Please, add parameter router-preference to the ND configuration.
http://www.ietf.org/rfc/rfc4191.txt
If anybody have windows with "internet connection sharing", then advertise prefix to LAN with "medium" preference (i think). And ROS too. If switches is on lan without RA-guard (only small number of types have this function), this is big problem. Client then have prefix sometimes from windows, sometimes from ROS.
Thanks.