I am trying to figure out exactly what RA-guard is. I have guessed based on reading other messages that it is something to do with IPv6 router advertisements, but as it's now a default in quite a few roles I wanted to get into a bit more detail about what it is and why it's set to deny. This is the acl;
ip access-list session ra-guard
ipv6 user any icmpv6 rtr-adv deny
Can someone explain what this is and what it's function is in the configuration? The rule itself is interesting to me as well as it seems this is the only place that references rtr-adv, which I am assuming is icmpv6 router advertisements, so some idea of how that works would be great as well.