"The very first thing that they're asking about is, 'Tell me how I can customize your product for my applications,'" May says. "I have very limited ability to customize when I make changes to my network or upgrade my firewall -- that forces me to touch all 300, 400, 500 or 1,000 of my switches. Some of the operational ease that an SDN architecture provides is beginning to become one of the more significant drivers of interest in the enterprise."
Much of that operational ease comes from automation, another key benefit of SDNs. Enterprise IT staffs are resource constrained, in time, manpower and money. The programmability aspects of OpenFlow and SDNs help automate procedures that fit into those constraints, says Don Clark, director of business development for the IT Platform Group at NEC America.
NEC's ProgrammableFlow line of switches are based on OpenFlow.
"The networking and IT staff is having to do more with less resources," Clark says. "And especially as cloud services spin out the networking staff in a traditional networking model is overloaded with service requests. So enterprises are really looking to automate some of the things that today are manually configured.
"Automation brings benefit of not having to develop all of these applications internally," Clark says. "Balancing workloads across data centers, today that's a lot of configuration down on each individual switch. Providing an automated solution that allows them to do that much more dynamically is the kind of thing that allows (enterprise IT) staff to move away from manual configuration and more towards policy."
Weren't VLANs, which were all the rage in networking a decade ago, supposed to virtualize and automate and segment and isolate applications and traffic over a shared infrastructure? They did, but that technology is old now and it limitations are now showing.
"VLANs are difficult to configure and are limited in scope," says HP's Gillai. "We're taking it to the next level with a full virtualized network, with an overlay or segment for a particular application or use case which is isolated from anything else that is going on. Each application or use 'feels' like it has its own network. And it simplifies network management and resource allocation. We're now managing resource pools" instead of individual routers and switches.
"VLANs are very low level," says Nicira's Casado. "Even if you had VLANs as a low level mechansims, would still need someone to update it, configure it, and wouldn't scale because you'd have to trunk everything everywhere; you couldn't go over an L3 boundary."