What happened if compute node machine restarts or stop working ??

Hello, I wonder what is happening when a machine that runs computation node with active VMs is shutdown due hardware malfunction or power outage and after some time restarting and returns back? Does OpenStack somehow manage "to move" VMs that were configured to that node to run on another node? What happened to networking between VMs on other nodes trying to reach VMs that were running on the shutdown node?