Javier Antich concluded the AI/ML in Networking webinar with the ugly challenges of using AI/ML in networking. I won’t spoil the fun, you REALLY SHOULD watch the video (keeping in mind he was trying to stay polite and diplomatic).

Every network engineer should be familiar with the DNS basics – after all, all network failures are caused by DNS… unless it’s BGP.

The May 2022 ISP Column by Geoff Huston is an excellent place to brush up on your DNS basics and learn about new ideas, including a clever one to push DNS entries that will be needed in the future to a web client through a DNS-over-HTTPS session.

I migrated my blog to Hugo two years ago, and never regretted the decision. At the same time I implemented version control with Git, and started using GitHub (and GitLab for a convoluted set of reasons) to host the blog repository.

After hesitating for way too long, I decided to go one step further and made the blog repository public. The next time a blatant error of mine annoys you fork it, fix my blunder(s), and submit a pull request (or write a comment and I’ll fix stuff like I did in the past).

I’m usually telling networking engineers seriously considering whether to automate their networks to cleanup their design and simplify the network services first.

The only reasonable way forward is to simplify your processes – get rid of all corner cases, all special deals that are probably costing you more than you earned on them, all one-off kludges to support badly-designed applications – and once you get that done, you might realize you don’t need a magic platform anymore, because you can run your simpler network using traditional tools.

While seasoned automation practitioners agree with me, a lot of enterprise engineers face a different reality. Straight from a source that wished to remain anonymous…

I stumbled upon a blog post by Diptanshu Singh discussing whether IS-IS flooding in highly meshed fabric is as much of a problem as some people would like to make it. I won’t spoil the fun, read his blog post ;)

The really interesting part (for me) was the topology he built with netlab and containerlab: seven leaf-and-spine fabrics connected with WAN links and superspines for a total of 68 instances of Arista cEOS. I hope he automated building the topology file (I’m a bit sorry we haven’t implemented composite topologies yet); after that all he had to do was to execute netlab up to get a fully-configured lab running IS-IS.

Stuart Charlton did his best to explain the concept of pods in the Kubernetes Networking Deep Dive webinar, but we were still a bit confused. Next step: let’s talk about typical inter-pod traffic scenario.

Continuing the how real is the decade-old SDN hype thread, let’s try to figure out if anyone still uses OpenFlow. OpenFlow was declared dead by the troubadour of the SDN movement in 2016, so it looks like the question is moot. However, nothing ever dies in networking (including hop-by-hop IPv6 extension headers), so here we go.

Why Would One Use OpenFlow?

Ignoring for the moment the embarrassing we solved the global load balancing with per-flow forwarding academic blunders¹, OpenFlow wasn’t the worst tool for programming forwarding exceptions (ACL/PBR) into TCAM.

Even though Gartner declared SDN obsolete before plateau in their 2021 Networking Hype Cycle, most vendor marketers never got the memo. Anything that interacts with network devices in any way¹ is called an SDN controller. Let’s try to throw some minimal amount of taxonomy into that mess based on how these controllers interact with network elements (physical or virtual).

Christoph Jaggi, the author of Ethernet Encryption webinar, published a new version of Ethernet Encryptor Market Overview including:

• Network standards and platforms
• Data plane encryption
• Control plane security
• Key- and system management
• Relevant approvals
• Vendors and products, including detailed feature support matrices.

I started preparing the materials for the SDN – 10 years later webinar, and plan to publish a series of blog posts documenting what I found on various aspects of what could be considered SDN¹. I’m pretty sure I missed quite a few things; your comments are most welcome.

Let’s start with an easy one: software/hardware disaggregation in network devices.

Open-Source Network Operating Systems

I found several widely-used open-source² network operating systems:

Another interesting column by Geoff Huston: performance of TCP congestion control protocols when using Low-Earth Orbit or Geosynchronous Orbit satellites for Internet access.

The last part of the Network Addressing section of How Networks Really Work webinar covered other addressing-related topics starting with address assignment mechanisms.

Here’s another “do these things ever disappear?” question from Enrique Vallejo:

Regarding storage, is Fibre Channel still a thing in 2022, or most people employ SATA over Ethernet and NVMe over fabrics?

TL&DR: Yes. So is COBOL.

To understand why some people still use Fibre Channel, we have to start with an observation made by Howard Marks: “Storage is different.” It’s OK to drop a packet in transit. It’s NOT OK to lose data at rest.

Here’s a short list of major goodies included in netsim-tools release 1.2.2:

• Access VLANs, VLAN trunks and native VLANs implemented on Cisco IOS, Arista EOS, VyOS, and Dell OS10 (VyOS and OS10 support contributed by Stefano Sasso)
• Hardware labs implemented with external topology provider (contributed by Stefano Sasso)
• VRF loopback interfaces (contributed by Stefano Sasso)

More details in the release notes.

Recent news from the Department of Unintended Consequences: RFC 6724 changed the IPv4/IPv6 source/destination address selection rules a decade ago, and it seems that the common interpretation of those rules makes IPv6 Unique Local Addresses (ULA) less preferred than the IPv4 addresses, at least according to the recent Unintended Operational Issues With ULA draft by Nick Buraglio, Chris Cummings and Russ White.

End result: If you use only ULA addresses in your dual-stack network¹, IPv6 won’t be used at all. Even worse, if you use ULA addresses together with global IPv6 addresses (GUA) as a fallback mechanism, there might be hidden gotchas that you won’t discover until you turn off IPv4. Looks like someone did a Truly Great Job, and ULA stands for Useless Local Addresses.