I have encountered a problem with configuring vlan tagged linux bridges, on a Cisco small businesses switches trunk interfaces. Our environment consists of 3 servers and one switch, that handles lacp and vlan distribution. Our problem is that when we try to configure a tagged bridge, it immediately enables loopback detection and interface goes offline. Tcpdump and kernel logs show that nothing terrible is going on. The problem seems to be highly reproducible for our environment. Any assistance in helping solving this case would be very appreciated)
The following networking config is the same for all our servers.
auto lo iface lo inet loopback
iface bond0 inet static
netmask 255.255.255.0 gateway 192.168.1.1
iface eno1 inet dhcp
iface eno2 inet manual
iface eno3 inet manual
iface eno4 inet manual
iface br0 inet manual
Here is the cisco interface config,log output and tcpdump results.