Comment 19 for bug 1302080

I've found that my suggested workaround to set /proc/sys/net/ipv6/conf/default/disable_ipv6=1 must only be run on the compute nodes. If it's run on the network nodes, then neutron-l3-agent flat out refuses to configure any IPv6 connectivity on the routers (even though the sysctl is set to 0 inside the qrouter network namespaces). See https://github.com/openstack/neutron/blob/master/neutron/common/ipv6_utils.py#L51-L64

However it seems that the setting is not necessary on the network nodes in any case, disable_ipv6 does get set to 1 on the linuxbridge devices there by something (I have not attempted to figure out what, exactly). It is only on the compute nodes that I need to set disable_ipv6=1 to avoid the global IPv6 address from being configured on the linuxbridges.