My ISP uses PPPoE on their DSL connections.
I use Network Manager to connect to this using a bridged modem connected to eth0.
Often, I want to test networking things, so a set myself up a KVM machine with a tap interface. I can then connect these interfaces to to virtual 'switches' by adding them to bridges.
(I work for my ISP). Sometimes, I want to test cases where the PPPoE is connected more than once. For this, I would like to be able to add eth0 to my 'switch' (a bridge) so the VMs can have a 'bridged modem' connection to the internet.
But I would like to still be able to run the PPPoE for my computer at the same time. Which means that I need to get network-manager to run PPPoE over the bridge (or eth0). The problem is that it considers eth0 (and the bridge) 'not managed' by network manager, so it refuses to use it.
So, how can I have network manager dial PPPoE over a bridge?