Prior "bridge: Change local fdb entries whenever mac address of bridge device changes" [1],
FDB entry for a bridge was not inserted when creating the bridge and it could
only be inserted when a hw address of the bridge was changed. Therefore, on
an older than the 3.14 kernel containers were not able to reach
the "weave" bridge w/o setting the promiscuous mode on.
This should have hit hard Kubernetes users as the weave bridge in their
case is used as a default gateway, and thus it works only after manually
enabling the promiscuous mode.
Additionally, w/o the promiscuous mode a packet sent from a container and
destined to the gateway is flooded on all ports, so it can reach
the "datapath" device resulting in the "Vetoed installation of hairpin flow" error.
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a4b816d8ba1c1917842dc3de97cbf8ef116e043e
Martynas Pumputis