In December 2020, I got sick-and-tired of handcrafting Vagrantfiles and decided to write a tool that would, given a target networking lab topology in a text file, produce the corresponding Vagrantfile for my favorite environment (libvirt on Ubuntu). Nine months later, that idea turned into a pretty comprehensive tool targeting networking engineers who like to work with CLI and text-based configuration files. If you happen to be of the GUI/mouse persuasion, please stop reading; this tool is not for you.

During those nine months, I slowly addressed most of the challenges I always had creating networking labs. Here’s how I would typically approach testing a novel technology or software feature:

When I started collecting topics for the September 2021 ipSpace.net Design Clinic one of the subscribers sent me an interesting challenge: are there any open-source alternatives to Cisco’s DMVPN?

I had no idea and posted the question on Twitter, resulting in numerous responses pointing to a half-dozen alternatives. Thanks a million to @MarcelWiget, @FlorianHeigl1, @PacketGeekNet, @DubbelDelta, @Tomm3h, @Joy, @RoganDawes, @Yassers_za, @MeNotYouSharp, @Arko95, @DavidThurm, Brian Faulkner, and several others who chimed in with additional information.

Here’s what I learned:

Non-Stop Forwarding (NSF) is one of those ideas that look great in a slide deck and marketing collaterals, but might turn into a giant can of worms once you try to implement them properly (see also: stackable switches or VMware Fault Tolerance).

One of my subscribers is trying to decide whether to buy an -EX or an -FX version of a Cisco Nexus data center switch:

I was comparing Cisco Nexus 93180YC-FX and Nexus 93180YC-EX. They have the same port distribution (48x 10/25G + 6x40/100G), 3.6 Tbps switching capacity, but the -FX version has just 1200 Mpps forwarding rate while EX version goes up to 2600 Mpps. What could be the reason for the difference in forwarding performance?

Both switches are single-ASIC switches. They have the same total switching bandwidth, thus it must take longer for the FX switch to forward a packet, resulting in reduced packet-per-seconds figure. It looks like the ASIC in the -FX switch is configured in more complex way: more functionality results in more complexity which results in either reduced performance or higher cost.

A friend of mine pointed out this quote by John Shoch when I started preparing the Network Stack Addressing slide deck for my How Networks Really Work webinar:

The name of a resource indicates what we seek, an address indicates where it is, and a route tells us how to get there.

You might wonder when that document was written… it’s from January 1978. They got it absolutely right 42 years ago, and we completely messed it up in the meantime with the crazy ideas of making IP addresses resource identifiers.

Noël Boulene decided to automate provisioning of NSX-T distributed firewall rules as part of his Building Network Automation Solutions hands-on work.

What makes his solution even more interesting is the choice of automation tool: instead of using the universal automation hammer (aka Ansible) he used Terraform, a much better choice if you want to automate service provisioning, and you happen to be using vendors that invested time into writing Terraform provisioners.

One of the major challenges of using netsim-tools (now renamed to netlab) was the installation process – pull the code from GitHub, install the prerequisites, set up search paths… I knew how to fix it (turn the whole thing into a Python package) but I was always too busy to open that enormous can of worms.

That omission got fixed; netlab is now available on PyPI and installed with pip3 install networklab.

As early as 1994 (on April 1st, to be precise) a satire disguised as an Informational RFC was published describing the deployment of IPv9 in a parallel universe.

Any similarity with a protocol that started as a second-system academic idea and is still experiencing hiccups in real world even though it could order its own beer in US is purely coincidental.

Justin Pietsch wrote another fantastic blog post, this time describing how they simplified Amazon’s internal network, got rid of large-scale VLANs and multi-NIC hosts, moved load balancing functionality into a proxy layer managed by application teams, and finally introduced merchant silicon routers.

After almost a decade of bickering and haggling (trust me, I got my scars to prove how the consensus building works), the authors of Operational Security Considerations for IPv6 Networks (many of them dear old friends I haven’t seen for way too long) finally managed to turn a brilliant document into an Informational RFC.

Regardless of whether you already implemented IPv6 in your network or believe it will never be production-ready (alongside other crazy stuff like vaccines) I’d consider this RFC a mandatory reading.

Two interesting container images were released in June/July 2021:

• Michael Kashin managed to package Cumulus VX into a container image (more details).
• Roman Dodin managed to persuade Nokia to release SR Linux as a container.

Both images can be downloaded with no strings attached (two major wins for the good guys) and are supported with the latest release of netsim-tools:

I thought I was too harsh every now and then, but I’m a complete amateur when compared to Minh Ha’s take on OpenFlow.

Indeed Quantum Computing and OpenFlow have a lot in common. They both create stories that have emotional appeal, they both require invention of new physics, and they’re both filled with grand vision, grandstanding, and empty promises. But there’s no shortage of PhDs, high hopes, cash infusion from VCs, and a Cambrian explosion of research papers, many of which content is not even worth the papers it’s printed on.

I read an excellent rant by prof. Victor Galitski describing the current explosion of Quantum Computing hype, and couldn’t help being reminded of the OpenFlow brouhaha we experienced almost a decade ago – you could do a simple search-and-replace and the article would have been equally valid.

Enjoy… and remember the details for the next time your beloved vendor comes along with Quantum Computing slide deck.

I planned to take my summer break seriously and stop blogging until late August, but then I shouldn’t have looked at my Twitter feed (my bad), where the AI algorithms selected just the right morsel to trigger the maximum rantiness. I would strongly recommend you read the original tweet and all the responses first – it looks like it was a serious suggestion, not a trolling exercise (here’s a copy of the original idea in case the tweets get lost in the mists of time).

In February 2018, Irena Marčetič joined ipSpace.net to fix the (lack of) marketing. After getting that done, she quickly took over most of sales, support, logistics, content production, guest speaker coordination… If you needed anything from us in the last few years, it was probably Irena answering your requests and helping you out.

She did a fantastic job and transformed ipSpace.net from Ivan and an occasional guest speaker to a finely tuned machine producing several hours of new content every month. She organized our courses, worked with guest speakers, podcast guests and hosts, participated in every guest speaker webinar to take notes for the editing process, managed content editing, watched every single video we created before it was published to make sure the audio was of acceptable quality and all the bloopers were removed… while answering crazy emails like I need you to fill in this Excel spreadsheet with your company data because I cannot copy-paste that information from your web site myself and solving whatever challenges our customers faced.

Unfortunately, Irena decided to go back to pure marketing and is leaving ipSpace.net today. Thanks a million for all the great work – we’ll badly miss you.