On Using the Right Word

A while back, I was sitting in a meeting where the presenter described switching from a “traditional, hierarchical data center fabric” to a spine-and-leaf (while drawing CLOS, in all capital letters, on the whiteboard). He pointed out that the spine-and-leaf design is simpler because it only has two tiers rather than three.

There is so much wrong with this I almost winced in physical pain. Traditional hierarchical designs are not fabrics. Spine-and-leaf fabrics are not CLOS, but Clos, fabrics. Clos fabrics have three stages, not two—even if we draw them “folded” so you only see two apparent levels to the fabric. In fact, all spine-and-leaf fabrics always have an odd number of stages, and they are stages, not tiers.

More recently, I heard someone talking about an operating system that was built using microservices. I thought—“that would be at neat trick.” To build something with microservices does not just mean a piece of software using modules—this would be modular application (or operating system) design. Microservices architectures break the application up into the most basic components possible and then scale each kind of component out (rather than up) by spinning new copies of each service as needed. I cannot imagine scaling an operating system out by spinning multiple copies of the same service, and then providing some sort way to spread load across the various copies. Would you have some sort of anycast IPC? An internal DNS server or load balancer?

You can have an OS that natively participates in a larger microservices-based architecture, but what would microservices within the operating system look like, precisely?

Maybe my recent studies in philosophy make me much more attuned to the way we use language in the network engineering world—or maybe I’m just getting old. Whatever it is, our determination to make every word mean everything is driving me nuts.

What is the difference between a router and a switch? There used to be a simple definition—routers rewrite the L2 header and switches don’t. But now that routers switch packets, and switches route packets, the only difference seems to be … buffer depth? Feature set? The line between router and switch is fuzzy to the point of being meaningless, leaving us with no real term to describe a real switch any longer (a device that doesn’t do routing).

What about software defined networks? We’ve been treated to software defined everything now, of course. And intent? I get the point of intent, but we’re already moving down the path of making the meaning so broad that it can even contain configuring the CLI on an old AGS+. And don’t get me started on artificial intelligence, which is often learned to describe something closer to machine learning. Of course machine learning is often used to describe things that are really nothing more than statistical inference.

Maybe it’s time for a general rebellion against the sloppy use of language in network engineering. Or maybe I’m just tilting at yet another windmill. Wake me up when we’ve gotten to the point that we can use any word interchangeably with any other word in the network engineering dictionary. I await the AI that routes packets by reading your mind (through intent) called a swouter… or something.


  1. Karsten on 9 March 2021 at 4:25 am

    We still have a word for switches, that are only “switching”. It is called a (multi-port) bridge 😉
    But I don’t believe anyone will use that word again.