BGP study guides tell you that loopback-to-loopback EBGP session require a TTL of 2 or more. The trouble is, they rarely say why. This leads new students to come to some very incorrect assumptions about how the TTL field works in IP. In fact though, you can absolutely have a TTL of 1! In this post we clear up all the confusion – and we even look at how you can use a TTL of 255 to bring extra security to your network.
The fourth part in this intro to IS-IS series tackles areas, and how they’re different to levels. A lot of new students confuse them, and a lot of documentation gets it wrong too! This post clears everything up for you, and will make you super confident. You’ll also learn about IS-IS default routes, and route leaking from L2 to L1. Give it a click!
Some ISPs like to remove point-to-point prefixes from IS-IS. This keeps their routing tables small and easier to read. But how does it work? Doesn’t this break things? What are the trade-offs? This post shows you how to configure this solution, and the things you’ll want to consider if you deploy it. It’s super-cool, and you’ll definitely enjoy seeing the mechanics in action!
In this post we show how to configure RSVP in Junos – and then we roll up our sleeves to look at some packet captures of the PATH and RESV messages on the wire. There’s some mighty fine learning in this post!
I recently received an email from someone asking if I knew a good complete beginners guide to MPLS. Their mail inspired me, so I wrote one for them – and now, I’m sharing it with you! If you’ve always wanted to know what MPLS is, click here to fulfill your deepest dreams.
Hey there: you smell good! That’s probably because you just read Part 1 of this two-part blog post, where we learned all about BGP communities, and how route-targets are used in MPLS VPNs. Well, now you know the theory, let’s look at a problem ticket. Click here to read Part 2!