Webinars in May 2020

Being stuck at home like most everyone else we’re continuing the increased pace of content production in May 2020:

• I’ll continue the Introduction to Containers and Docker update. We got through the basics the last time and will cover Linux namespaces and how Docker uses them on May 5th.
• We finally found an independent guest speaker familiar with Cisco ACI. Mario Rosi will start the Cisco ACI series with an introductory webinar on May 12th.
• Dinesh Dutt will continue his Network Automation Tools update on May 19th.
• Hoping to get through Introduction to Docker on May 5th, I plan to do a deep dive into Docker Networking on May 26.
• Finally, I’m positive I won’t cover all the bridging and routing material I created in today’s webinar, so we’ll continue with routing protocol basics on May 28th.

Network Automation and Hammer of Thor

Imagine that you just stumbled upon the hammer Thor carelessly dropped, and you’re so proud of your new tool that everything looks like a nail even though it might be a lightbulb or an orange.

That happens to some people when they get the network automation epiphany: all of a sudden CLI and manual configuration should be banned, and everything can be solved by proper incantation of Git and Ansible commands or whatever other workflow you might have set up… even though the particular problem might have nothing to do with what you have just automated.

MUST READ: When Programming a System with High Kinetic Energy

Kode Vicious (aka George V. Neville-Neil ) wrote another brilliant article on reducing risk in systems that can do serious harm. Here are just two of the gems:

The risks involved in these systems come from three major areas: marketing, accounting, and management.

There is a wealth of literature on safety-critical systems, much of which points in the same direction: toward simplicity. With increasing complexity comes increasing risk …

For whatever reason most networking- and virtualization vendors joined a lemming-like run in the opposite direction years ago.

Interview: Impact of COVID-19 on Networking Engineers and Public Cloud

Ben Friedman and his team (the video crew producing all the Tech Field Day events) published a number of interviews about the impact of COVID-19 on IT.

Among other things we discussed how busy networking engineers are trying to cope with unexpected demand, and how public cloud isn’t exactly infinitely elastic.

Overlay Networking with Ouroboros on Software Gone Wild

This podcast introduction was written by Nick Buraglio, the host of today’s podcast.

As private overlays are becoming more and more prevalent and as SD-WAN systems and technologies advance, it remains critical that we continue to investigate how we think about internetworking. Even with platforms such as Slack Nebula, Zerotier, or the wireguard based TailScale becoming a mainstream staple of many businesses, the question of “what is next” is being asked by an ambitious group of researchers.

Can We Trust Server DSCP Marking?

A reader of my blog sent me this question:

Do you think we can trust DSCP marking on servers (whether on DC or elsewhere - Windows or Linux )?

As they say “not as far as you can throw them”.

Does that mean that the network should do application recognition and marking on the ingress network node? Absolutely not, although the switch- and router vendors adore the idea of solving all problems on their boxes.

Deploying IPv6 in Public Clouds is Easy

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.

Can We Trust BGP Next Hops (Part 2)?

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:

March 2020 on ipSpace.net

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 Tip: Use Word Diff

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:

Interesting: Easy Analytics with Elastic Stack

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.

Video: Going Beneath the Cisco SD-WAN Surface

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.

Growing Beyond Ansible host_vars and group_vars

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).

When All You Have Are Stretched VLANs…

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:

Response: Next-Hop and VTEP Reachability in EVPN Networks

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.

COVID-19 Profiteers?

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:

Video: Networks Are (Not) Secure

It’s amazing how many people still believe in Security Fairy (the mythical entity that makes your application magically secure), fueling the whole industry of security researchers who happily create excruciatingly detailed talks of how you can use whatever security oversight to wreak havoc (even when the limitations of a technology are clearly spelled out in an RFC).

In the Networks Are Not Secure (part of How Networks Really Work webinar) I described why we should never rely on network infrastructure to provide security, but have to implement it higher up in the application stack.

NetDevOps Automation with REST API

Andrea Dainese added REST (Web) API to his Automation for Cisco NetDevOps article. You might love his explanation of the screen scraping methods used by legacy implementations. He was too polite to throw around any names, but I could immediately think of NETCONF or RESTCONF implementation on Cisco IOS.

Building BGP Route Reflector Configuration with Ansible/Jinja2

One of our subscribers sent me this email when trying to use ideas from Ansible for Networking Engineers webinar to build BGP route reflector configuration:

I’m currently discovering Ansible/Jinja2 and trying to create BGP route reflector configuration from Jinja2 template using Ansible playbook. As part of group_vars YAML file, I wish to list all route reflector clients IP address. When I have 50+ neighbors, the YAML file gets quite unreadable and it’s hard to see data model anymore.

Whenever you hit a roadblock like this one, you should start with the bigger picture and maybe redefine the problem.

Can We Trust BGP Next Hops (Part 1)?

Aldrin sent me an interesting question as a comment to one of my EVPN blog posts:

How does the network know that a VTEP is actually alive? (1) from the point of view of the control plane and (2) from the point of view of the data plane? And how do you ensure that control and data plane liveness monitoring has the same view? BFD for BGP is a possible solution for (1) but it’s not meant for 3rd party next hops, i.e. it doesn’t address (2).

Let’s stop right there (or you’ll stop reading in the next 10 milliseconds). I will also try to rephrase the question in more generic terms, hoping Aldrin won’t mind a slight detour… we’ll get back to the original question in another blog post.