During the test of ipv6 nat66 (NPT), a problem was discovered, that is, the prefix conversion is expected behavior, but the upstream cannot reply from its interface. The root cause is that vyos cannot respond to the NDP query request of the translated prefix. To support stateless NAT66 (NPT), it is necessary to support NDP proxy function.
The ndp proxy relies on the `ndppd` package to achieve
Nptv6 of Vyos 1.2 has the same problem
a)
Here are some examples
```
set service proxy-ndp interface <interface> prefix <prefix> mode auto # vyos defaults to static. valid values: "auto","static", and "iface"
set service proxy-ndp interface <interface> prefix <prefix> iface <interface> # Specify when the free mode is iface
set service proxy-ndp interface <interface> timeout 500 # Controls how long ndppd will wait for a Neighbor Advertisement message after forwarding a Neighbor Solicitation message according to the rule. This is in milliseconds, and the default value is 500
set service proxy-ndp interface <interface> ttl 30000 # This is in milliseconds, and the default value is 30000 (30 seconds)
set service proxy-ndp interface <interface> router <yes|no> # Controls if ndppd should send the router bit when sending Neighbor Advertisement messages. The default value here is yes.
```
b)
Here are some examples
```
set interface ethernet <interface> ipv6 proxy-ndp prefix <prefix> mode auto # vyos defaults to static. valid values: "auto","static", and "iface"
set interface ethernet <interface> ipv6 proxy-ndp prefix <prefix> iface <interface> # Specify when the free mode is iface
set interface ethernet <interface> ipv6 proxy-ndp timeout 500 # Controls how long ndppd will wait for a Neighbor Advertisement message after forwarding a Neighbor Solicitation message according to the rule. This is in milliseconds, and the default value is 500
set interface ethernet <interface> ipv6 proxy-ndp ttl 30000 # This is in milliseconds, and the default value is 30000 (30 seconds)
set interface ethernet <interface> ipv6 proxy-ndp router <yes|no> # Controls if ndppd should send the router bit when sending Neighbor Advertisement messages. The default value here is yes.
```
Decided to choose a plan
Document: https://manpages.debian.org/buster/ndppd/ndppd.conf.5.en.html