Currently, if you configure a bonded interface you cannot specify any options for the bond -- most importantly "mode" -- but a host of others. A workaround is to modprobe the bonding module with the options you want before loading systemd-networkd, for example: modprobe bonding mode=4 mii=100 lacp_mode=1 systemdctl start systemd-networkd.service Most other configuration file formats for network configuration support specifying bonding options, and it'd be very nice for systemd-networkd to support this as well.
Mode= switch added in http://cgit.freedesktop.org/systemd/systemd/commit/?id=fe8ac65b68. Other options are on the TODO list.
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