Blog Posts in April 2021
Who would have thought that you could get better at what you do by figuring out how things you use really work. I probably made that argument (about networking fundamentals) too many times; Julia Evans claims the same approach applies to programming.
I thought I was snarky and somewhat rude (and toned down some of my blog posts on second thought), but I’m a total amateur compared to Corey Quinn. His last masterpiece – Machine Learning is a Marvelously Executed Scam – is another MUST READ.
Years ago I wrote a series of blog posts comparing transparent bridging and IP routing, and creating How Networks Really Work materials seemed like a perfect opportunity to make that information more structured, starting with Transparent Bridging Fundamentals.
One of my readers wondered whether it makes sense to buy low-latency switches from Cisco or Juniper instead of switches based on merchant silicon like Trident-3 or Jericho (regardless of whether they are running NX-OS, Junos, EOS, or Linux).
As always, the answer is it depends, but before getting into the details, let’s revisit what latency really is. We’ll start with a simple two-node network.
TL&DR: If you happen to like working with containers, you could use netsim-tools release 0.5 to provision your container-based Arista EOS labs.
Why does it matter? Lab setup is blindingly fast, and it’s easier to integrate your network devices with other containers, not to mention the crazy idea of running your network automation CI pipeline on Gitlab CPU cycles. Also, you could use the same netsim-tools topology file and provisioning scripts to set up container-based or VM-based lab.
Some networking engineers breeze through our Network Automation online course, others disappear after a while… and a few of those come back years later with a spectacular production-grade solution.
Stephen Harding is one of those. He attended the automation course in spring 2019 and I haven’t heard from him in almost two years… until he submitted one of the most mature data center fabric automation solutions I’ve seen.
Not only that, he documented the solution in a long series of must-read blog posts. Hope you’ll find them useful; I liked them so much I immediately saved them to Internet Archive (just in case).
One of my readers sent me a series of “how do I get started with…” questions including:
I’ve been doing networking and security for 5 years, and now I am responsible for our cloud infrastructure. Anything to do with networking and security in the cloud is my responsibility along with another team member. It is all good experience but I am starting to get concerned about not knowing automation, IaC, or any programming language.
No need to worry about that, what you need (to start with) is extremely simple and easy-to-master. Infrastructure-as-Code is a simple concept: infrastructure configuration is defined in machine-readable format (mostly text files these days) and used by a remediation tool like Terraform that compares the actual state of the deployed infrastructure with the desired state as defined in the configuration files, and makes changes to the actual state to bring it in line with how it should look like.
Here’s an interesting fact: cloud-based stuff often refuses to die; it might become insufferably slow, but would still respond to the health checks. The usual fast failover approach used in traditional high-availability clusters is thus of little use.
For more details, read the Fail-Fast is Failing… Fast ACM Queue article.
Ansible and Jinja2 are not an ideal platform for data manipulation, but sometimes it’s easier to hack together something in Jinja2 than writing a Python filter. In those cases, you might find the Data Model Transformation with Jinja2 by Philippe Jounin extremely useful.
As I started Software Gone Wild podcast in June 2014, I wanted to help networking engineers grow beyond the traditional networking technologies. It’s only fitting to conclude this project almost seven years and 116 episodes later with a similar theme Avi Freedman proposed when we started discussing podcast topics in late 2020: how do we make networking attractive to young engineers.
I was listening to an excellent container networking podcast and enjoyed it thoroughly until the guest said something along the lines of:
With Kubernetes networking policy, you no longer have to be a networking expert to do container network security.
That’s not even wrong. You didn’t have to be a networking expert to write traffic filtering rules for ages.
A junior networking engineer asked me for a list of recommended entry-level networking blogs. I have no idea (I haven’t been in that position for ages); the best I can do is to share my list of networking-related RSS feeds and the process I’m using to collect interesting blogs:
- RSS is your friend. Find a decent RSS reader. I’m using Feedly – natively in a web browser and with various front-ends on my tablet and phone (note to Google: we haven’t forgotten you killed Reader because you weren’t making enough money with it).
- If a blog doesn’t have an RSS feed I’m not interested.
A while ago, someone made a remark on my suggestions that networking engineers should focus on getting fluent with cloud networking and automation:
The running thing is, we can all learn this stuff, but not without having an opportunity.
I tend to forcefully disagree with that assertion. What opportunity do you need to test open-source tools or create a free cloud account? My response was thus correspondingly gruff:
Last week I described the new features added to netsim-tools release 0.4, including support for unnumbered interfaces and OSPF routing. Now let’s see how I used them to build a multi-vendor lab to test which platforms could be made to interoperate when running OSPF over unnumbered Ethernet interfaces.
I needed to define an unnumbered addressing pool first:
addressing: core: unnumbered: true
I wanted to run OSPF on all devices in the lab:
module: [ ospf ]
Have you ever wondered what the Kubernetes fuss is all about? Why would you ever want to use it? Stuart Charlton tried to answer that question in the introduction part of his fantastic Kubernetes Networking Deep Dive webinar.
It’s almost exactly three months since I announced ipSpace.net going on an extended coffee break. We had some ideas of what we plan to do at that time, but there were still many gray areas, and thanks to tons of discussions I had with many of my friends, subscribers, and readers, they mostly crystallized into this:
You’re trusting me to deliver. We added a “you might want to read this first” warning to the checkout process, and there was no noticeable drop in revenue. Thanks a million for your vote of confidence!