When I first heard that OSPFv3 introduced even more link-state advertisement (LSA) types, I despaired. As if the original seven didn’t take us long enough to memorise! Then I actually learned what they do – and honestly, it’s hard to imagine why we ever did it any differently. Let’s learn about them together!Read more
A little while ago, I was mucking about with some EIGRP authentication in a lab. Because when I party, I party hard. Rock and roll is an integral part of my soul. Anyway, EIGRP was running. Neighbors were formed. And then I added a keychain, and applied it to my interfaces. The neighborship dropped, tried to re-establish – and failed. Why? Let’s find out!Read more
Big-ups to the designers of OSPF for giving very similar names to two totally different things. In this post, we clarify the difference between stub areas and stub networks.Read more
When you’re first getting to grips with your router’s OSPF database, you might see mention of something called a “stub network”. And let me tell you: never before have I seen a phrase so clumsily defined. Let’s take a look, and find out what a stub network actually is.Read more
Stub areas are a very easy concept to understand, but it comes with a ton of specific jargon that can make it super-daunting. So, in this post I’ll take time to explain these concepts, and to define just enough jargon to make you feel like you’re part of the elite. We’ll take it slow, like new lovers, or someone cooking an expensive turkey.Read more
When you’re configuring a router for IPv6, what subnet mask should you use on your point-to-point links?
I’ve seen some people use /64s, I’ve seen other people using /127s – and even subnet masks in between. Do any of these people know what they’re doing? Almost certainly not. But hey, that doesn’t mean we can’t work out the pros and cons of both subnet masks – because it turns out that the question of which one to use is actually a bit tricky.
If you’re cool, hip, and “with it”, you’ll know there’s one thing millennials just can’t stop talking about: MPLS VPNs. But: how do you configure them? Well, it’s a good job you came to me – because in this article you’ll learn exactly how. We’ll configure it together, we’ll type some show commands to learn exactly what’s going on – and then we’ll look at how to troubleshoot it when it breaks.Read more
Something that took me ages to grasp was the difference between BGP route-distinguishers and route-targets in MPLS VPNs. And even when I thought I understood, I still didn’t see why we needed both. Why not just have the one number to fit both tasks? Click this post, and find out all about it!Read more