EIGRP: TROUBLESHOOT AUTHENTICATION USING THE SHOW KEY CHAIN COMMAND

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

IPv6 PREFIXES ON POINT-TO-POINT LINKS – /64 OR /127? WHICH SUBNET MASK TO USE?

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.

Read more

MPLS VPN CONFIGURATION – DOWNLOAD FREE GNS3 TOPOLOGY! (CCNP SERVICE PROVIDER)

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