Network protocols, explained by the people who parse them

NacTrack reads the configuration and state of these protocols on production networks every day. This series explains what we read there: how each protocol works, what each vendor does by default, and where real networks get it wrong.

Each episode is a video, and its page carries the full text. The commands are the vendors' own, checked against their documentation, and the screens come from an entirely fictional demonstration network.

The series starts with switching, spanning tree then VLANs and trunks, moves to routing with OSPF and BGP, to monitoring and neighbour discovery with SNMP then LLDP and CDP, and reaches the data centre fabric with VXLAN and EVPN. From there it grows, one episode at a time, to the other protocols NacTrack reads.

Each page sets out the principle of the protocol, the commands that read it on the four vendors, their defaults where they differ, and the failures that actually happen in production.