How disruptive are switch config changes? If I edit /etc/network/interfaces to add a new port, vlan, etc - does a `systemctl restart networking` (or whatever equivalent) bounce ports or halt switching for a moment while changes are applied?
They are seamless as long as your configuration does not do something stupid like tear down interfaces to reconfigure them. The switch takes no noticeable time to program from the Linux space to the ASIC
> - does a `systemctl restart networking` (or whatever equivalent) bounce ports or halt switching for a moment while changes are applied?
"systemctl restart networking" will typically blow away even the well most well configured systems in my experience.
In the post I suggest using ifupdown (the first one), since it's the most "easy" to debug, but I'm sure networkctl works too, with a healthy amount of systemd restraint
IIRC the /etc/network/interfaces does a reconfiguration that's pretty disruptive.
Things like brctl and ethtool worked on the fly without issues (note though that I mostly used Arista years ago).
It is usually non-disruptive if it gets applied as deltas. If your config tool does a teardown/recreate then that's disruptive. Within the bounds of ethernet and routing protocols (OSPF DR/DBR changes are disruptive, STP can be fun, ....).