The switch learns the MAC addresses observed from frames received through each port and uses this information to forward incoming frames only to the intended destination instead of flooding the network. Different ports of the switch can be connected to different network segments or individual nodes. If the switch did MAC address translation like that, then the control software could determine which port the device was connected to simply by looking at the last section of the fake MAC address.An Ethernet switch connects a number of Ethernet stations, forming an Ethernet network. so that any device that is plugged in to port #n always appears (to the Linux computer) as if it has MAC address foo:bar:baz:n, and therefore shows up as IPv6 address fe80::2foo:bar:baz:n. But assuming that's the case, the next best thing would be if I could program the switch to do MAC address translations, e.g. I don't think that it's possible for the Linux computer to tell which switch port a particular device is connected to (let me know if I'm wrong about that). That way the tester can just follow the ethernet cable to faulty device, rather than having to figure out what each device's MAC address is until he/she finds the matching one. One option is for the error log/message to include the device's MAC address (derived from its link-local IPv6 address), and that might be sufficient in a pinch, but it would be much nicer if the testing program could also say something like 'The device connected to port #5 isn't working right, have a look at that one'. The issue at hand how to indicate to the testing person when a particular device has failed a test.

There will typically be a dozen or so of these devices connected at once (so we can run tests in parallel), and devices will be connected and disconnected on a regular basis by people who don't necessarily know anything about networking they only know how to plug in an Ethernet cable, then (some hours later) look at the PC's screen to see if the test passed or not. I've got a testing scenario where some (GUI-less/embedded) IPv6 devices are going to be temporarily plugged into the ports of a managed Ethernet switch, and a control program (running on a separate Linux PC, also connected to the switch) will detect when one of these devices appears on the LAN, and automatically run a test to make sure the device is working correctly. Just a shot in the dark here, but I thought I'd ask in case anyone has some ideas:

Mac ethernet switch