It depends on how the last mile access is configured.
Sometimes layer 2 end segments are shared (like doccis) it would break those 2 devices on doccis.
I don't believe the gpon standard has the same problem.
It would cause a problem on wireless based access or on embedded ISPs in buildings, they usually shortcut and just put a /24 and push users are onto the same vlan.
Again it only breaks those 2 devices, unless the network sees mac-moves and blocks a port.
It depends on how the last mile access is configured.
Sometimes layer 2 end segments are shared (like doccis) it would break those 2 devices on doccis.
I don't believe the gpon standard has the same problem.
It would cause a problem on wireless based access or on embedded ISPs in buildings, they usually shortcut and just put a /24 and push users are onto the same vlan.
Again it only breaks those 2 devices, unless the network sees mac-moves and blocks a port.