I said in a number of blogs last week that 5G wasn’t an automatic savior for SDN and NFV. It’s not that neither concept could support 5G, or even that 5G wouldn’t be better if SDN and NFV were incorporated. There are instead two critical truths to deal with. First, there isn’t anything currently in 5G that would demand the use of SDN or NFV. Second, the best applications of SDN and NFV within 5G would be just about as compelling if they were deployed outside, and before, 5G. To win, it’s my contention that SDN and NFV can’t rely on 5G for support; they have to anticipate it.
Presuming this is true (which I believe, but which you’ll have to decide for yourself) then what has to be done in SDN and NFV to do that essential anticipating? How could the two technologies evolve and change in focus to make the most of the 5G windfall, and perhaps even earn some respectable bucks before it? That’s what we’re going to deal with today, sometimes with SDN and NFV together and sometimes considering one or the other.
There is one central truth for both technologies. Nothing that doesn’t pull through carrier cloud has any chance of generating a significant opportunity for either SDN or NFV. In fact, carrier cloud is so much the lead technology here that both SDN and NFV in operator missions should be considered only in that context. That particular truth is good for SDN, whose principle success has come in the cloud computing data center, but not so good for NFV.
The first and foremost point for NFV is think multi-tenant and not service chain. Too much time has been spent focusing on NFV virtual CPE (vCPE) missions that are useful primarily to business customers, and that are probably best supported via versatile mini-server-like CPE, not carrier cloud. The difference between NFV and carrier cloud is that NFV has a single-tenant focus and nearly all the applications that are credible drivers of carrier cloud are multi-tenant.
All of mobile infrastructure is multi-tenant, and not just today. Do you think 5G network slicing is going to slice every mobile user their own network? Nonsense. Yes, you could use NFV principles to deploy elements of IMS or EPC, but aren’t these two applications really carrier cloud and not NFV? What role could NFV constructive play in multi-tenant feature deployments that OpenStack by itself couldn’t do just as well?
On the SDN side, Issue One is get out of the data center! Network slicing in 5G is just a cry for efficient partitioning of networks using some form of virtualization, which could be either something done below Ethernet/IP (virtual wire) or something above (tunnels, overlay network). Do you think 5G planners sat around in a bar and dreamed up stuff to ask for absent any actual interest among the operators they represent? More nonsense. There is a current mission for network slicing—several in fact.
If you look at the market from a distance, it’s clear that there’s been continued groping toward a model of networking to replace OSI’s seven layers. Over a decade ago, Huawei presented their “Next-Generation Service Overlay Network.” Nicira made news with an overlay-based “SDN” technology for cloud data centers. SD-WAN is being presented as a successor to MPLS, and Nuage’s overlay SDN is in my view the best current model of virtual networking available. All overlay concepts, all based on the presumption that it’s better to create service, user, or application networks using an overlay than to require that the user participate in what’s essentially transport-network behavior.
The Third Network model of the MEF is the right model in perhaps too limited a forum. An overlay has to be underlay-independent. Should we even try to define a specific approach, or should we agree that any overlay is fine among consenting adults? The SDN world needs to step back and address goals and benefits. The operators need to push for that, and those network vendors who aren’t too wrapped around current-network revenue streams need to push it too.
Coming back around to NFV, the next point is the need to find opportunity in dynamism. NFV as it has evolved harnesses cloud computing tools in a service-feature context. That’s wrong in two dimensions. First, limiting NFV to a service feature context—limiting it to virtual functions inherited from physical network devices—pulls it out of the truly valuable mission of supporting capabilities that not only were never part of a device, they couldn’t be so. Second, if you’re going to harness a technology capability to frame your own features, your first market obligation is to differentiate yourself from your parent, which NFV hasn’t done.
A function that’s put someplace and lives there till it breaks is more like a cloud function than a virtual network function. Scaling, resiliency, and other attributes of features can help to create essential dynamism in a mission, but has NFV really done anything for scaling and resiliency other than to specify that it has to be there? What cloud application isn’t supposed to have the attributes? In the cloud, we know these attributes are most likely created via DevOps. We know how DevOps works. What creates them in NFV?
5G is supposed to be able to provide low-latency paths by providing for local hosting of features. OK, what features? Most of the stuff we propose to host comes from things like IoT, whose “features” are a lot more like application elements than like network functions. But IoT does potentially expose both per-user “agent processes” and multi-tenant shared services. It would be a great place to start in building a useful model of NFV.
That same area of IoT and local processes unites SDN and NFV in another point—it’s time to separate functions. Data-plane activities should be primarily SDN elements. If we’re going to stick a firewall process into the data plane, then we should be seeing it as an adjunct to a broader SDN mission to enhance security. If we’re going to talk latency, we have to decide if we’re talking about data-plane latency—which only data-path elements can assure—or transaction/control latency, which local hosting of functions can actually help with.
As I suggested earlier in this blog, there’s not much credibility to spawning single-tenant VNFs for the broad consumer market. That market almost demands multi-tenant elements, and the fact this was missed in planning for NFV means that we really needed to ask ourselves whether NFV missions were associated with market niches whose cost tolerance would never permit separate function deployment and management.
All of the things that SDN and NFV need to do could be done today, without a whiff of 5G justification. They could have been done from the first, and had they been I think we’d have seen far more adoption of SDN and NFV today. We need to learn a lesson here, which is that good ideas are ideas that deliver on benefits. You don’t have to pull them through with a vessel. I know that I’ve been hopeful that 5G investment would provide an opportunity for SDN and NFV, and I believe it will—but only an opportunity. Just as the two technologies have failed to target their own key business case in the past, they could fail in the 5G future. If that happens, then 5G will advance without them.
But not as far. The concepts that differentiate 5G from 4G are the same concepts that should have differentiated SDN and NFV from legacy networking. Can 5G redevelop these notions, notions that were ignored or underplayed in the past, without SDN and NFV? It’s a dilemma because either 5G would have to explicitly reference SDN and NFV and then become dependent on their fulfilling a benefit mission set that’s not been fulfilled so far, or ignoring them and defining technologies anew. Neither is going to be easy, but one or the other has to be done.
This isn’t a technology problem, either. SDN and NFV technology and “carrier cloud” could be done right almost instantly. It’s a positioning problem. Vendors have taken the view that operators are “demanding” all this new stuff, when the truth is that operators (at the CFO level in particular) aren’t even sure the new stuff is useful. A vendor who supports NFV supports nothing in particular; same with SDN and carrier cloud. A vendor who can take the time to develop the business case for transformation to SDN, NFV, carrier cloud, and 5G is a contender. However, vendors have always been reluctant to do market education because it benefits their competitors. So, do the media or analyst communities do the educating? Nonsense again, and that’s the core of our real challenge in transformation. I hope it gets solved with the 5G process, but I’m still skeptical.