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

auto bond0

iface bond0 inet static


netmask gateway

slaves none

bond-mode 802.3ad

bond-miimon 100

bond-downdelay 200

bond-updelay 200

bond-lacp-rate 1

auto eno1

iface eno1 inet dhcp

auto eno2

iface eno2 inet manual

auto eno3

iface eno3 inet manual

bond-master bond0

auto eno4

iface eno4 inet manual

bond-master bond0

auto br0

iface br0 inet manual

bridge_ports eno2

bridge_fd 9

bridge_hello 2

bridge_maxage 12

bridge_stp on

Here is the cisco interface config,log output and tcpdump results.

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