The RTP Control Protocol (RTCP) Canonical Name (CNAME) is a
persistent transport-level identifier for an RTP endpoint. While the
Synchronization Source (SSRC) identifier of an RTP endpoint may
change if a collision is detected or when the RTP application is
restarted, its RTCP CNAME is meant to stay unchanged, so that RTP
endpoints can be uniquely identified and associated with their RTP
media streams. For proper functionality, RTCP CNAMEs should be
unique within the participants of an RTP session. However, the
existing guidelines for choosing the RTCP CNAME provided in the RTP
standard are insufficient to achieve this uniqueness. This memo
updates those guidelines to allow endpoints to choose unique RTCP
CNAMEs. [STANDARDS-TRACK]