Originally published in the book:Gray, Ken & Nadeau, Thomas. Network Function Virtualization, 1st Edition. (2016). Morgan Kaufman, also available here.

This book by Ken and Tom on NFV is perhaps the first time they've laid out both a fantastic review of the vast landscape of technologies related to virtualized networking and woven in a subtle argument and allusion to what the future of this technology holds. I may be drunk on my own Koolaid, but I certainly read the book with a specific lens which is one in which I asked the question "Where are we on the maturity continuum of the technology and how close is it to what operators and customers need or want to deploy?" The answer I believe I read from Tom and Ken is that "We've only just begun." (Now try and get Karen Carpenter out of your head while reading the rest of this :)) What I mean by this is that over the last say 6 years of trade-rag-eye-ball-seeking articles, the industry has lived through huge hype cycles and 'presumptive close' arguments of download-install-transition-your-telco/mso to a whole new business.

What K/T lay out is not only an industry in transition but one that is completely dependent on the pace being set by the integration of huge open source projects and proprietary products, proprietary implementations of newly virtualized appliances, huge holes in the stack of SW required to make the business: resilient, anti-fragile, predictable, supportable, able to migrate across DCs, flexibly re-arrangeable, a whole mess of additional x-ilities and most importantly... operate-able and billable. Thing is, this transition MUST happen for the industry and it MUST happen in many networking dependent industries. Why? Because the dominant architecture of many SPs is one in which flexible data centers were not considered part of the service delivery network. On-demand user choice was not the norm. Therefore, trucking in a bunch of compute-storage-switching (aka Data Centers) does not by itself deliver a service. SPs build services in which there are SLAs (many by regulation in addition to service guarantees), guarantees of experience, giving access to any and all new devices that arrive on the market and as a goal focus on building more and more uses of their network. The key thing that this book lays out is that: it's complex, there are a ton of moving parts, there are layers upon layers, there are very few people if in fact any that can hold the entire architecture in their head and keep track of it. And most importantly: we are closer to the starting line than the finish line.

Thankfully as K/T laid out in another book, we have made it through the SDN-hype cycle and it's being rolled out across the industry. We watched the movie "Rise of the Controllers" and the industry is settled down and deploying the technology widely. Now we are to the point where virtualizing everything is the dominant topic. Technology progresses. Thing is, it requires a lot of "stack", and all that's necessary in that stack doesn't exist today and is in various stages of completeness, but not integrated into something consistent or coherent yet. Also, when someone says VNF (virtualized network function) or NFV (network function virtualization): A) it applies to more than networking related stuff, see video production and playout services and B) the terms were defined when hypervisors where the only choice for virtualization. Now that containers are available; we have to clearly set the industry goal that "cloud native" (which is basically a synonym for containerized applications) is the ultimate endpoint; until the next wave comes in. The real point is that lifting and shifting of physical appliances to hypervisor based VNFs (necessary first step but not sufficient) led to one particular stack of technology but cloud-native leads to a different variant. One in which use of DC resources is dramatically lower, time to boot/active service is faster and parallelism is the central premise. For the love of all the G*ds, I truly hope that the industry doesn't stall prematurely. Without knowing what K/T are up to next; it's an easy prediction to make that this book will have a potential for 42 versions of publication as today it documents the first steps toward this industry revolution.

The implicit argument that I read throughout the book is that we are seeing the end of the feudal reign of siloed organizations and technical structure of long lasting beliefs of the architecture of the Internet. The next conclusion I came to is that we are at the point where the OSI model should only be taught in history books. It's close to irrelevant and assumptions that don't hold water today. What K/T laid out (although they don't spell it out this way so I'll take the liberty) is that there are now so many more explicit first-class citizens in the Internet architecture that our old notions of layering have to be wholesale rejected. What are these new first class citizens? Identity, encapsulation/tunneling, specific application treatment, service chains, security, privacy, content as endpoint, dependent applications performing as workflows, access agnosticism, multi-homing, location independence, flat addressing schemes, unique treatment/augmentation per person, and a desire that the network and the service someone or some business requested reacts to repair itself and reacts to experience that is desired... to name a few.

Ok, let me dial it back a little and try and explain how I got this worked up. I reached the same point K/T discuss in the book that the stack to virtualize networks goes way beyond the concepts of SDN. As the reader probably understands, SDN is a key ingredient to enable NFV but alone it only does part of the job. I'm going to switch terms from what K/T use and describe the high-level goal as "Reactive Networking."

The industry has been making progress towards this target in the open source community and somewhat in standards bodies (e.g. MEF, IETF, ETSI etc). Services orchestration now includes SDN controllers. Many are working toward an implementation of MANO, the orchestration framework that can create virtualized services per tenants or customers. There are service orchestration products on the market; I lumped them all together in the greenish bubble on the left. The network can now be built around strong, programmable forwarders. Providing a solid analytics platform is needed immediately and work is already underway. This is key because in this day and age we can't actually correlate a network failure to video quality analytics. Meaning that a country full of video viewers just had their content tile because a link went down somewhere and no one has any idea what caused it. Yep, it's the case right now we can't correlate any networking or NFV event to service quality analytics. It's all siloed. Everything today is compartmentalized to its fiefdom or rigidly stuck in it's OSI layer. One of the magical cloud's most important contributions to the industry is the notion of a PaaS. Request a service and voil