Cause: When an IP address was re-used it would be generated with a random MAC address that would be different from the previous one.
Consequence: Any node with an ARP cache that still held the old entry for the IP would not be able to communicate with the node.
Fix: Generate the MAC address deterministically from the IP address.
Result: A re-used IP address will always have the same MAC address, so the ARP cache can not be out of sync. So the traffic will flow.