University of Applied Sciences Bonn-Rhein-Sieg Linaro This document specifies a return routability check for use in context of the Connection ID (CID) construct for the Datagram Transport Layer Security (DTLS) protocol versions 1.2 and 1.3. Discussion Venues This note is to be removed before publishing as an RFC. Discussion of this document takes place on the Transport Layer Security Working Group mailing list (tls@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/tls/. Source for this draft and an issue tracker can be found at https://github.com/tlswg/dtls-rrc.