Archive for 2021

I sometimes reference Keith’s Law in my teaching, but I don’t think I’ve ever explained it. Keith’s Law runs something like this:

Any large external step in a system’s capability is the result of many incremental changes within the system.

The reason incremental changes within a system appear as a single large step to outside observers is the smaller changes are normally hidden by abstraction. This is, in fact, the purpose of abstraction—to hide small changes inside a system from external view. Keith’s law is closely related to Clarke’s third law that “Any sufficiently advanced technology is indistinguishable from magic.” What looks like magic from the outside is really just a bunch of smaller things—each easier to understand on its own—combined into one single “thing” through abstraction.
If you’ve read this far, you’re probably thinking—what does this have to do with network engineering?
Well, several things, really.

First—the network is just an abstraction that moves packets to its users. Moving packets seems so … simple … to network users. You put data in here, and data comes out over there. All the little stuff that goes into making a network work are lost in the abstraction of the virtual connection between two hosts.

If you want users to understand why building a network is hard, you’re going to have to work hard at it. And you’re not likely to succeed—it’s often better just to live with the reality that users aren’t going to understand. Of course, this isn’t necessarily a bad thing, at least until it’s time to buy hardware and software to make all this magic work.

Second—no-one outside the network is ever going to understand the refactoring, simplification, and new features you’re trying to build into the network on their own. Users will only understand these things when they are related to some bigger picture, something they can see beyond the abstraction the network presents.

If you’re going to justify doing new things, you need to do so in terms of “larger things,” things that can be seen from outside the abstraction.

Third—no-one is going to pat you on the back for all the little things that need to be done to deploy a new major service. From the outside, that new service, or new cost savings, or whatever—it’s all just indistinguishable from magic.

Keith’s law is both good and bad. But it also means you need to learn how to frame your work in a way that users, who don’t have access to the inner workings of the network, can understand why you’re doing what you’re doing.

Turning this around, this also means you shouldn’t accept the “magic” of vendor products. That brilliant new capability your vendor is showing you is really made up of a lot of smaller components. The abstraction is just that—an abstraction. If you really want to understand the positive and negative consequences of deploying something new, you need to look beyond the abstraction.