IPv6-to-IPv6 Network Prefix Translation (NPTv6) performs
a stateless, static translation of one IPv6 prefix to another IPv6
prefix (port numbers are not changed). There are four primary benefits
You can prevent the asymmetrical routing problems that result
from Provider Independent addresses being advertised from multiple datacenters.
NPTv6 allows more specific routes to be advertised so that return
traffic arrives at the same firewall that transmitted the traffic.
Private and public addresses are independent; you can change
one without affecting the other.