System Administration Guide: IP Services

ICMP Router Discovery (RDISC) Protocol

Hosts use RDISC to obtain routing information from routers. Thus, when hosts are running RDISC, routers must also run another protocol, such as RIP, in order to exchange router information.

RDISC is implemented by in.routed, which should run on both routers and hosts. On hosts, in.routed uses RDISC to discover default routes from routers that advertise themselves through RDISC. On routers, in.routed uses RDISC to advertise default routes to hosts on directly-connected networks. See the in.routed(1M) man page and the gateways(4) man page.