Following up on my own question... I took at look at the code (/usr/src/sys/netinet6/nd6.c line 1185) where this message is printed. From what I can tell, the message is being printed only because the interface (stf0) is an "AF_INET6" rather than a "AF_LINK".
It's not clear to me whether there's even a real error occurring here - and it turns out that I am able to communicate with other IPv6 nodes (both 6to4 and native) just fine. Can anyone who's familiar with this code confirm whether or not this message is just a red herring? Ross. To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-net" in the body of the message