This commit introduces a new IPv6 API for positive reachability
confirmation, as specified in RFC 4861, Section 7.3.1. This feature aims
to enhance the effectiveness of the Neighbor Discovery mechanism, by
enabling upper-layer protocols to signal that the connection makes a
"forward progress".
The implementation within TCP serves as a reference. Compliance with
RFC 4861, especially Appendix E.1, was ensured by focusing on reliable
handshake and acknowledgment of new data transmissions.
Though initially integrated with TCP, the API is designed for broader
applicability. For example, it might be used by some UDP-based protocols
that can indicate two-way communication progress.
Signed-off-by: Łukasz Duda <lukasz.duda@nordicsemi.no>
5273af6ba8