On Sat, 7 Apr 2018 09:59:37 +0200 "Marc Roos" <M.Roos@xxxxxxxxxxxxxxxxx> wrote: > In this situation I can ping a vm from br0 connected to 172.16.1.y > > > > +-----------+ > | BR0 | > 172.16.1.y | | 172.16.1.x > --------|ETH2 TUN1|------- > | | > | | 172.16.1.x > | TUN2|------- > | | > +-----------+ > > When only adding a 2nd eth adapter with 'brctl addif br0 eth1' connected > to 10.11.12.y. The same ping is not working anymore. > > > +-----------+ > | BR0 | > 172.16.1.y | | 172.16.1.x > --------|ETH2 TUN1|------- > | | > | | 172.16.1.x > 10.11.12.y | TUN2|------- > --------|ETH1 | > +-----------+ > > When I remove the eth1 again, the ping starts working again. > > Can someone explain me why the bridge is behaving like this? And how > this can be fixed? > > > > Are you creating a spanning tree loop? Also. Bridge is a Layer 2 device not a Layer 3 device; therefore generally all interfaces in a bridge have same subnet.