What, really, is “technical debt?” It’s tempting to say “anything legacy,” but then why do we need a new phrase to describe “legacy stuff?” Even the prejudice against legacy stuff isn’t all that rational when you think about it. Something that’s old might also just be well-tested, or well-worn but still serviceable. Let’s try another tack.

Technical debt, in the software world, can be defined as working on a piece of software for long periods of time by only adding features, and never refactoring or reorganizing the code to meet current conditions. The general idea is that as new features are added on top of the old, two things happen. First, the old stuff becomes a sort of opaque box that no-one understands. Second, the stuff being added to the old increasingly relies on public behavior that might be subject to unintended consequences or leaky abstractions.

To resolve this problem in the software world, software is “refactored.” In refactoring, every use of a public API is examined, including what information is being drawn out, or what the expected inputs and outputs are. The old code is then “discarded,” in a sense, and a new underlying function written that meets the requirements discovered in the existing codebase. The refactoring process allows the calling functions and called functions, the clients and the servers, to “move together.” As the overall understanding of the system changes, the system itself can change with that understanding. This brings the implementation closer to the understanding of the current engineering team.

So technical debt is really the mismatch between the understanding of the current engineering team imposed onto the implementation of a prior engineering team with a different understanding of the requirements (even if the older engineering team is the same people at a different time).

How can we apply this to networking? In the networking world, we actively work against refactoring by future proofing.

Future proofing: building a network that will never need to be replaced. Or, perhaps, never needing to go to your manager and say “I need to buy new hardware,” because the hardware you bought last week does not have the functionality you need any longer. This sounds great in theory, but the problem with theory is it often does not hold up when the glove hits the nose (every has a plan until they are punched in the face). The problem with future proofing is you can’t see the punch that’s coming until the future actually throws it.

If something is future proofed, it either cannot be refactored, or there will be massive resistence to the refactoring process.

Maybe its time we tried to change our view of things so we can refactor networks. What would refactoring a network look like? Maybe examining all the configurations within a particular module, figuring what they do, and then trying to figure out what application or requirement led to that particular bit of configuration. Or, one step higher, looking at every protocol or “feature” (whatever a feature might be), figuring out what purpose it might serve, and then intentionally setting about finding some other way, perhaps a simpler way, to provide that same service.

One key point in this process is to begin by refusing to look at the network as a set of appliances, and starting to see it as a system made up of hardware and software. Mentally disaggregating the software and hardware can allow you to see what can be changed and what cannot, and inject some flexibility into the network refactoring process.

When you refactor a bit of code, what you typically end up with a simpler piece of software that more closely matches the engineering team’s understanding of current requirements and conditions. Aren’t simplicity and coherence goals for operational networks, too?

If so, ehen was the last time you refactored your network?

1 Comment

  1. Random Short Take #46 | PenguinPunk.net on 12 November 2020 at 2:00 pm

    […] really enjoyed this piece from Russ on technical debt, and some considerations when thinking about we can […]