The Router Advertisement Daemon (radvd) is an open-source software product that implements link-local advertisements of IPv6

IPv6

Internet Protocol version 6 is a version of the Internet Protocol . It is designed to succeed the Internet Protocol version 4...

 router addresses and IPv6 routing prefixes using the Neighbor Discovery Protocol

Neighbor Discovery Protocol

The Neighbor Discovery Protocol is a protocol in the Internet Protocol Suite used with Internet Protocol Version 6 . It operates in the Link Layer of the Internet model and is responsible for address autoconfiguration of nodes, discovery of other nodes on the link, determining the Link Layer...

 (NDP) as specified in RFC 2461. The Router Advertisement Daemon is used by system administrators in stateless autoconfiguration methods of network hosts on Internet Protocol

Internet Protocol

The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...

 version 6 networks.

When IPv6 hosts configure their network interfaces, they broadcast router solicitation (RS) requests onto the network to discover available routers. The radvd software answers requests with router advertisement (RA) messages. In addition, radvd periodically broadcasts RA packets to the attached link to update network hosts. The router advertisement messages contain the routing prefix used on the link, the link maximum transmission unit

Maximum transmission unit

In computer networking, the maximum transmission unit of a communications protocol of a layer is the size of the largest protocol data unit that the layer can pass onwards. MTU parameters usually appear in association with a communications interface...

(MTU), and the address of the responsible default router.

Radvd also supports the recursive DNS server (RDNSS) and DNS search list (DNSSL) options for NDP published in RFC 6106.