Not often needed, sometimes in cases of dedicated point-to-point links.
Usage:
# /sbin/ip -6 route add <ipv6network>/<prefixlength> dev <device> ¬ metric 1
Example:
# /sbin/ip -6 route add default dev eth0 metric 1
Metric ”1” is used here to be compatible with the metric used by route, because the default metric on using ”ip” is ”1024”.