ipSpace.net blog

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 FRRout…

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).

I wanted to make my SRv6 lab examples usable with more platforms.

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.

When I implemented prefix filters in netlab (release 1.9.0), I wanted them to match the final device configurations as closely as possible, including the one prefix per entry rule to match the device configuration sequence numbers.

The 5-hour Reliability Theory: Networking through a Systems Analysis Lens webinar by Rachel Traylor is now available without a valid ipSpace.net account.

netlab release 26.09 added support for Syslog clients and servers.

The OSPF is stuck in database exchange state symptom is probably familiar to every networking engineer who ever had to pass a certification exam.

After a long journey, we finally we got to the final scenario in my ITNOG10 Segment Routing workshop: EVPN services over an SR-MPLS core.

netlab release 26.09 brings more network services goodies: The services module supports Syslog clients and servers.

When I started the netlab project, Vagrant was the go-to tool if you wanted to build a virtual environment described in a text configuration file (an idea popularized as infrastructure-as-code).

TL&DR: Badly.

As we discussed in the BGP-Free Core with SR-MPLS blog post, SR-MPLS works as a drop-in replacement for the traditional MPLS control plane.

It goes without saying that if you want to configure (virtual) network devices with any semi-sane configuration mechanism1, the device must have a working IP address.

Every time I wrote something along the lines of NAT is not a security feature, I got the expected pushback from people defending their bad suboptimal design choices.

I can’t even start imagining how much time Vincent Bernat spent creating his interactive introduction to the spanning tree protocol (starting with STP implemented in WebAssembly); the results are simply phenomenal (there’s also a video version for people…

Finding good content in the swamp of AI slop is hard, and whenever I find a blog post worth reading, I’d like to know when the author publishes the next one.

The beauty of SR-MPLS is that it’s a drop-in replacement for the traditional (LDP- or RSVP-based) MPLS control plane.

The vrnetlab project and its containerlab fork implement a wonderful idea: let’s package virtual machines (primarily network devices that cannot be containerized) as containers to use reliable orchestration tools like containerlab to provision network top…

I sure wish Tony Mattke had started publishing his Git-related blog posts in 2017 when I was still struggling with the basics.

I know a few software development companies use netlab to test their network management software (and contribute back to netlab – thanks a million!)

Long, long time ago, in a long-forgotten PR adding support for Cumulus VX Ignite runtime, an off-the-cuff remark was made saying, “and this is how you use netlab with Podman”.

In late June, we added GRE tunnels to netlab, including a Junos implementation.

Summer is almost over, and it’s time to resume regular programming with the next example from the Segment Routing workshop I had at ITNOG10: multi-vendor SR-MPLS.

When someone starts singing the Use Digital Twins to Test Your Network hymn (or, more recently, tells you how AI agents can do that to validate their ideas), ask them about these minor details.

Tony Mattke continues publishing excellent “Git for Networking Engineers” content.

A lot of AI-coding enthusiasts are making claims along the lines of “AI coding tools are like compilers; you supply intent, they translate it into code, and who ever looked at the machine-code output?”

Sakar left an interesting comment on my The Curious Case of the BGP Connect State blog post, claiming that Cisco IOS/XE goes through a CONNECT state when opening an incoming BGP session.

Remember the sage advice to simplify your life and use the IPv6 /64 prefixes everywhere?

Tony Mattke put together a long list of recommendations that might help you get more out of your LLM tokens.

netlab is using the Python Box library to make the code easier to read1.

Last Friday, I had a lovely chat with Steinn Bjarnarson and Urs Baumann, resulting in the NetworkAutoMagic episode 11.

netlab release 26.08 brings a few humongous additions: ArcOS support by @roc-ops VPP (FD.io) with FRR or BIRD control plane by @jbemmel SONiC containers (also by @roc-ops) IPv4/IPv6 access control lists in the routing module by @DanPartelly But wait, ther…

Remember the anonymous troll who chided me for writing a rant instead of opening a GitHub issue in the relevant Ansible repository?

Last December, I wrote a pretty ranty post explaining how Ansible release 12 broke (some?)

Tony Mattke published a blog post I wish I’d read 10 years ago.

The highlights of netlab release 26.07 include: The multiserver plugin by @muddyblack distributes containerlab devices across multiple servers.

Jeroen van Bemmel noticed an interesting fact yesterday evening: the netlab GitHub repository has 2000 merged/closed pull requests.

Just in case you decide to build a simple Python project over the summer: read scripting good practices in Python by Brett Cannon and tell your AI friend to adhere to them ;)

Ali Bahadır Coşkun continued his EVPN/VXLAN journey.

Daniel Blažek couldn’t resist testing Arista EOS centralized anycast gateway functionality (on top of IPv6 underlay to make it even more fun) and published working device configurations in a GitHub repo.

Cisco DevNet channel has published an hour-long Getting Started with netlab interview with Suresh Vina, resulting in netlab.tools documentation having more weekly visits than ipspace.net blog for the first time.

I can confirm that an old saying is true: the older you are, the faster years pass.

The Appearing Productive in The Workplace article I stumbled upon is yet another masterful description of how AI slop, used by Expert Beginners, wastes everyone’s time and energy.

In the previous blog post, I described how ARP works in an EVPN asymmetric IRB environment where the PE devices share an anycast MAC/IP address in addition to a unicast MAC/IP address.

Claudia de Luna published a step-by-step description of how you can use SuzieQ data with an AI agent.

Charity Majors wrote an excellent article describing AI enthusiasts in a race against time and AI skeptics in a race against entropy.

Ali Bahadır Coşkun wrote a nice article describing how he mastered extending a VLAN with static VXLAN with the help of free netlab-powered VXLAN labs.

In previous blog posts, I described the ARP issues in EVPN environments, starting with centralized routing, and then asymmetric IRB with unicast (per-leaf-switch) first-hop gateways.

Chris Grundemann wrote an interesting article arguing that you should structure your network operations around teams, not heroes.