One of the hands-on exercises in our Networking in Public Cloud Deployments online course asks the attendees to deploy a full-blown virtual networking solution with a front-end (web) server in a public subnet, and back-end (database) server in a private subnet.

The next (optional) exercise asks them to add IPv6 to the mix for a full-blown dual-stack deployment.

Two weeks ago I started with a seemingly simple question:

If a BGP speaker R is advertising a prefix A with next hop N, how does the network know that N is actually alive and can be used to reach A?

… and answered it for the case of directly-connected BGP neighbors (TL&DR: Hope for the best).

Jeff Tantsura provided an EVPN perspective, starting with “the common non-arguable logic is reachability != functionality”.

Now let’s see what happens when we add route reflectors to the mix. Here’s a simple scenario:

We started March 2020 with the second part of Cisco SD-WAN webinar by David Peñaloza Seijas, continued with Upcoming Internet Challenges update, and concluded with 400 GE presentation by Lukas Krattiger and Mark Nowell.

You can access all these webinars with Standard or Expert ipSpace.net subscription. The Cisco SD-WAN presentation is already available with free ipSpace.net subscription, which will also include the edited 400 GE videos once we get them back from our video editor.

Git is great (once you get beyond the basic recipes), and I love my new blog setup that allows me to keep track of all the changes I make with Git.

However, there’s a slight gotcha if you use Git with Markdown: whenever you change something, the whole line (and using tools like IA Writer a whole paragraph is a single line) is marked as changed, for example:

Adrian Giacometti described how he used Elastic Stack (ELK) to build a dashboard for his integration tests and network logs.

Maybe it’s time to build our own network monitoring systems from open-source components instead of paying vendors big bucks for slick PowerPoint slides.

David Penaloza decided to demystify Cisco’s SD-WAN, provide real world experience beyond marketing hype, and clear confusing and foggy messages around what can or cannot be done with Cisco SD-WAN.

He started the first part of his Cisco SD-WAN Foundations and Design Aspects webinar with a quick look beneath the surface of shiny marketing and corporate slidess.

One of the attendees of my Building Network Automation Solutions online course quickly realized a limitation of Ansible (by far the most popular network automation tool): it stores all the information in random text files. Here’s what he wrote:

I’ve been playing around with Ansible a lot, and I figure that keeping random YAML files lying around to store information about routers and switches is not very uh, scalable. What’s everyone’s favorite way to store all the things?

He’s definitely right (and we spent a whole session in the network automation course discussing that).

Let’s agree for a millisecond that you can’t find any other way to migrate your workload into a public cloud than to move the existing VMs one-by-one without renumbering them. Doing a clumsy cloud migration like this will get you the headaches and the cloud bill you deserve, but that’s a different story. Today we’ll talk about being clumsy the right and the wrong way.

There are two ways of solving today’s challenge:

Jeff Tantsura published a great response to my Can We Trust BGP Next Hops blog post on LinkedIn, and I asked him for permission to save it in a more permanent form. Here it is (slightly edited)…

I’d like to bring back EVPN context. The discussion is more nuanced, the common non-arguable logic here - reachability != functionality.

Numerous online companies are using the COVID-19 crisis to make their products better known (PacketPushers collected some of them). Nothing wrong with that - they’re investing into providing free- or at-cost resources, and hope to get increased traction in the market. Pretty fair and useful.

Then there are others… Here’s a recent email I got: