I have Ubuntu 16.04 Server here.
My Ethernet interface is configured to use DHCP via /etc/network/interfaces and also I enabled "allow-hotplug" for the interface. It works. I can boot without cable connected and then plug it in and the interface will be properly configured via DHCP.
Now I want to plug the other end of the cable to another socket of a different network also with DHCP. When I do so I see in dmesg it detects link up/down events but no DHCP discovery requests sent and correspondingly IP address is not changed what basically breaks network access to my device and forces me to manually start dhcp client.
How can I configure my system to rerequest DHCP on cable reconnection?
UPDATE: The easiest solution was to use netplugd. Doing this by native means is too complicated.