Ethernet-Wifi failover on FreeBSD

I want a simple behaviour with my laptop:

1. If Ethernet cable connected use this connectivity, otherwise use the wireless;
2. I want to kept the same IP addresses, event if I'm using DHCP client.

The solution is quiet simple:

1. set-up an aggregate interface in failover mode with Ethernet as primary and wireless as backup;
2. Clone the Wireless MAC NIC to the Ethernet (opposite is not always possible with wireless chipset restriction).

Here are how to do it:

# ifconfig -l
iwn0 bge0 lo0
=> My Ethernet NIC is "bge0" and wireless is "iwn0" here

# set MAC=`ifconfig wlan0 | grep ether | cut -d ' ' -f 2`
# sysrc ifconfig_bge0="ether $MAC"
ifconfig_bge0:  -> ether 00:1c:23:25:ab:45
# sysrc wlans_iwn0=wlan0
wlans_iwn0:  -> wlan0
# sysrc ifconfig_wlan0="WPA up"
ifconfig_wlan0: WPA DHCP -> WPA up
# sysrc cloned_interfaces=lagg0
cloned_interfaces:  -> lagg0
# sysrc ifconfig_lagg0="laggproto failover laggport bge0 laggport wlan0 DHCP"
ifconfig_lagg0:  -> laggproto failover laggport bge0 laggport wlan0 DHCP
# sysrc ifconfig_lagg0_ipv6="inet6 accept_rtadv"
ifconfig_lagg0_ipv6:  -> inet6 accept_rtadv
# service netif restart

And now with Ethernet cable unplugged:

# ifconfig lagg0
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
    ether 00:1c:23:25:ab:45
    inet6 fe80::41d:23ff:fe25:ab78%lagg0 prefixlen 64 scopeid 0x4
    inet6 2a01:e35:9b9d:a1a0:41d:23ff:fe25:ab45 prefixlen 64 autoconf
    inet 192.168.100.7 netmask 0xffffff00 broadcast 192.168.100.255
    nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
    media: Ethernet autoselect
    status: active
    laggproto failover lagghash l2,l3,l4
    laggport: wlan0 flags=4<ACTIVE>
    laggport: bge0 flags=1<MASTER>


Then If I plug the Ethernet cable:


# ifconfig lagg0
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
    ether 00:1c:23:25:ab:45
    inet6 fe80::41d:23ff:fe25:ab45%lagg0 prefixlen 64 scopeid 0x4
    inet6 2a01:e35:9b9d:a1a0:41d:23ff:fe25:ab45 prefixlen 64 autoconf
    inet 192.168.100.7 netmask 0xffffff00 broadcast 192.168.100.255
    nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
    media: Ethernet autoselect
    status: active
    laggproto failover lagghash l2,l3,l4
    laggport: wlan0 flags=0<>
    laggport: bge0 flags=5<MASTER,ACTIVE>