VLANs across switches: trunks

The idea

alice and a build server on coreSwitch, bob, carol, a desk phone and a printer on floorSwitch: two switches joined by one cable, a trunk. It carries many VLANs, each frame with its tag; one VLAN, the native, goes untagged.

Steps

1. Access ports: the switch does the tagging

   bob is in sales, VLAN 10, on floorSwitch. List floorSwitch's ports (named after their devices) and their VLANs, then bob's card, to find out who does the tagging.

   floorSwitch:~# bridge vlan show
   bob:~# ip -br -4 addr show eth0
   bob:~# ping -c1 -W2 10.0.10.2

2. One trunk, many VLANs

   alice, also in sales, is on coreSwitch, so sales spans two switches and one cable. Read that cable's VLANs, then ping bob from alice while it is recorded.

   floorSwitch:~# bridge vlan show dev coreSwitch
   alice:~# ping -c1 -W2 10.0.10.11