A lot of people are confused about the roles of network layers (some more than others), the interactions between MAC addresses, IP addresses, and TCP/UDP port numbers, the differences between routing and bridging… and why it’s so bad to bridge across large distances (or in large networks).

I tried to explain most of those topic in How Networks Really Work webinar (next session coming on April 2nd), but as is usually the case someone did a much better job: you MUST READ the poetic and hilariously funny World in which IPv6 was a good design by Avery Pennarun.

A reader of my blog was “blessed” with hands-on experience with SD-WAN offered by large service providers. Based on that experience he sent me his views on whether that makes sense. Enjoy ;)

We all have less-than-stellar opinions on service providers and their offerings. It is well known that those services are expensive and usually lacking quality, experience, or simply, knowledge. This applies to regular MPLS/BGP techniques as to - currently, the new challenge - SD-WAN.

One of the attendees of our Building Network Automation Solutions online course asked an interesting question in the course Slack team:

Has anyone wrote a playbook for putting a circuit into maintenance mode — i.e. adjusting metrics to drain traffic away from a circuit that is going to be taken down for maintenance?

As always, you have to figure out what you want to do before you can start automating stuff.

Found this “gem” describing the differences between layer-2 and layer-3 on an unnamed $vendor web site.

Layer 2 is mainly concerned with the local delivery of data frames between network devices on the same network or local area network (LAN).

So far so good…

Years ago I figured out that I’d eventually have to migrate my blog from Blogger to something more independent, and based on my previous experience with Wordpress I wasn’t exactly enthusiastic to go down that path.

In 2015 I’ve seen Scott Lowe going from Wordpress to Jekyll and then to Hugo, and decided it might make sense to recreate ipSpace.net blog with a tool that generates static web pages… but never found the time to do it.

Defining service availability using the famous X nines (and all the hacks like “planned downtime doesn’t count”) is pretty useless in a highly distributed system where the only thing that really matters is the user experience, not ping response times. One should ask what precisely should we be measuring, and how could we make sure we can act on the measurements

More details in a concise analysis of the Meaningful Availability paper by the one-and-only The Morning Paper.

After describing the FRRouting architecture, as well as recent performance optimizations and usability enhancements, Donald Sharp concluded the FRRouting webinar with detailed deployment guidelines.

One of the first roadblocks you’ll hit in your “let’s master Ansible” journey will be a weird error deep inside a Jinja2 template. Can we manage that complexity somehow… or as one of the participants in our Building Network Automation Solutions online course asked:

Is there any recommendation/best practices on Jinja templates size and/or complexity, when is it time to split single template into function portions, what do you guys do? And what is better in terms of where to put logic - into jinja or playbooks

One of my friends described the challenge as “Debugging Ansible is one of the most terrible experiences one can endure…” and debugging Jinja2 errors within Ansible playbooks is even worse, but there are still a few things you can do.

As the last part of his network automation journey, Anne Baretta described the automation tools he used.

Notes

• We covered numerous automation tools (including the ones Anne used) in our Building Network Automation Solutions online course;
• For an overview of automation tools, watch the Network Automation Tools webinar.

Johannes Weber published a PCAP file containing samples of over 50 different L2 - L7 protocols. Enjoy ;)