Erros com interfaces em ponte

Question

Eu tenho problema com o Debian rodando como um VirtualBox Guest. Eu posso configurar uma ponte, mas inundar os logs com muitos erros e o sistema se torna inutilizável. Erros como:

Nov 12 16:30:55 jessie-gnome kernel: [ 737.277528] br0: received packet on eth0 with own address as source address

Nov 12 16:31:00 jessie-gnome kernel: [ 742.280085] net_ratelimit: 47185 callbacks suppressed

Nov 12 16:31:00 jessie-gnome kernel: [ 742.280088] br0: received packet on eth1 with own address as source address

Nov 12 16:31:00 jessie-gnome kernel: [ 742.280178] br0: received packet on eth1 with own address as source address

Nov 12 16:31:00 jessie-gnome kernel: [ 742.280282] br0: received packet on eth1 with own address as source address

Meus arquivos de interfaces possuem:

auto lo
iface lo inet loopback



iface eth0 inet manual

iface eth1 inet manual

auto br0
iface br0 inet static
    address 192.168.80.5
    netmask 255.255.255.0
    network 192.168.80.0
    gateway 192.168.80.1
     bridge_stp off       # disable Spanning Tree Protocol
     bridge_fd 0          # no forwarding delay
     bridge_ports eth0 eth1
     up iptables -I FORWARD -m physdev --physdev-is-bridged -j ACCEPT

E esses são os processos que consomem mais tempo da CPU:

  580 avahi     20   0   32224   2756   2492 R 16,2  0,2   1:30.48 avahi-daemon                                                                     
    3 root      20   0       0      0      0 R 15,5  0,0   1:43.27 ksoftirqd/0                                                                      
  923 root      20   0  215988  34140  18968 S 15,2  2,2   0:34.59 Xorg                                                                             
 1261 sergio    20   0 1330672 202952  68820 R 12,9 13,2   0:32.71 gnome-shell                                                                      
    7 root      20   0       0      0      0 S 12,6  0,0   1:22.70 rcu_sched  

OS é o Debian 8.

Como posso corrigir esses erros?