You have a rogue IPv6 router on your network. It's not a host problem. It's along the lines of having a rogue DHCP server on your network but faster propagation.
It needs to be tracked down and disabled. You can use tcpdump (as root) to capture IPv6 RA and see who's doing it, and what's being advertised: tcpdump -ni eth0 'ip6 dst ff02::1' 06:48:48.044409 IP6 fe80::2d0:1ff:fedf:8400 > ff02::1: ICMP6, router advertisement, length 64 Then look at your IPv6 neighbor table for the MAC of that host: ip -6 neigh show fe80::2d0:1ff:fedf:8400 dev eth0 lladdr 00:d0:01:df:84:00 router REACHABLE Once you have the MAC, track it down and disable it. On a Cisco device "show mac address-table" (or "show mac-address-table" on older hardware). -- Ray Soucy Epic Communications Specialist Phone: +1 (207) 561-3526 Networkmaine, a Unit of the University of Maine System http://www.networkmaine.net/