The Value of Old Ideas


I had a fun exchange on Twitter this week that bears some additional thinking. Emirage (@Emirage6) tweeted a fun meme about learning BGP:

I retweeted it and a few people jumped in the fun, including a couple that said it was better to configure BGP for reasons. This led to a blog post about routing protocols with even more great memes and a good dose of reality for anyone that isn’t a multi-CCIE.

Explain It Like I’m Five

I want you to call your mom and explain BGP to her. Go on and do that now because I’m curious to see how you’d open that conversation. Unless your mom is in networking already I’m willing to bet you’re going to have to start really, really basic. In fact, given the number of news organizations that don’t even know what the letters in the acronym stand for I’d guess you are going to have a hard time talking about the path selection process or leak maps or how sessions are established.

Now, try that same conversation with RIP. I bet it goes a lot smoother. Why? Because RIP is a simple protocol. We don’t worry about prefixes or AS Path prepending or other things when we talk about RIP. Because RIPv1 is the most basic routing protocol you can get. It learns about routes and sends the information on. It’s so simple that you can usually get all of the info about it out of the way in a couple of hours of instruction in a networking class.

So why do we still talk about RIP? It’s so old. Even the second version of the protocol is better. There’s no intelligence. No link state. You can’t even pick a successor route! We should never talk about RIPv1 again in any form, right? So what would you suggest we start with? OSPF? BGP?

The value of RIP is not in the protocol. Instead, the value is in the simplicity of the discussion. If you’ve never heard of a routing protocol before you don’t want to hear about all the complexity of something that runs half the Internet. At least you don’t want to hear about it at first. What you need to hear is how a routing protocol works. That’s why RIP is a great introduction. It does the very minimal basic functions that a routing protocol should do. It learns routes and tells other routers about them.

RIP is also a great way to explain why other routing protocols were developed. We use OPSF and EIGRP and other IGRPs now because RIP doesn’t perform well outside of small networks. There are limitations around IP subnets and network diameter and “routing by rumor” that only make sense when you know how routing protocols are supposed to operate and how they can fall down. If you start with OSPF and learn about link-state first then you don’t understand how a router could ever have knowledge of a route that it doesn’t know about directly or learn about from a trusted source. In essence, RIP is a great first lesson because it is both bad and good.

The Expert’s Conundrum

The other issue at hand is that experts tend to feel like complicated subjects they understand are easy to explain. If that’s the case, then the Explain Like I’m Five Reddit shouldn’t exist. It turns out that trying to explain a complex topic to people without expert knowledge is super hard because they lack the frame or reference you need to help them understand. If you are a network engineer that doesn’t believe me then go ask a friend in the medical profession to explain how the endocrine system works. Don’t make they do a simple explanation. Make them tell you like they’d teach a medical student.

We lose sight of the fact that complex topics can’t be mastered quickly and certain amounts of introductory knowledge need to be introduced to bring people along on the journey. We teach about older models and retired protocols because the knowledge they contain can help us understand why we moved away from them. It also helps us to have a baseline level of knowledge about things that permeate the way we do our jobs.

If we removed things that we never use from the teaching curriculum we’d never have the OSI model since it is never implemented in the pure form in any protocol. We’d teach the TCP/IP model and just tell people that the other things don’t really matter. In fact, they do matter because the pure OSI model takes other things into account that aren’t just focused on the network protocol stack. It may seem silly to us as experts to say that we teach one thing but reality looks much different but that’s how learning works.

We still teach older methods of network topologies like bus and ring even though we don’t use them much any more. We do this because entry-level people need to know why we arrived at the method we use now. Even with the move toward new setups like 3-tier network design and leaf/spine architecture you need to know where Ethernet started to understand why we are where we are today.


Tom’s Take

It’s always important to get a reminder that people are just starting out in the learning process. While it’s easy to be an expert and sit back and claim that iBGP is the best way to approach a routing protocol problem you also have to remember that learners sometimes just need a quick-and-dirty lab setup to test another function. If they’re going to spend hours configuring BGP neighbor relationships instead of just enabling RIP on all router interfaces and moving on to the next part then they’re not learning the right things. Knowledge is important, even if it’s outdated. We still teach RIP and Frame Relay and Token Ring in networking because people need to understand how they operate and why we’ve moved on. They may not ever configure them in practice but they may also never configure BGP either. The value of information doesn’t decrease because it’s old.

1 thought on “The Value of Old Ideas

  1. Summed up in “those who ignore the past are doomed to repeat it”. We teach the past to ensure we continue to move on from it.

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