/etc/network/interfaces.d/60-ipv6-asd
iface eth0 inet6 static
address 2001:41d0:701:1100::35ab
netmask 128
post-up /sbin/ip -f inet6 route add 2001:41d0:701:1100::1 dev eth0
post-up /sbin/ip -f inet6 route add default via 2001:41d0:701:1100::1
pre-down /sbin/ip -f inet6 route del 2001:41d0:701:1100::1 dev eth0
pre-down /sbin/ip -f inet6 route del default via 2001:41d0:701:1100::1