While configuring two vio server the other day, i wanted to transform both vio server SEA cards into SEA failover mode. I fell into the following trap :
If one Vio server is configured as followed :
1 virtual ethernet in vlan / pvid 1 with external network access yes, and trunk pri 1
SEA created between the adapter and this card, and, an internal adress configured on the SEA.
While configuring the other VIO server, in the same way than the first one, in order to transform it in failover mode, later, when you create the SEA adapter (with the virtual adapter on the same Vlan / pvid than the first vio server), you generate a biiig arp storm / broadcast storm, that can put your vlan, and more, down.
So, the good way to do it is to make directly the failover mode, as you create the SEA, or, to transform it before creating the second SEA on the second VIO server.
NOT : mkvdev -sea ent1 -vadapter ent4 -default ent4 -defaultid 3
but directly
mkvdev -sea ent1 -vadapter ent4 -default ent4 -defaultid 3 ha_mode=auto ctl_chan=ent3
Before, you should have the virtual adapter ent3 created, on vlan 3.
OR : if you just need to modify your existing SEA into failover mode :
chdev -dev ent3 -attr ha_mode=auto ctl_chan=ent4
there seems also to be a bypass at the switch level, which could be helpful : its the BPDU guard setting, which disables the port if bridging loop or packet storm occurs.
This is what it looks like at the end (2 differents networks for every partition)
