FRRouting release 10.6 promised “BGP IPv6 VTEP support,” claiming “it enables EVPN deployments using IPv6 tunnel endpoints while maintaining full backward compatibility with IPv4 VTEPs.” Of course, I had to try it out, and since we already have EVPN over IPv6 running on Arista EOS (since netlab release 26.01), I decided to set up a simple lab with an Arista cEOS device running release 4.35.2F and the latest FRRouting container.

I was not exactly surprised when it did not work. While Arista accepted FRRouting EVPN routes, the FRRouting BGP daemon rejected routes sent by Arista EOS:

In a recent article, Scott Alexander made an interesting point: What AI produces are not hallucinations but shameless guesses (also known as bullshit) because the training process rewards the correct answers but does not penalize the incorrect ones. After all, having an AI model say, “I don’t know that” is not good for business, is it?

On a tangential note, calling those blunders hallucinations was a marketing masterstroke. Not being a native English speaker, I might be missing some nuances, but I feel like hallucinations might be something you’re not responsible for (some of the time), whereas we all know who’s responsible for bullshit and shameless guesses – and responsibility is something the AI companies are clearly trying to stay as far away from as possible.

On another tangential note, if you’re not following Scott Alexander’s blog substack, you’re missing out.

IS-IS was designed to carry node addresses (NSAPs) between level-1 routers (called Intermediate Systems) within an area and area prefixes between level-2 routers, resulting in a perfect separation of concerns and forwarding information summarization. When IETF tried to use the same routing protocol for a networking stack with a completely different addressing mentality, something had to give.

A year ago, I was complaining about SR Linux breaking its configuration data model with a new software release. At that time, I was promised it would only happen once a year, and, like clockwork, that moment arrived with the SR Linux release 26.03.

However, this year Miguel Redondo fixed the netlab SR Linux configuration templates (VRF export policies, LocPref routing policy changes) before I could even start looking at them, and Roman Dodin released a tool that tells you exactly what changed between software releases and how to fix it.

Avery Pennarun published yet another excellent article: every layer of review makes you 10x slower, effectively reiterating what I’ve been saying for decades: all the technology in the world won’t help you unless you re-architect the broken processes.

AI is no exception, but of course, the AI evangelists, LinkedIn AI Wranglers¹, and Thought Leaders will never tell you that (or even admit it).

TL&DR: With the recent changes to online BGP labs, you can also use Aruba CX, Cisco IOS, Cisco IOS XE, Cisco IOS XR, Dell OS10, Junos, or VyOS as external lab devices in most lab exercises (you could always use these devices for the routers you worked on). Previously, you could choose between Arista EOS and FRRouting, both of which are (obviously) still supported.

One of the goals of the Online BGP Labs project was to create an environment in which you could practice the BGP features you were interested in without spending an inordinate amount of time preparing the lab.

For example, if you want to figure out why BGP wedgies work the way they do, you need at least four additional autonomous systems, two of them acting as upstream ISPs for your customer router, and at least one of them implementing BGP policies using BGP communities.

Some netlab users want to accurately replicate their physical network’s topology in a virtual lab. Ignoring the obvious caveats for a moment, the first hiccup is usually the interface naming. All bets are off if you’re using anything but Ethernet in your actual network, but even if you did standardize on Ethernet, the container/VM interface names might not match the physical ones.

netlab provided a solution for a long time – you can specify interface ifindex when attaching a node to a link. For example, use the following topology to connect Ethernet3 on R1 to Ethernet6 on R2:

Geoff Huston published an article supposedly describing the challenge of securing NTP, but as is usually the case, he couldn’t skip the prior art going all the way back (almost) to the formation of Earth.

Before coming to the how do we secure NTP section, you’ll learn everything about the wobbly Earth rotation, the changes in the Earth’s angular speed, the impact of tides, the smearing of leap seconds, the differences between UT1 and UTC, why we use quasars to measure time, and everything there is to know about NTP. Have fun!

The never-ending “we will replace developers” (or networking engineers) pipe dream didn’t start with the latest bout of AI hype (or SDN). As Stephan Schwab explains in his Why We’ve Tried to Replace Developers Every Decade article, it started with COBOL, the magic high-level programming language that businesspeople would use to write their own programs.

At least some of us know how well that ended. I was also unfortunate to be there for the 5GL hype, the forms-driven programming hype, the “everyone will solve every problem out there with Excel macros” (it does work for networking inventory, doesn’t it?), and a few others. So please excuse me if I remain a bit skeptical about the latest fad, even though I find it (like all the previous ones) very useful when used conservatively in limited domains.

I work on a laptop that loves to power down when not used (the right thing to do), which often breaks the SSH session to my netlab server (not so good).

Reconnecting is trivial. Figuring out which lab I was working on and where it lives on the disk after a few hours? That’s the annoying part.

We solved most of that ages ago with the netlab status --all command. It shows all running labs¹ and their directories, so you can quickly jump back to where you were. However, even that gets tedious the 100th time you have to do it.