Description of problem:

When using Linux Bridge plugin, NAT function of the virtual router doesn't work, probably, due to "net.bridge.bridge-nf-call-iptables=1".

I'm not sure where this is set. My dirty workaround is to place the following code in /etc/rc.local.

-----------
rc=1
while [[ $rc -ne 0 ]]; do
	sysctl net.bridge.bridge-nf-call-iptables | grep "1"
	rc=$?
	sleep 5
done
sysctl -w net.bridge.bridge-nf-call-iptables=0
sysctl -w net.bridge.bridge-nf-call-ip6tables=0
sysctl -w net.bridge.bridge-nf-call-arptables=0
-----------

My setup is:
# rpm -qa | grep quantum
openstack-quantum-linuxbridge-2012.2-2.1.el6.noarch
python-quantumclient-2.1.1-0.el6.noarch
python-quantum-2012.2-2.1.el6.noarch
openstack-quantum-2012.2-2.1.el6.noarch