The early October 2021 Facebook outage generated a predictable phenomenon – couch epidemiologists became experts in little-known Bridging the Gap Protocol (BGP), including its Introvert and Extrovert variants. Unfortunately, I also witnessed several unexpected trips to Mount Stupid by people who should have known better.

To set the record straight: everyone’s been there, and the more vocal you tend to be on social media (including mailing lists), the more probable it is that you’ll take a wrong turn and end there. What matters is how gracefully you descend and what you’ve learned on the way back.

When I started creating the How Networks Really Work series, I wondered whether our subscribers (mostly seasoned networking engineers) would find it useful. Turns out at least some of them do; this is what a long-time subscriber sent me:

How Networks Really Work is great, it’s like looking from a plane and seeing how all the roads are connected to each other. I know networking just enough to design and manage a corporate network, but there are many things I have learned, used and forgotten along the way.

Two weeks ago I replied to a battle-scar reaction to 7-layer OSI model, this time I’ll address a much more nuanced view from Russ White. Please read his article first (as always, it’s well worth reading) and when you come back we’ll focus on this claim:

The OSI Model does not accurately describe networks.

Like with any tool in your toolbox, you can view the 7-layer OSI model in a number of ways. In the case of OSI model, it can be used:

I should have known better, but I got pulled into another stretched VLANs for disaster recovery tweetfest. Surprisingly, most of the tweets were along the lines of you really shouldn’t be doing that and that would never work well, but then I guess I was only exposed to a small curated bubble of common sense… until this gem appeared in my timeline:

Interestingly, that’s exactly how IP works:

One of my readers sent me this interesting question:

It begs the question in how far graduated students with a degree in computer science or applied IT infrastructure courses (on university or college level or equivalent) are actually aware of networking fundamentals. I work for a vendor independent networking firm and a lot of my new colleagues are college graduates. Positively, they are very well versed in automation, scripting and other programming skills, but I never asked them what actually happens when a packet traverses a network. I wonder what the result would be…

I can tell you what the result would be in my days: blank stares and confusion. I “enjoyed” a half-year course in computer networking that focused exclusively on history of networking and academic view of layering, and whatever I know about networking I learned after finishing my studies.

I was speaking with a participant of an SDN event in Zurich after the presentations, and he made an interesting comment: whenever he experienced serious troubleshooting problems in his career, it was due to lack of understanding of networking fundamentals.

Let me give you a few examples: Do you know how ARP works? What is proxy ARP? How does TCP offload work and why is it useful? What is an Ethernet collision and when would you see one? Why do we need MLD in IPv6 neighbor discovery?

netlab release 26.10 adds new SRv6 implementations and features:

• Full SRv6 support (IS-IS, layer-3 services, L3VPN) on Junos
• SRv6 with IS-IS and SRv6 layer-3 services on Nokia SR Linux
• IPv4 layer-3 services with SRv6 locators exchanged over EBGP on FRRouting and Cisco IOS XR

Other new features include:

• Generic prefix sets for static routes
• containerlab nodes can start in batches or wait for other nodes to start.
• netlab install netmiko installs the Netmiko and Paramiko packages needed for Netmiko-based device configuration and helps you change the device configuration mode for supported devices.

Chris Siebenmann publishes articles written from an interesting perspective: he’s a Unix herder at a university (based on my ancient, similar experience, that’s usually worse than herding cats).

In one of his recent articles, he applied the desire paths ideas to IT: don’t fight how people are doing things; either kindly nudge them in the right direction, or help them get stuff done the way they like to get it done, but in the least harmful way. I could definitely use some of his wisdom decades ago 🤷🏻‍♂️.

I wanted to make my SRv6 lab examples usable with more platforms. Adding netlab Junos SRv6 support (included in the 26.10 release) was relatively easy; here’s what I learned while working on the pull request:

Andre Toonk published yet another Internet-measuring tool: watchthenet.com tries to ping every IPv4 address every few hours (probing every /24 every 49 seconds), resulting in a rapidly updated state of the Internet. If an ISP has a bad hair day, Andre knows within minutes.

Make sure you bookmark his website and read his blog post for more details.