What is a VLAN? 802.1Q tags, access ports and trunks

A VLAN lets one switch act like several. This covers the four-byte 802.1Q tag and its 12-bit VLAN ID, access ports and trunks, how one cable carries every VLAN between two switches, and why a router has to sit between them. Then the native VLAN, the double-tagging attack it allows and how to shut it down, and a real OpenWrt config that puts the IoT gear on its own VLAN. Chapters 0:00 Intro 0:23 One switch, one network 0:48 One switch, two networks 1:14 Four bytes in the frame 1:48 Twelve bits of VLAN 2:15 Access and trunk 2:43 One cable, every VLAN 3:02 The native VLAN 3:22 Two tags, one hop 3:53 Leave VLAN 1 empty 4:12 A router on a trunk 4:43 Fencing off the IoT gear 5:11 When 4,094 isn't enough 5:33 Tag it! Sources Wikipedia — IEEE 802.1Q: https://en.wikipedia.org/wiki/IEEE_80... Wikipedia — VLAN: https://en.wikipedia.org/wiki/VLAN Wikipedia — VLAN hopping: https://en.wikipedia.org/wiki/VLAN_ho... Wireshark Wiki — VLAN: https://wiki.wireshark.org/VLAN Linux kernel docs — Ethernet Bridging: https://docs.kernel.org/networking/br... man7.org — bridge(8): https://man7.org/linux/man-pages/man8... man7.org — ip-link(8): https://man7.org/linux/man-pages/man8... OpenWrt — DSA mini-tutorial: https://openwrt.org/docs/guide-user/n... RFC 7348 — Virtual eXtensible Local Area Network (VXLAN): https://www.rfc-editor.org/rfc/rfc734... Music: Write You by Joey Pecoraro (YouTube Audio Library) Overengineering! · Episode 010