N4N064: A Gentle Introduction to Border Gateway Protocol (BGP)

Holly Podbilak (0:07)

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Ethan Banks (0:17)

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Holly Podbilak (0:30)

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Ethan Banks (0:39)

Welcome to N is for Networking. I'm Ethan Banks with Holly Podbilak. Holly and I have intergenerational networking discussions. She is a modern networker, having to learn all this complicated networking tech we've been building for decades, and I got started with networking when it was just taking off in the mid 1990s before switches were much of a thing and where whether or not you have a dedicated internet connection to your business. That was like a hard decision people had to make back then. Well, together Holly and I explore networking in the modern era with an eye to the past to help us understand why we've got what we've got. And today, it's here. We're gonna do a gentle introduction to BGP, the routing protocol of the global internet. And here in 2026, BGP is finding uses in all sorts of places everywhere, not just for internet routing.

I'd say it's hard to get away from BGP, and it is such a huge topic. Large books have been written about BGP and the related technologies that fall into BGP's orbit.

And so if you're new to this topic, that can make BGP intimidating because there's just so much information. But we are here to get you started with, again, a truly gentle introduction to Border Gateway protocol. Okay, Holly, so before we hit record, you and I were talking and you're like, oh, we're going to do this topic. And you're just like, I just, you just don't want to.

Holly Podbilak (2:04)

So why?

Ethan Banks (2:05)

Why is BGP a thing that intimidates you?

Holly Podbilak (2:07)

I mean, I want to do the topic, but I just feel like it's such a huge, it's just such a huge topic to conquer. And I also, in my experience, I know that I've only scratched the very surface level of BGP. I never got around to implementing it because I didn't really deal with any large enough companies, and also no one's implementing BGP for the first time, typically.

So there's just a lot of, not gray area, but unknowns. And I know all the things that come with BGP, and it's a scary topic for me.

Ethan Banks (2:44)

Yeah, and honestly, it's a little bit intimidating for me. And I had to know BGP at a CCIE level back in 2008, when I did my CCIE exam. And since then, so much has been added to BGP, and what it does, and what its capabilities are, just in that timeframe coming up on 20 years here. We've added BGP so that it works in a data center. BGP so that it does EVPN, VXLAN now is the control plane. We've added BGP flow spec. These were all things that I never had to learn back in the day, even though once upon a time, I knew BGP at what was considered an expert level. And so it's a little, it was a lot then, it's a lot more now. So you're not wrong that BGP has got an overwhelming amount of information around it. So, okay, everyone, in this episode, we are not going to get into a lot of nuts and bolts and super details and how to configure and all of that. This is going to be an overview, like a survey of BGP as a topic, just to give you some background, what it is, how it fits into the world. And we'll do some other shows over time. We're not going to do this epic back to back to back to back series on BGP, but we are going to cover in more detail over time. And at the end of the show, we'll talk about what some of those topics are we're going to hit. So Holly, let's start at the beginning here. We want to just introduce BGP. What is this thing? And first of all, we said it's Border Gateway Protocol, not Bridging Gap Protocol. Do you know what that reference is, the Bridging Gap Protocol joke? No. It came out on some kind of a news story here recently where there was some internet outage and it was reported as the Bridging Gap Protocol on the internet broke or something like that, whatever it was. So if you see any memes about Bridging Gap Protocol, that's what that was. It's not that. It's Border Gateway Protocol. And we're using BGP version 4