Details and Complexity

What is the first thing almost every training course in routing protocols begin with? Building adjacencies. What is considered the “deep stuff” in routing protocols? Knowing packet formats and processes down to the bit level. What is considered the place where the rubber meets the road? How to configure the protocol.

I’m not trying to cast aspersions at widely available training, but I sense we have this all wrong—and this is a sense I’ve had ever since my first book was released in 1999. It’s always hard for me to put my finger on why I consider this way of thinking about network engineering less-than-optimal, or why we approach training this way.

This, however, is one thing I think is going on here—

The typical program aims to counter the inherent complexity of the decision by providing in-depth information. By providing such extremely detailed and complex information, these interventions try to enable people to make perfect decisions.

We believe that by knowing ever-deeper reaches of detail about a protocol, we are not only more educated engineers, but we will be able to make better decisions in the design and troubleshooting spaces.

To some degree, we think we are managing the complexity of the protocol by “making our knowledge practical”—by knowing the bits, bytes, and configurations. This natural tendency to “dig in,” to learn more detail, turns out to be counterproductive. Continuing from the same article—

The scientific opinion of many psychologists and behavioral scientists suggests the key to time-sensitive decision making in complex and chaotic situations is simplicity, not complexity. Simple-to-remember rules of thumb, or heuristics, speed the cognitive process, enabling faster decisionmaking and action. Recognizing that heuristics have limitations and are not a substitute for basic research and analysis, they nevertheless help break complexity-induced paralysis and support the development of good plans that can achieve timely and acceptable results. The best heuristics capture useful information in an intuitive, easy-to-recall way. Their utility is in assisting decision makers in complex and chaotic situations to make better and timelier decisions.

Knowing why a protocol works the way it does—understanding what it’s doing and why—from an abstract perspective is, I believe, a more important skill for the average network engineer than knowing the bits and bytes—or the configuration.

Abstract correctly—but abstract more. Get back to the basics and know why things work the way they do. It’s easier to fill in the details if you know the how and why.


  1. Pete Welcher on 29 June 2021 at 12:30 pm

    I totally agree.

    I’ll also note that cert tests often seem to be full of trivia, especially stuff like ether type codes (that’s what WireShark is for). Ok, OSPF LSA types and at least some TCP / UDP ports should probably be known. Counter-argument: The former is a weak proxy for understanding how the protocols work, however. And just how many TCP / UDP ports are “well known / should be known”?