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Between Cisco and VMware SDN, which will network engineers choose?

In the Cisco vs. VMware SDN battle, Cisco ACI may win out among network engineers, who are more comfortable with the hardware-centric approach.

In the last few months, Cisco and VMware launched SDN strategies with starkly different angles. Cisco Application Centric Infrastructure (ACI) is a hardware-centric approach to data center network programmability, while VMware NSX goes for network virtualization through all-software network overlay technology. In the battle between Cisco and VMware Inc., user support will be divided between two SDN camps -- networking and systems engineers.

SDN is a young technology and there are many varied strategies, so it makes sense that vendors will leverage what they already know best in their approach. For VMware, that means bringing networking into the virtual world and de-prioritizing the focus on hardware. For heavyweight hardware vendor Cisco, it means maintaining dominance in the networking space with SDN that is tightly integrated into the underlying physical infrastructure while still allowing for network virtualization.

In an IT world that is heavily segmented, where finger pointing at security, network, systems, storage, and development groups is the norm rather than a disappointing anomaly, choosing between these SDN strategies will boil down to the technology comfort level of each team. Ultimately, purchasing decisions may be influenced by the group that has the ear of the CTO.

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Network engineers will be much more comfortable with Cisco and its hardware-centric vision. After all, one of the three pillars of the Cisco ACI strategy is the Nexus 9000 series switch line, which runs a trimmed down version of the familiar Nexus operating system. There's also the Application Virtual Switch, which is based on the already well-received Nexus 1000v. The third pillar is the Application Policy Infrastructure Controller, which may not be the network engineer's first love but doesn't have to be implemented right up front. Engineers can run the new switches in Nexus mode until they're more comfortable with SDN, and then they can transition the switches to ACI mode. Only then do network teams have to implement the new controllers that will manage the Nexus 9000 switches.

Systems engineers, on the other hand, will be much more comfortable with the VMware vision of the future, as it brings the promise of network virtualization and control more directly into their world and the existing VMware product portfolio. It remains to be seen how much network control will truly be shifted to systems engineers in an NSX-centric version of the data center, but it is fairly certain that the likelihood of a power shift is much stronger with VMware than with Cisco.

Between Cisco and VMware, will $$$ be a differentiator?

Price competitiveness between the two strategies at this point is murky at best. Cost efficiency will depend strongly on how much a business has invested in which technologies already, and what its needs are going forward.

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NSX will cause a turf war

Cisco ACI will be the most competitive choice for data centers or large enterprises that see port density as a significant driver. East-West traffic may win in the NSX world, but for pure, unadulterated packet movement at high wire-speeds, the Cisco model is a clear winner. The combination of merchant and proprietary silicon allows for compelling per-port pricing on the 9000 series. The caveat is that this level of port-density is much more than many folks -- even a lot of large enterprises -- are going to need. In that case, the NSX model, which requires no up-front hardware upgrade, may win out. The problem is, VMware has not yet made pricing available; it's still unclear. And Cisco has pointed to the fact that in server virtualization, VMware charges a per-VM fee, which is pricy.

Cisco ACI will win out among network engineers

I can't help but think that since buying decisions are made in silos, and the NSX or ACI choice (if you believe it's either/or) fundamentally relates to the network space, Cisco has a definite edge. With Cisco ACI you get the best of both worlds: higher speeds and feeds in a form and function you're already intimately familiar with and invested in. You also get an incremental approach to SDN with a programmatically accessible controller framework using familiar models, such as XML, JSON and Python.

So in choosing either Cisco or VMware for SDN, NSX still feels like a threat to many network folks. And considering the clear marketing message from VMware that implicitly points the finger at the network as being a problem, I just can't see those who are likely making the buying decisions in the network space having warm fuzzy feelings toward NSX. While any one vision of SDN is far from a slam-dunk at this point, it feels to me like this model is in a stronger position than the NSX/network overlay vision.

About the author:
Teren Bryson is a lifelong professional network engineer, VMware programmer and Unix geek. He is also whiskey taster; long-time practitioner of the art of beating computer and telecommunications systems into submission; brain hacker; student of everything; cancer survivor; lover of stuff that does stuff and a freelance writer. Read his blog at and follow him on Twitter @SomeClown.

This was last published in December 2013

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