Hi
Juniper in Junos call such address MARTIANS and they are not forwarded
shoiw route martians table inet6.0... shows the addresses blocked
but if you want to use them, then you can delete such address under [edit routing options]
[edit routing-options rib inet6.0]
user@R1# set martians 2001:db8::/32 orlonger allow
regards
alexander