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Cisco SDN response: Programmable networks, not OpenFlow

With Cisco ONE, Cisco moves beyond software-defined networking, introducing APIs and virtual network overlays that enable programmable networks.

Cisco says software-defined networking (SDN) and OpenFlow are only a fraction of a broader solution: programmable networks.

So the Cisco SDN strategy, launched at Cisco Live this week and dubbed Cisco Open Network Environment (Cisco ONE), promises to open up the entire network stack for programmability, but focuses more on network overlays and opening APIs than on centralizing network control and management with a controller.

While most SDN strategies separate the control and forwarding planes in order to make networks more programmable, Cisco claims that customers want to extend that programmability up and down the network stack, from the transport layer all the way up to the network services layers (Layers 4-7) and the orchestration and management plane.

"Most of Silicon Valley has been talking about Layer 2 and 3, and we've been missing the discussion about Layer 4-7," said Andre Kindness, senior analyst with Forrester Research.

Cisco SDN response: OpenFlow for researchers, APIs and overlays for everyone else

Cisco will address demand for programmable networks in three ways. First, it will offer software-defined networking and OpenFlow for some users. But in most cases, Cisco will help its customers by supporting virtual network overlays, like LISP and VXLAN, to bridge the physical and virtual worlds. Furthermore, it will introduce a software development kit (SDK) that makes all of its routers and switches programmable through a universal API.

On the OpenFlow front, in the third quarter of 2012 Cisco will release an OpenFlow controller and an agent to be deployed on its Catalyst 3750-X and 3560-X switches for proof-of-concept deployments. This technology is aimed solely at universities and research institutes that are working on software-defined networking research, said Prashant Gandhi, senior director of product development at Cisco.

Beyond that, Cisco is introducing onePK, a new API and software development kit (SDK), which runs on all of Cisco's major operating systems: IOS, IOS-XR and NX-OS. With it, customers or third-party developers can write applications and have them interact with all layers of the network stack across all of Cisco's switching and routing platforms. The API will be available through a simple software update in the last quarter of this year.

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"We can expose the capabilities that we have in our ASICs to applications so that it's really cohesive across software and hardware," Gandhi said. "The programmability needs to happen on multiple planes. In the service provider, we have optical transport that needs to be provisioned to meet an SLA. And there are network services -- whether they be visibility, monitoring or security -- that need to be deployed on a given workload."

Furthermore, the Nexus 1000v distributed virtual switch will serve as a key component for Cisco's approach to virtual network overlays. Cisco has added a REST API and a Quantum plug-in that enables customers to build virtual cloud networks with OpenStack and other orchestration technologies. The 1000v will also feature a VXLAN gateway to bridge between the physical and virtual environments in a network overlay system.

Although onePK is by nature a proprietary API that runs on Cisco's operating systems, the company appears to want programmable networks to remain a standards-driven movement, with commitments to OpenFlow, OpenStack and other technologies.

"Today the programmability of the network is defined as the interaction between the control and forwarding plane. That's OpenFlow. But beyond the control and forwarding plane to other layers, whether network applications or orchestration tools, that interface is typically vendor-specific. Cisco would like to see that interface also be standards-based," Gandhi said

Cisco SDN: Programmable networks with northbound intelligence

Cisco ONE focuses on extracting the intelligence that exists within the company's routing and switching platforms and feeding that information into the management and network services layers of the network. This northbound feedback enables programmable networks that are more intelligent about the decisions they make.

"Everyone has been talking about southbound communications from the [SDN] controller to the network," Kindness said. "No one has been talking about feeding back into orchestration systems so that you can make intelligent decisions [about the network]."

For instance, an enterprise doesn't want to migrate a virtual machine across a data center without knowing if the network is ready for the move, he said.

"How do you know if you have enough bandwidth for it?" Kindness said. "With SDN you might be able to carve up the network, but that information needs to feed up into a system."

Cisco ONE: Hedge or revolution?

Network engineer and blogger Ethan Banks (CCIE #20655) described Cisco ONE and onePK as a "wait-and-see" approach for Cisco.

"They aren't giving customers SDN as such," he said. "There's no management tool included using onePK. Cisco is waiting to see what customers will do with it. It's up to the customers to do actual SDN, leveraging onePK. I think if Cisco sees customers going crazy, building interesting solutions around onePK, they might start creating a new way of managing, provisioning and operating networks. OnePK is the cautious approach. And it's in a very early stage."

However, Cisco sees Cisco ONE and onePK as a vanguard for a major shift in the networking and IT industry.

"It is going to be a cultural transition, and those don't happen overnight," Kiran said. "We have to handhold our customers through this transition. So over time Cisco will bring in developer portals, training and certification programs and a rich set of ISVs [independent software vendors]. We'll be looking at several proofs of concept with onePK where it will fire up the imagination of what is possible with programmable networks."

In fact, accepting the notion of programmable networks internally was something of a religious transformation for Cisco, according to David Ward, vice president, service provider chief architect and CTO at Cisco.

The networking industry has two major "religious" points of view that initially appeared to run counter to the SDN and programmable networks movement. "Religious point number one was with respect to building a router or switch. If the state of it is in the config file, it will reboot to that state. That religious tenet needed to be broken. That's been around since the 1960s," said Ward. "SDN brings the ability to program state into the control plane that is not held in the config file at all. This is a major shift. The second major religious tenet is around the notion of a centralized view of topology. Routers and switches make decisions based on the environments around them."

SDN and programmable networks initially appear to take that decision making away from the routers and switches, which again runs counter to decades of networking dogma, Ward said. However, SDN and programmable networks don't necessarily negate tried-and-true technologies like dynamic routing protocols. Instead, they enhance them and allow network engineers to have more control over how they use them.

Let us know what you think about the story; email: Shamus McGillicuddy, News Director



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