On Mon, 2014-10-06 at 12:51 -0700, Ed Swierk wrote: > I'm using NetworkManager on a server with two wired Ethernet interfaces > (eth0 and eth1) configured as slaves of a bond in active-backup mode. I'd > like the bond interface to always be assigned eth0's MAC address. > > This is easy with old-school static network configuration like ifupdown: > just make eth0 the first slave of the bond interface, and Linux will copy > eth0's MAC address to the bond. > > When NetworkManager starts up and reads system-interface config files, it > creates the bond interface right away, but doesn't add a slave until it > notices that the slave's link is up (i.e. carrier is 1). And of course the > link state depends on lots of things, like whether a cable is plugged in > and the state of the switch or host at the other end. Thus whether eth0 or > eth1 gets enslaved to the bond first is unpredictable, meaning the bond > interface's MAC address is unpredictable. This is troublesome in some > environments, such as ones where a DHCP server assigns IP addresses based > on the MAC address of the client.
Does setting the "primary" bond option when in active-backup mode to "eth0" make things better? In nm-connection-editor it'll be in the page for Bond options, in nmtui it'll be in about the same place, and in nmcli you'd do: nmcli con mod Bond1 +bond.options "primary=eth0" and then re-activate the connection. Let me know if that does/doesn't help. (note; this may only work with 0.9.10+) Dan > NetworkManager already treats a bond slave interface differently when its > link goes down, leaving it in DISCONNECTED state rather than switching it > to UNAVAILABLE. So there's precedent for having a bond interface with one > or more link-down slave interfaces. I think the easiest way to achieve a > stable MAC address is to extend that behavior to the startup case: as soon > as NetworkManager sees an interface that's configured as a bond slave, it > should move it from UNAVAILABLE to DISCONNECTED. That way the first > configured slave interface, rather than the first one with link up, is > enslaved to the bond. > > I couldn't figure out a way to configure this in NetworkManager 0.9.8.10, > nor in mainline code. As a proof of concept, I hacked > nm_device_state_changed() in src/nm-device.c: in the second switch(state), > UNAVAILABLE case, I force the transition to DISCONNECTED for eth0 and eth1. > This works as I'd hoped: both interfaces are enslaved right away, with eth0 > always first. > > I didn't see any easy way to implement this behavior cleanly, though. This > new behavior should apply only to bond slave interfaces. At the point where > nm_device_state_changed() is called, there's not yet a corresponding > connection for eth0 or eth1, so I can't check whether the interface is > configured as a bond slave. I thought I'd ask for advice before spending > more time on this. > > Any help would be appreciated! > > --Ed > _______________________________________________ > networkmanager-list mailing list > networkmanager-list@gnome.org > https://mail.gnome.org/mailman/listinfo/networkmanager-list _______________________________________________ networkmanager-list mailing list networkmanager-list@gnome.org https://mail.gnome.org/mailman/listinfo/networkmanager-list
