Support a list of clients (IPv6 addresses) to advertise to

[ihipop]

By default, the RA message will be sent using multicast so that every node on the link can use them

there is some security condition that I only want some of the devices to receive the RA message, and only these devices can have IPv6 address

The radvd and other production routers support this feature

• RADVD: If done, radvd does not send messages to the multicast addresses but to the configured unicast addresses only. Solicitations from other addresses are refused. This is similar to UnicastOnly but includes periodic messages and incoming client access configuration
• juniper: https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/solicit-router-advertisement-unicast.html

can we have this feature too?