In concluding my last post, I said I would write a subsequent note on whether Cisco achieved its objectives in its rejoinder to software-defined networking (SDN) at the Cisco Live conference last week in San Diego.
As the largest player in network infrastructure, Cisco’s words carry considerable weight. When Cisco talks, its customers (and the industry ecosystem) listen. As such, we witnessed extensive coverage of the company’s Cisco Open Network Environment (Cisco ONE) proclamations last week.
Really, what Cisco announced with Cisco ONE was relatively modest and wholly unsurprising. What was surprising was the broad spectrum of reactions to what was effectively a positioning statement from the networking market’s leading vendor.
Mission Accomplished . . . For Now
And that positioning statement wasn’t so much about SDN, or about the switch-control protocol OpenFlow, but about something more specific to Cisco, whose installed base of customers, especially in the enterprise, is increasingly curious about SDN. Indeed, Cisco’s response to SDN should be seen, first and foremost, as a response to its customers. One could construe it as a cynical gesture to “freeze the market,” but that would not do full justice to the rationale. Instead, let’s just say that Cisco’s customers wanted to know how their vendor of choice would respond to SDN, and Cisco was more than willing to oblige.
In that regard, it was mission accomplished. Cisco gave its enterprise customers enough reason to put off a serious dalliance with SDN, at least for the foreseeable future (which isn’t that long). But that’s all it did. I didn’t see a vision from Cisco. What I saw was an effective counterpunch — but definitely not a knockout — against a long-term threat to its core market.
Cisco achieved its objective partly by offering its own take on network programmability, replete with a heavy emphasis on APIs and northbound interfaces; but it also did it partly by bashing OpenFlow, the open protocol that effects physical separation of the network-element control and forwarding planes.
Conflating OpenFlow and SDN
In its criticism of OpenFlow, Cisco sought to conflate the protocol with the larger SDN architecture. As I and many others have noted repeatedly, OpenFlow is not SDN; the two are not inseparable. It is possible to deliver an SDN architecture without OpenFlow. Even when OpenFlow is included, it’s a small part of the overall picture. SDN is more than a mechanism by which a physically separate control plane directs packet forwarding on a switch.
If you listened to Cisco last week, however, you would have gotten the distinct impression that OpenFlow and SDN are indistinguishable, and that all that’s happening in SDN is a southbound conversation from a server-based software controller and OpenFlow-capable switches. That’s not true, but the Open Networking Foundation (ONF), the custodians of SDN and OpenFlow, has left an opening that Cisco is only too happy to exploit.
The fact is, the cloud service-provider principals steering the ONF see SDN playing a much bigger role than Cisco would have you believe. OpenFlow is a starting point. It is a means to, well, another means — because SDN is an enabler, too. What SDN enables is network virtualization and network programmability, but not how Cisco would like its customers to get there.
Cisco Knows SDN More Than OpenFlow
To illustrate my point, I refer you to the relatively crude ONF SDN architectural stack showcased in a white paper, Software-Defined Networking: The New Norm for Networks. If you consult the diagram in that document, you will see that OpenFlow is the connective tissue between the controller and the switch — what ONF’s Dan Pitt has described as an “open interface to packet forwarding” — but you will also see that there are abstraction layers that reside well above OpenFlow.
If you want an ever more detailed look at a “modern” SDN architecture, you can consult a presentation given by Cisco’s David Meyer earlier this year. That presentation features physical hardware at the base, with SDN components in the middle. These SDN components include the “forwarding interface abstraction” represented by OpenFlow, a network operation system (NOS) running on a controller (server), a “nypervisor” (network hypervisor), and a global management abstraction that interfaces with the control logic of higher-layer application (control) programs.
So, Cisco clearly knows that SDN comprises more than OpenFlow, but, in its statements last week at Cisco Live, the company preferred to use the protocol as a strawman in its arguments for Cisco-centric network programmability. You can’t blame Cisco, though. It has customers to serve — and to keep in the revenue- and profit-generating fold — and an enterprise-networking franchise to protect.
Mind the Gap
But why did the ONF leave this gap for Cisco to fill? It’s partly because the ONF isn’t overly concerned with the enterprise and partly because the ONF sees OpenFlow as an open, essential precondition for the higher, richer layers of the SDN architectural model.
Without the physical separation of the control plane from the forwarding plane, after all, some of the ONF’s service-provider constituency might not have been able to break free of vendor hegemony in their networks. What’s more, they wouldn’t be able to set the stage for low-priced, ODM-manufactured networking hardware built with merchant silicon.
As you can imagine, that is not the sort of change that Cisco can get behind, much less lead. Therefore, Cisco breaks out the brickbats and goes in hot pursuit of OpenFlow, which it then portrays as deficient for the purposes of far-reaching, north-and-south network programmability.
Exiting (Not Exciting) Plumbing
Make no mistake, though. The ONF has a vision, and it extends well beyond OpenFlow. At a conference in Garmisch, Germany, earlier this year, Dan Pitt, the ONF’s executive director, offered a presentation called “A Revolution in Networking and Standards,” and made the following comments:
“I think networking is going to become an integral part of computing in a way that makes it less important, because it’s less of a problem. It’s not the black sheep any longer. And the same tools you use to create an IT computing infrastructure or virtualization, performance, and policy will flow through to the network component of that as well, without special effort.
I think enterprises are going to be exiting technology – or exiting plumbing. They are not going to care about the plumbing, whether it’s their networks or the cloud networks that increasingly meet their needs, and the cloud services. They’re going to say, here’s the function or the feature I want for my business goal, and you make it happen. And somebody worries about the plumbing, but not as many people who worry about plumbing today. And if you’ve got this virtualized view, you don’t have to look at the plumbing. . . .
The operators are gradually becoming software companies and internet companies. They are bulking up on those skills. They want to be able to add those services and features themselves instead of relying on the vendors, and doing it quickly for their customers. It gives opportunities to operators that they didn’t have before of operating more diverse services and experimenting at low cost with new services.”
Again, this is not a vision that would have John Chambers doing cartwheels across the expansive Cisco campus.
While the ONF is making plans to address the northbound interfaces that are a major element in Cisco’s network programmability, it hasn’t done so yet. Even when it does, the ONF is unlikely to standardize higher-layer APIs, at least in the near term. Instead, those APIs will be associated with the controllers that get deployed in customer networks. In other words, the ONF will let the market decide.
On that tenet, Cisco can agree with the ONF. It, too, would like the market to decide, especially since its market presence — the investments customers have made in its routers and switches, and in its protocols and management tools — towers imperiously over the meager real estate being claimed in the nascent SDN market.
With all that Cisco network infrastructure deployed in customer networks, Cisco believes it’s in a commanding position to set the terms for how the network will deliver software intelligence to programmers of applications and management systems. Theoretically, that’s true, but the challenge for Cisco will be in successfully engaging a programming constituency that isn’t its core audience. Can Cisco do it? It will be a stretch.
Do They Get It?
All the while, the ONF and its service-provider backers will be advancing and promoting the SDN model and the network virtualization and programmability that accompany it. The question for the ONF is not whether its movers and shakers understand programmers — it’s pretty clear that Google, Facebook, Microsoft, and Yahoo are familiar with programmers — but whether the ONF understands and cares enough about the enterprise to make that market a priority in its technology roadmap.
If the ONF leaves the enterprise to the dictates of the Internet Engineering Task Force (IETF) and Institute of Electrical and Electronics Engineers (IEEE), Cisco is likely to maintain its enterprise dominance with an approach that provides some benefits of network programmability without the need for server-based controllers.
Meanwhile, as Tom Nolle, president of CIMI Corporation has pointed out, Cisco ONE also serves as a challenge to Cisco’s conventional networking competitors, which are devising their own answers to SDN.
But that is a different thread, and this one is too long already.