I presume this is coming from a host on your network rather than any router or switch. Track down the MAC address from the Sniffer, and re-configure the machine that is doing it.
If it turns out to be an Apple, let me know how you did it, 'cos I got the same problem. Nobody seems to know how to turn it off on an Apple. The best I could do was to isolate the Apples on their own VLAN give them routing for IPv4 only, and let them get on with it.
Kevin Dorrell
Luxembourg
