Today, I'm sharing another piece of my experience from the NANOG88 conference where I had the privilege of presenting a tutorial featuring pyGNMI, a powerful tool for diagnosing network issues. During my talk, I used pyGNMI to visualize EVPN Layer2 and Layer 3 domains, sorting them by switch or network instance. I also added a special feature that detects discrepancies in the settings between different switches using the same EVPN domain – a great way to catch typos in your BGP/VXLAN settings.
The script demonstrates how to use pyGNMI to retrieve BGP EVPN information from a list of routers. It then formats the data for easy viewing.
For real world use cases, you would likely wrap pyGNMI with Nornir and leverage Nornir's inventory and task management capabilities, like shown here.
For this demonstration, I leveraged containerlab and Nokia SR Linux to build a VXLAN-EVPN Fabric, replicating a typical configuration I often use in my Kubernetes labs. I incorporated eBGP for underlay communication, and the topology I utilized comprised two spines, two leaf switches, and a border leaf.
In this blog post we are going to dive into the details of the script, discovering how it works and what it is capable of. If you want to try it out yourself, you can find the source code in the pygnmi-srl-nanog88 repo