Once upon a time, Aoife Moloney amoloney@redhat.com said:
Enable IPv4 Address Conflict Detection by default in NetworkManager.
Huh, I didn't realize NM didn't already do this... ye olde network-scripts did.
To the rescue comes [https://www.rfc-editor.org/rfc/rfc5227 RFC 5227] (“IPv4 Address Conflict Detection”) which provides a mechanism to detect address conflicts. A host implementing Address Conflict Detection (from now on “ACD”) sends ARP probes for each IP address it wants to use; if another host replies, the address is already in use and can’t be configured on the interface.
How does NM handle a duplicate address if there are multiple addresses configured on the interface? Does it continue with the non-dupe addresses or deconfigure the whole interface?
When there are multiple addresses configured, does NM run DAD in series or parallel?
This change aims at enabling ACD by default in Fedora 40, by setting the default value to 3000ms.
3 seconds seems kind of high (IIRC network-scripts used 1 second).