Enterprise and Service Provider—Once more into the Windmill

There is no enterprise, there is no service provider—there are problems, and there are solutions. I’m certain everyone reading this blog, or listening to my podcasts, or listening to a presentation I’ve given, or following along in some live training or book I’ve created, has heard me say this. I’m also certain almost everyone has heard the objections to my argument—that hyperscaler’s problems are not your problems, the technologies and solutions providers user are fundamentally different than what enterprises require.

Let me try to recap some of the arguments I’ve heard used against my assertion.

The theory that enterprise and service provider networks require completely different technologies and implementations is often grounded in scale. Service provider networks are so large that they simply must use different solutions—solutions that you cannot apply to any network running at a smaller scale.

The problem with this line of thinking is it throws the baby out with the bathwater. Google is using automation to run their network? Well, then… you shouldn’t use automation because Google’s problems are not your problems. Microsoft is deploying 100g Ethernet over fiber? Then clearly enterprise networks should be using Token Ring or ARCnet because… Microsoft’s problems are not your problems.

The usual answer is—“I’m not saying we shouldn’t take good ideas when we see them, but we shouldn’t design networks the way someone else does just because.” I don’t see how this clarifies the solution, though—when is it a good idea or a bad one? What is our criterion to decide what to adopt and what not to adopt? Simply saying “X’s problems aren’t your problems” doesn’t really give me any actionable information—or at least I’m not getting it if it’s buried in there someplace.

Instead—maybe—just maybe—we are looking at this all wrong. Maybe there is some other way classify networks that will help us see the problem set better.

I don’t think networks are undifferentiated—I think the enterprise/service provider/hyerpscaler divide is not helpful to understand how different networks are … different, and how to correctly identify an environment and build to it. Reading a classic paper in software design this week—Programs, Life Cycles, and Laws of Software Evolution—brought all this to mind. In writing this paper, Meir Lehman was facing many of the same classification problems, just in software development rather than in building networks.

Rather than saying “enterprise software is different than service provider software”—an assertion absolutely no-one makes—or even “commercial software is different than private software, and developers working in these two areas cannot use the same tools and techniques,” Lehman posits there are three kinds of software systems. He calls these S-Programs, in which the problem and solution can be fully specified; P-Programs, in which the problem can be fully specified, but the program can only be partially specified because of complexity and scale; and E-Programs, where the program itself become part of the world it models. Lehman thinks most software will move towards S-Program status as time moves on—something that hasn’t happened (the reasons are out of scope for this already-too-long-blog-post).

But the classification is useful. For S-Programs, the inputs and outputs can be fully specified, full-on testing can take place before the software is deployed, and lifecycle management is largely about making the software more fully conform to its original conditions. Maybe there are S-Networks, too? Single-purpose networks which are aimed at fulfilling on well-defined thing, and only that thing. Lehman talks about learning how to breaking larger problems into smaller one so the S-Problems can be dealt with separately—is this anything different than separating out the basic problem of providing IP connectivity in a DC fabric underlay, or even providing basic IP connectivity in a transit or campus network, treating it as a separate module with fairly well design goals and measurements?

Lehman talks about P-Programs, where the problem is largely definable, but the solutions end up being more heuristic. Isn’t this similar to a traffic engineering overlay, where we largely know what the goals are, but we don’t necessarily know what specific solution is going to needed at any moment, and the complete set of solutions is just too large to initially calculate? What about E-Programs, where the software becomes a part of the world it models? Isn’t this like the intent-based stuff we’ve been talking about networking for going one 30 years now?

Looking at it another way, isn’t it possible that some networks are largely just S-Networks? And others are largely E-Networks? And that these classifications have nothing to do with whether the network is being built by what we call an “enterprise” or a “service provider?” Isn’t is possible that S-Networks should probably all use the same basic sort of structure and largely be classified as a “commodity,” while E-Networks will all be snowflakes, and largely classified as having high business importance?

Just like I don’t think the OSI model is particularly helpful in teaching and understanding networks any longer, I don’t find the enterprise/service/hyperscaler model very useful in building and operating networks. The service enterprise/service provider divide tends to artificially limit idea transfer when it wants to be transferred, and artificially “hype up” some networks while degrading others—largely based on perceptions of scale.

Scale != complexity. It’s not about service providers and enterprises. It doesn’t matter if Google’s problems are not your problems; borrowing from the hyperscale is not a “bad thing.” It’s just a “thing.” Think clearly about the problem set, understand the problem set, and borrow liberally. There is no such thing as a “service provider technology,” nor is there any such thing as an “enterprise technology.” There are problems, and there are solutions. To be an engineer is to connect the two.