VLANs on the board's switch, with apply-then-confirm

[excavador]

VLANs on the board's switch — shipped in firmware v2.33.0, with three ways to use them

The board's switch has seven ports: four compute modules, the BMC's own port, and the two uplink jacks. Until v2.33.0 they were one flat bridge with no VLAN filtering and no STP, which is why plugging both jacks into the same switch would loop.

This was two pieces of work, and both are in the release.

1. The switch itself. VLAN filtering and STP on the RTL8370MB-CG. The driver is an out-of-tree patch that had no VLAN operations at all; upstream PR turing-machines#257 adds them and was untested there. Landed and proved from the shell first.

2. Configuring it, safely. The switch this configures carries the BMC's own management port, so a wrong VLAN applied through the page you are reading cuts you off from the thing you would fix it with. So the daemon applies the change, starts a window, and reverts unless a confirmation arrives over the new configuration — a confirmation sent from a shell on the board itself crossed no switch port and is refused. Only a confirmed configuration is ever saved, so a reboot during the window comes back on the old one. The window counts from the uplink reaching forwarding, not from the apply, because spanning tree holds a port for its own delay first. Try it in the interface does the apply-and-wait for you and undoes itself.

Three ways to use it, as presets rather than a table of PVIDs — and the table is there too, editable, with every rule checked by the board as you type:

	BMC	modules	needs a VLAN-aware switch upstream
Flat	shared	shared	no — this is the default
Split	one uplink jack	the other jack	no
Trunk	tagged management VLAN	tagged node VLAN	yes

Split is the one most people asked for: one cable for management, one for the cluster, and the separation done on whatever switch you already have. No tag ever leaves the board. @dojo-major described exactly this — hard-link the BMC to one Ethernet port and the nodes to the other, then do real separation upstream.

Trunk is for people who already run VLANs: both on one jack, tagged, with the second jack carrying the same VLANs as a redundant path under STP. VLANs can be named, so the table reads 20 (nodes) rather than a bare number.

What it does, with the measurements: https://turingpi.xyz/news/v2.34.0/ · the guide: https://turingpi.xyz/guides/segment-the-network/ · tpi network switch does all of it from the command line.

Still open from this thread: per-port tagging for the BMC's own port (a tagged sub-interface for the BMC's Linux) — say so below if you need it.

Status: Shipped in v2.33.0