app requires. There are two weaknesses: first, if the app doesn't integrate with the controller API, then the controller has to interpret the data it's carrying and make a best guess on optimal configuration; second, the "smart" abilities generally require new hardware, which greatly slows down the rate of adoption.
In the short term (1.5-3 years), it's likely that NSX will be deployed much more than ACI. NSX doesn't "technically" require the server team to involve the network team in the roll-out, and the agility that's grown from virtualization into modern devops will lead both to an increased tolerance for risk and a demand for better network delivery. (As a network guy, I'm used to hearing the network always getting blamed for any problem.) The fertile ground will be large applications hosted either classically or in private cloud, especially where the app is multi-tiered (with lots of local east-west traffic), but may grow as NSX support increases across data centers.
The question is whether ACI will take hold, and where. The fertile ground will likely be single-owner data centers with monetized services, where ACI will be seen as an investment to increase capacity, and API integration can be pushed top-down into the hosted systems. However, the Internet Giants (Google, Facebook, etc.) have demonstrated that they're willing to create their own network technology rather than purchase big-ticket vendor products, and analysts and pundits are declaring that everyone else will move to cloud hosting. Even though that prediction is hyperbole, it does put downward pressure on the ACI target markets.
Keep in mind that 3 years ago, the "future of networks" was OpenFlow, so any future predictions that aren't wildly inaccurate will likely be due to blind luck. :-)
What do you think? That's what the comments are for down below.
