I was running into a bunch of problems with KVM bridging and Ubuntu Bonding (LACP) but I was able to resolve this by using the following network config:
Printout from /etc/network/interfaces
LACP Bonding
# This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # Child Networking interfaces auto eth0 iface eth0 inet manual bond-master bond0 bond-primary eth0 auto eth1 iface eth1 inet manual bond-master bond0 #Bond mode load-balancing LACP fast auto bond0 iface bond0 inet manual bond-mode 4 bond-miimon 1000 bond-lacp-rate 1 bond-slaves eth0 eth1 #Bridged networking interfaces auto br0 iface br0 inet static address 192.168.1.1 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255 gateway 192.168.1.1 # dns-* options are implemented by the resolvconf package, if installed dns-nameservers 8.8.8.8 dns-search nertwork.com bridge_ports bond0 bridge_stp off bridge_fd 0 bridge_maxwait 0