The IESG has received a request from the Audio/Video Transport Core Maintenance WG (avtcore) to consider the following document: - 'Sending Multiple Media Streams in a Single RTP Session' <draft-ietf-avtcore-rtp-multi-stream-09.txt> as Proposed Standard The IESG plans to make a decision in the next few weeks, and solicits final comments on this action. Please send substantive comments to the ietf@ietf.org mailing lists by 2015-11-24. Exceptionally, comments may be sent to iesg@ietf.org instead. In either case, please retain the beginning of the Subject line to allow automated sorting. Abstract This memo expands and clarifies the behaviour of Real-time Transport Protocol (RTP) endpoints that use multiple synchronization sources (SSRCs). This occurs, for example, when an endpoint sends multiple media streams in a single RTP session. This memo updates RFC 3550 with regards to handling multiple SSRCs per endpoint in RTP sessions, with a particular focus on RTCP behaviour. It also updates RFC 4585 to update and clarify the calculation of the timeout of SSRCs and the inclusion of feedback messages. The file can be obtained via https://datatracker.ietf.org/doc/draft-ietf-avtcore-rtp-multi-stream/ IESG discussion can be tracked via https://datatracker.ietf.org/doc/draft-ietf-avtcore-rtp-multi-stream/ballot/ No IPR declarations have been submitted directly on this I-D.