Comment 3 for bug 1634269

This is a means to re-use the port (and its allocated address and MAC) without deleting the port and creating a new one with the same address and MAC. Obviously, you can't create a port before deletion with the same address and MAC, but you also can't create the port reliably after deletion because you can lose either address to another port - it's a race condition.

In the original test case, the issue was a host going down cauing a VM failure. The VM doesn't delete promptly on a freshly downed host (and deleting a VM takes an uncertain amount of time in any case), so it's impossible to free the port by conventional means, and replacing the VM requires recycling its address.