I have a scenario where a portable device with Ethernet connectivity
can be plugged it in a variety of 10/100base-T physical access points.
I would like to identify which particular hookup the device is
connected to (_any_ unique identifier), preferrably to the physical
port level, but some kind of a switch or hub id would also be helpful.
Unfortunately I have no control of the access point network
architecture, it could be a number of interconnected managed or
unmanaged hubs or switches.
I would appreciate some education about whether there is an universal
solution, or perhaps a partial one which works for a particular access