Blog Posts in June 2026
netlab 26.06: OSPFv3 on FortiOS, MPLS/VPN on SR Linux
netlab release 26.06 adds OSPFv3 support on FortiOS (by @a-v-popov) and MPLS/VPN support on SR Linux. We also ensured the installation scripts work on Ubuntu 26.04 (everything else was OK) and updated the installed Vagrant version to 2.4.9 (we’re not using new Vagrant features; you don’t have to upgrade it in an existing installation).
Other than that, we added a few improvements and squashed a number of bugs.
Upgrading or Starting from Scratch?
- To upgrade your netlab installation, execute
pip3 install --upgrade networklab. - New to netlab? Start with the Getting Started document and the installation guide.
- Need help? Open a discussion or an issue in netlab GitHub repository.
Lab: Implementing VRF-Lite with VXLAN
Did you know that you can implement a VRF-Lite design with VXLAN? All you need are devices that can run VRF routing protocols over VXLAN-backed VLAN segments.
Compared to the “traditional” VRF-Lite design, in which you need a set of VLANs on every link and every device running the routing protocol for every VRF, the VXLAN-based design needs just IP routing on the core switches, resulting in a design that’s pretty close to what we were building with DMVPN (without IPsec and NHRP complications).
Using netlab to Argue with Vendor TAC
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):
EVPN Centralized Routing with Arista EOS
TL&DR: SIP of Networking Was an Understatement 🤦♂️
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.
Packet forwarding in centralized routing design
Worth Reading: Building the Tools I Wished I Had
Tony Mattke built several networking-focused CLI tools and released them on GitHub. You might find them useful.
SR-MPLS over Unnumbered Interfaces
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.
