When doing multinode, we connect the br-ctlplane bridges with VXLAN
tunnels, so the bridge has an MTU of 1400 (since the interface has
1500 in most infras).
However when creating Neutron tenant networks that will use overlay, on
top of these bridges, we need to lower the default MTU (1500) to work
in this setup, so using 1300 should be safe, since the tunnels are
1400.
When doing multinode, we connect the br-ctlplane bridges with VXLAN tunnels, so the bridge has an MTU of 1400 (since the interface has 1500 in most infras).
However when creating Neutron tenant networks that will use overlay, on top of these bridges, we need to lower the default MTU (1500) to work in this setup, so using 1300 should be safe, since the tunnels are 1400.