Cisco has announced it’s going to support, and perhaps even focus on, “intent-based” networking. At one level this could be viewed as a vindication of a widely held view that intent-modeling is the essential (and perhaps under-supplied or even missing) ingredient in the progression of virtualization. At another level, it could be seen as another Cisco marketing strategy. The truth is that it’s a little of both.
At the heart of today’s issue set is whole different notion, that of determinism. The old-day time-division-multiplexed networks were deterministic; they worked in a specific way and provided very specific capacity and SLAs. As packet networks, and particularly the Internet, evolved, networking tossed out strict determinism in favor of lower cost. We had “best efforts” networks, which is what dominates today.
So what does this have to do with “intent?” Well, best efforts is increasingly not good enough in a competitive market, but nobody wants to go back to full determinism to achieve something better—the cost would be excessive. The alternative is to somehow couple service requirements into packet networks in a way that doesn’t break the bank. In an intent model, elements of infrastructure are abstracted into a black box that asserts interfaces and an SLA but hides the details. Intent modeling is therefore a way of looking at how to express how deterministic a network has to be. It also leaves it to the vendor (and presumably the network-builder) to decide how to fulfill the intent.
Intent modeling is an incredibly important tool in realizing the benefits of virtualization and infrastructure transformation, because it lets operators create abstract building-blocks (intent-based black boxes) that combine to build networks, and that then evolve internally from legacy to modern technology. A good evolutionary intent model has to be anchored in the present, and support the future.
Cisco’s approach to transformation has always been what cynics would call “cosmetic”. Instead of focusing on building SDN or building NFV, Cisco has focused on achieving the goals of those technologies using behaviors coerced from current technology. At one level, this is the same kind of marketing gloss Cisco has been famous for, for decades in fact. At another it’s reflective of a simple truth, which is that transformational technologies that do the transforming by displacing legacy infrastructure are exceptionally difficult to promote because of cost and risk.
There really isn’t much new in the Cisco intent approach. Cisco has always been an advocate of “policy-based” networking, meaning a form of determinism where the goals (the “intent”) is translated into a hierarchy of policies that then guide how traffic is handled down below. This is still their approach, and so you have to wonder why they’d do a major announcement that included the financial industry to do little more than put another face on a concept they’ve had around for almost a decade.
One reason is marketing, of course. “News”, as I’ve always said, means “novelty”. If you want coverage in the media rags (or sites, in modern terms) then you have to do something different, novel. Another reason is counter-predation. If a competitor is planning on eating its way along a specific food chain to threaten your dominance, you cut them off by eating a critical piece yourself. Intent modeling is absolutely critical to infrastructure transformation. If you happen to be a vendor winning in legacy infrastructure, and thus want to stall competitors’ reliance on intent modeling as a path to displacing you, then you eat the concept yourself.
OK, yes, I’m making this sound cynical, and it is. That’s not necessarily bad, though, and I’d be the first to admit that. In one of my favorite media jokes, Spielberg when asked what had been the best advice he’d received as a director, said “When you talk to the press, lie.” But to me the true boundary between mindless prevarication and effective marketing is the buyers’ value proposition. Is Cisco simply doing intent models the only way they are likely to get done? That, it turns out, is hard to say “No!” to.
We have struggled with virtualization for five years now, and during that period we have done next to nothing to actually seize the high-level benefits. In effect, we have as an industry focused on what’s inside the black-box intent model even though the whole purpose of intent models is to make that invisible. Intent modeling as a driving concept for virtualization emerged in a true sense only within the last year. Cisco, while they didn’t use the term initially, jumped onto that high-level transformation mission immediately. Their decision to do that clearly muddies the business case for full transformation via SDN and NFV, but if the proponents of SDN and NFV weren’t making (and aren’t making) the business case in any event, what’s the problem?
Cisco has done something useful here, though of course they’ve done it in an opportunistic way. They have demonstrated the real structure of intent models—you have an SLA (your intent) on top, and you have an implementation that converts intent into network behavior below. Cisco does it with policies, but you could do the same thing with APIs that passed SLAs, and then have the SLAs converted internally into policies. Cisco’s model works well for homogeneous infrastructure that has uniform dependence on policy control; the other approach of APIs and SLAs is more universal. So Cisco could be presenting us with a way to package transformation through revolution (SLAs and APIs) and transformation through coercion (policies) as a single thing—an intent model.
They could also be stimulating the SDN and NFV world to start thinking about the top of the benefit pyramid. If Cisco can make the business case for “transformation” without transforming infrastructure, bring service control and a degree of determinism to networking without changing equipment, then more radical approaches are going nowhere unless they can make a better business case.
Is Cisco sowing the seeds of its own competition? More likely, as I suggested above, Cisco is seeing the way that a vulnerability might be developing and working to cut it off. But one way or the other, Cisco is announcing that the core concept of SDN and NFV isn’t just for SDN and NFV to realize. Those who don’t want five years of work to be a science project had better start thinking about those high-level benefits that Cisco is now chowing down on. There are only so many prey animals in the herd, and Cisco is a very hungry predator.