gif interface not passing IPv6 packets

[Mark Atkinson]

>  root at tao[~]# ifconfig vr0 inet6 2a01:348:294::1 prefixlen 64 -alias
> root at tao[~]# ifconfig gif0 destroy
> root at tao[~]# ifconfig gif0
> ifconfig: interface gif0 does not exist
> Internet6:
> Destination                       Gateway                       Flags
> Netif Expire
> ::/96                             ::1                           UGRS
> lo0
> ::1                               ::1                           UH
> lo0
> ::ffff:0.0.0.0/96                 ::1                           UGRS
> lo0
> (deleted fe80, ff01, ff02 to save space)
> root at tao[~]# ifconfig gif0 create
> root at tao[~]# ifconfig gif0 tunnel 192.168.1.2 1.2.3.4
> root at tao[~]# ifconfig gif0 inet6 2abc::2 2abc::1 prefixlen 128
> root at tao[~]# netstat -nr -f inet6 | grep 2abc
> 2abc::1                           2abc::2                       UH
> gif0
> ff01:5::/32                       2abc::2                       U
> gif0
> ff02::%gif0/32                    2abc::2                       U
> gif0
> root at tao[~]# ping6 2abc::2
> ping6: UDP connect: No route to host
> 
> You see why I'm exceptionally confused now?!

Depending on your release you might need to add

ifconfig gif0 inet6 -ifdisabled