[MMUSIC] BUNDLE and separate RTP and RTCP ports even when rtcp-mux is used

[Christer Holmberg <[e-mail]>]

Hi,

A question related to RTP/RTCP multiplexing with BUNDLE.

BUNDLE allows the usage of identical port numbers for multiple m- lines. It also
expects a remote endpoint that does not support BUNDLE to send media associated
with multiple m- lines to that single port, even if the remote endpoint itself will use
different ports for each m- line.

In addition, the BUNDLE client can also multiplex RTP and RTCP, using the a=rtcp-mux attribute.

However, RFC 5761 says that one must be able to receive RTCP on the default RTCP port,
if the remote endpoint does not support a=rtcp-mux attribute.

But, even if the remote endpoint does not support RTCP/RTP muxing, the question is whether
the local endpoint could still use the same port for RTCP/RTP - and expect the remote endpoint
to send both RTP and RTCP to that single port (even if the remote endpoint itself uses different
ports for RTP and RTCP). In addition to the a=rtcp-mux attribute, the local endpoint
would use the a=rtcp attribute, containing the RTP port value.

That would also, when ICE is used, prevent the local endpoint from having to reserve
RTCP specific candidate ports.

Regards,

Christer