I have a Rasbperry Pi running Raspbian 8 (Jessie). The Wifi adapter and the Ethernet adapter are bridged (br0), and the bridge is assigned a static IP address. (See my solution in this post for details on the configuration.)
The bridge works fine as long as the Ethernet connection is "live" - i.e. is plugged into either a switch or another active system via a crossover cable. However, if the Ethernet link goes down (i.e. the cable is unplugged or the switch or the remote system is powered off) the bridge stops responding.
The bridge's IP is the IP for the system. If it stops responding, the device (and all the services running on it) becomes unavailable over Wifi. Not good.
Is there a way to configure the bridge so that it continues to respond / operate as expected regardless of the link state of the Ethernet interface?
Here's the configuration:
auto eth0 iface
eth0 inet manual
auto wlan0 iface
wlan0 inet manual
auto br0 iface
br0 inet static
bridge_ports eth0
address 10.26.36.1
netmask 255.255.255.0
network 10.26.36.0
broadcast 10.26.36.255
post-up /usr/sbin/stratux-wifi.sh
Notice that the eth0 interface is added to the bridge configuration in /etc/network/interfaces while the wlan0 interface is added later by the start of the hostapd daemon (run by the post-up script).
For whatever it's worth: I've tried booting the system up with the Ethernet connection unplugged and while the boot takes a bit longer (the configuration of the Eth0 port has to timeout) it does work.
ip link eth0 set nomaster, orbrctl) after the interface goes down? Do your RaspPi's use the traditional ifup/ifdown and get events ifeth0goes down?