Boeing Research & Technology Google The IPv6 Neighbor Discovery (ND) protocol allows nodes to discover neighbors on the same link. Router Advertisement (RA) messages can also convey routing information by including a non-zero (default) Router Lifetime, and/or Route Information Options (RIOs). This document specifies backward-compatible extensions that permit nodes to include RIOs in other IPv6 ND messages to support the discovery of more-specific routes among neighbors on the link.