routing

JUNOS: CHASSIS CLUSTERS – A BEGINNERS GUIDE TO JUNIPER SRX HIGH AVAILABILITY

March 3, 2018January 29, 2019 Chris 8432 Views 11 Comments

Want to learn how to configure Chassis Cluster, which lets you configure high-availability failover on Juniper firewalls? Good luck with the official documentation – it weighs in at precisely 638 pages long. 638 pages! That’s the length of two good books! Or one badly edited one. Anyway, this article is my attempt at boiling those 638 pages down into something a bit more manageable. You can thank me by emailing me £700,000.

ipv6 ospf ospfv3 routing

OSPFv3 – HOW TO READ IPv6’s OSPF DATABASE

January 5, 2018October 20, 2018 Chris 1425 Views 0 Comments

Once you’ve read my guide to the new link-state advertisement types in OSPFv3, give this post a read, where we take a deep-deep into the OSPFv3 database. Put your topology hat on: we’re going exploring.

ipv6 ospf ospfv3 routing

OSPFv3: THE NEW LSA TYPES IN IPv6 OSPF

January 5, 2018October 20, 2018 Chris 682 Views 0 Comments

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!

authentication eigrp routing troubleshooting

EIGRP: TROUBLESHOOT AUTHENTICATION USING THE SHOW KEY CHAIN COMMAND

December 11, 2017October 20, 2018 Chris 580 Views 0 Comments

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!

ospf routing

OSPF: STUB AREAS VS STUB NETWORKS: WHAT IS THE DIFFERENCE?

December 6, 2017October 20, 2018 Chris 518 Views 0 Comments

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.

ospf routing

OSPF: WHAT IS A STUB NETWORK?

December 6, 2017October 20, 2018 Chris 1434 Views 0 Comments

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.

ospf routing

OSPF: WHAT IS A STUB AREA?

December 6, 2017October 20, 2018 Chris 754 Views 0 Comments

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.

ipv6 routing subnetting

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

November 28, 2017October 20, 2018 Chris 2041 Views 1 Comment

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.

bgp gns3 topologies mpls routing vpn

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

November 22, 2017October 20, 2018 Chris 1165 Views 0 Comments

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.

bgp mpls routing vpn

BGP / MPLS: ROUTE DISTINGUISHERS vs ROUTE TARGETS: WHAT ARE THEY? WHY DO WE NEED THEM BOTH?

November 20, 2017October 20, 2018 Chris 1475 Views 1 Comment

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!