Is it possible to setup 6-to-4 tunnel between 2 systems without relay service?

I have 2 ipv6 capable ubuntu workstations: 192.168.1.221 and 192.168.1.133
on 192.168.1.221

//create tunnel
ip tunnel add tun6to4 mode sit ttl 30 remote any local 192.168.1.221
//bring it up
ip link set dev tun6to4 up
// add ipv6 address to tun6to4
ip -6 addr add 2002:c0a8:1dd::/48 dev tun6to4
// do the same sequence for 192.168.1.133
....
//add ipv6 route on 192.168.1.221 to 192.168.1.133
ip -6 route add 2002:c0a8:185::/48 dev tun6to4 metric 1
now, if i try to ping 192.168.1.133 from 192.168.1.221
ping6 -I tun6to4
i have "unknown host" error
Does my trying to setup tunnel without relay even make sense?
Thanks,
-V