This has been fixed in a redhat errata:RHBA-2015:1289 (Possibly paywall).
In summary - the fix is to move the configuration from
Delete the offending lines from
sed -i '/net.bridge.bridge-nf-call-/d' /etc/sysctl.conf
And add the behavior to your
# Disable netfilter on bridges when the bridge module is loaded
install bridge /sbin/modprobe --ignore-install bridge && /sbin/sysctl -q -w net.bridge.bridge-nf-call-arptables=0 net.bridge.bridge-nf-call-iptables=0 net.bridge.bridge-nf-call-ip6tables=0
Which will set the values correctly upon load of the bridge module, or simply update your rpms to versions
Both are present by default in RHEL 6.8
If anyone is interested in the history behind this, it's present here with an explanation there.