When a bond in balance-slb is created, the ports are enabled or disabled
based on carrier and link state. If the link/carrier goes down, the port
becomes disabled and we must make sure the MAC tables of the switches
are updated properly so the traffic is redirected.
In order to solve this, we send a GARP or RARP broadcast packet on the
bond. This fix cover 3 different balance-slb scenarios.
Scenario 1: The bond in balance-slb mode has IPv4 address configured and
some ports connected. Here the bond is acting like active-backup as the
packets will always have as source MAC the address of the bond
interface. When a port goes down, NetworkManager will send a GARP
broadcast announcing the address configured on the bond with the MAC
address configured on the port.
Scenario 2: The bond in balance-slb mode is connected to a bridge and has
some ports connected. The bridge has IPv4 configured. When a port goes
down, NetworkManager will send a GARP broadcast announcing the address
configured on the bridge with the MAC address configured on the port.
Scenario 3: The bond in balance-slb mode is connected to a bridge and
has some ports connected. The bridge does not have IP configuration and
therefore everything is L2. When a port goes down, NetworkManager will
query the FDB table and filter the entries by the ones belonging to the
bridge and the bond ifindexes. Then, it will send a RARP broadcast
announcing every learned MAC address from FDB.
Fixes: e9268e3924 ('firewall: add mlag firewall utils for multi chassis link aggregation (MLAG) for bonding-slb')
