Clicking a heading sorted the table but nothing said so afterwards - the
only feedback was the rows moving, which is no help when the sort key is a
column you are not looking at.
Give every sortable heading a permanent marker: a neutral double arrow when
it is not the sort key, up or down when it is. The marker sits in its own
span so the i18n pass, which replaces the heading text, does not wipe it.
The port column was mapped from logical to physical numbering first and the
CPU label applied afterwards, testing for port 9. On an 8+1 board the SFP
port maps to physical 9 as well, so every entry learned on the SFP was shown
as CPU - on this switch that was 26 of 30 entries.
Label the CPU while the number is still logical, before the mapping, so the
two cannot collide.