A happy netlab user sent me an unexpected use case: they successfully used its multi-vendor capabilities to argue with a vendor TAC. Here’s the gist of the story (edited/anonymized for obvious reasons):

A month ago, I described ARP issues in EVPN centralized routing design, and Naveen Kumar Devaraj was kind enough to add some Arista EOS implementation details. Today, let’s explore what EVPN routes Arista EOS generates in that scenario. We’ll use a very simple lab topology with a spine switch acting as a router. The leaf switches are layer-2 switches.

Tony Mattke built several networking-focused CLI tools and released them on GitHub. You might find them useful.

After the simple SR-MPLS demo and the dual-stack SR-MPLS setup, it was time for the next obvious question: Does SR-MPLS work over unnumbered IPv4 interfaces¹, assuming the implementation of the underlying routing protocol supports them? Of course it does; let’s go through the details, using the same topology I used throughout the Segment Routing workshop @ ITNOG10.

Here’s a short glimpse into the history of telecommunications: in a building at the top of this mountain (barely noticeable blip across the saddle from the radio tower; search for Capo Figari for more details), Guglielmo Marconi conducted experiments in the ~1930s (after inventing the wireless telegraph system in the late 1890s).

The original radio could “transmit” at most 40-60 words per minute (the limit of a skilled Morse Code operator). 130 years later, I’m writing this blog post using a 200 Mbps Internet connection via a low-earth-orbit satellite with response times low enough that I can run an interactive SSH session with no noticeable delay. It’s almost incomprehensible how far we’ve come in such a short time.

Doug Madory wrote an interesting article (published on APNIC blog) arguing that we shouldn’t worry about ephemeral BGP leaks that can be observed only during the BGP path hunting process that follows a route withdrawal.

I have to disagree with that. It’s never a good idea to ignore a dead canary in the coal mine.

While the ephemeral leaks do not impact the end result (after all, the route is gone), they are an important indicator of the lack of BGP route policy enforcement in the autonomous systems that propagate them. If an autonomous system is propagating a bogus route when no better routes are available, it’s equally likely to propagate a bogus route when an intruder manages to inject it.

After fixing the SR Linux LDP configuration template, I decided to add MPLS/VPN to the netlab SR Linux MPLS features. After all, the one-page recipe seemed simple enough, more so as we already have tested VRF and EVPN templates.

Alas, nothing is as simple as it looks. There were two details that tripped me pretty badly.

Did you manage not to stumble on a dramatic post explaining how someone generated 10,000 lines of code with AI while wasting time on your LinkedIn feed? Congratulations, you’re lucky.

However, as Nathaniel Fishel explained in his Your Code Is Worthless article, the “lines of code” is a useless vanity metric that sounds great in a LinkedIn self-promotion, but doesn’t matter when one has to maintain the product one has shipped to the customers. Add the natural laziness, and you have a perfect storm. As he wrote:

Remember OpenFlow, the One Protocol to Bind Them All¹? I haven’t heard anyone even mention it in ages, and I never bothered to ask whether anyone is still using it after the dismal results of the 2022 poll.

Anyway, if you still have to deal with that ancient blunder, six hours of deep dive videos I recorded a decade ago might still be useful. You can watch them without an ipSpace.net account.

Looking for more binge-watching materials? You’ll find them here.

After the introduction to SR-MPLS demo I did during the Segment Routing workshop @ ITNOG10, we moved to dual-stack SR-MPLS – can we assign node segment identifiers (SIDs) to IPv4 and IPv6 prefixes? The demo used the same three-router network as the previous one, with IPv4 SIDs starting at one and IPv6 SIDs starting at 101: