Ivan Pepelnjak joins Steinn and Urs to talk about netlab, why multi-vendor ACLs are a hellscape, and what AI can and cannot do with network configuration. Ivan is a CCIE Emeritus, the author of more Cisco Press books than most of us have read, the voice behind ipSpace.net, and the creator of netlab — an open source tool that builds and configures virtual labs across roughly twenty platforms. He describes it himself as an "intent based digital twin lifecycle management system", then immediately admits that's a b******t bingo winner if you have the right card. The conversation digs into why LLMs write decent Python and bad router configs (vendor CLIs are almost identical but not quite, which is the worst possible training data), the ChatGPT doom loop Ivan hit trying to configure EVPN on Nokia SR OS, and the endless device quirks behind multi-vendor abstraction — Juniper loopbacks, Nokia prefix lengths, and one vendor with roughly 400 keywords you are not allowed to use as a VLAN name. Plus: why every layer 3 switch is really a bridge in disguise, why ACLs are containable and QoS never will be, what a real CCIE engagement looks like when you have twenty years of customer mistakes and exactly one command to fix them, and Ivan's controversial opinion on conferences. What we cover What netlab actually is, and the five years behind itWhether netlab is a crutch for beginnersSplitting a lab across multiple servers with automatic VXLAN tunnelsNetlab vs containerlab and Kubernetes-based labsWhy AI generates good Python and bad router configsThe ChatGPT doom loop on Nokia SR OS EVPNCloning production into a lab: control plane works, data plane is a lotteryACL support in netlab, Cartesian products and resequencingAI code review vs AI code — technically correct and five times too longVibe coders, 1982 edition, on a ZX SpectrumLeaky abstractions and worst common denominatorsDevice quirks: Juniper, Nokia, Cisco, and 400 forbidden VLAN names on EXOSWhy every layer 3 switch is a bridge with a router attachedACLs are containable. QoS is not.BGP labs designed like gym machinesWhy CCIE lab scenarios are so insane — and why they're accurateThe power of saying no, and the customer who said thank youControversial opinion: the hallway track is the only trackLinks from the episode netlab: netlab.toolsnetlab on GitHub: github.com/ipspace/netlabnetlab examples: github.com/ipspace/netlab-examplesIvan's blog: blog.ipspace.netFree BGP labs: bgplabs.netFree IS-IS labs: isis.bgplabs.netFree VXLAN/EVPN labs: evpn.bgplabs.netBatfish: github.com/batfish/batfishAerleon: github.com/aerleon/aerleonGuestIvan Pepelnjak — ipspace.net | netlab.tools Hosted by Steinn "Steinzi" Bjarnarson and Urs Baumann. Subscribe and followWatch on YouTube: youtu.be/odcwCByRj6gChannel: youtube.com/@networkautomagicWeb: networkautomagic.net #networkautomation #networkautomagic #netlab #ipspace #AI #networkengineering
