# Router Advertisement

Router advertisements are [NDP](/glossary/n/ndp) discovery messages periodically sent by routers from each [multicast](/glossary/m/multicast) interface, announcing the [IP addresses ](/glossary/i/ip_address) of that interface.

In [NDP](/glossary/n/ndp), Router Advertisement packets have the type `134`, and can be triggered by a [Router Solicitation](/glossary/r/router_solicitation) message.