On Wed, Mar 15, 2017 at 04:24:02PM +0100, Viktor S. Wold Eide wrote:
On Wed, Mar 15, 2017 at 3:16 PM, Beniamino Galvani <bgalvani redhat com> wrote:You can achieve this by creating two connections with different autoconnect priorities: nmcli connection add type ethernet ifname eth0 con-name eth0-auto nmcli connection add type ethernet ifname eth0 con-name eth0-ll nmcli connection modify eth0-auto connection.autoconnect-priority 100 nmcli connection modify eth0-ll connection.autoconnect-priority 50 ipv4.method link-local In this way NM will try first to autoactivate eth0-auto and, upon failure, it will fall back to the link-local connection.Hi Beniamino, Thanks a lot for the quick response and for the suggestion. What would happen if the DHCP server is only temporary down in the scenario with two connections that you describe? I would expect that the low priority link-local would remain active, even if the DHCP server came back up.
Correct, the link-local connection remains active until someone manually reactivates the DHCP connection, or the system is rebooted.
If there are other alternatives, I would appreciate suggestions.
I'm not aware of alternatives at the moment.
As written, a different DHCP client could have been an option, but no luck so far in this direction.
AFAIK dhcpcd support in NetworkManager hasn't received updates since long time and I don't know if it is still working well, but you should be able to turn it on. You said that dhcpcd supported the fallback to link-local addresses, but I don't see code in NM to do that. Maybe this logic was done entirely in the client, but I wonder if this works when dhcpcd is controlled by NM.
Alternatively, it might be possible to hook into the system, for example via a script in /etc/NetworkManager/dispatcher.d that can check for DHCP failure / success. However, I was wondering if I had missed something or whether there is some recommended configuration to achieve the desired behavior.
We have an open bugzilla [1] about supporting multiple IP methods (DHCP, link-local, static) at the same type for a connection. Probably that enhancement would solve your case, but at the moment I don't think anybody is working on it. Beniamino [1] https://bugzilla.gnome.org/show_bug.cgi?id=773481
Attachment:
signature.asc
Description: PGP signature