ITU-T H.248.57 PDF

This Recommendation contains functionality to describe the use of the real-time transport protocol control protocol (RTCP) in ITU-T H.248-controlled media gateways. RTCP is used, for example, to monitor the quality of service and to convey information about the participants in an on-going real-time transport protocol (RTP) session.

[ITU-T H.248.1] assumes that when an RTP stream is specified in a local or remote descriptor, that an RTCP flow may be established according to the rules defined in section 11 of [IETF RFC 3550]. Additional ITU-T H.248/RTCP behaviour is defined in clause E.12.5 of [ITU-T H.248.1]. However, some media gateways may not instantiate an RTCP flow. For interoperability and for some applications such as firewall and network address translation (NAT), it is important for the media gateway controller (MGC) to be certain of the media gateway (MG) behaviour with respect to port allocation for RTCP. The "RTCP Handling Package" defined in this Recommendation provides a property to control this RTCP flow allocation.

This revision supports additional RTCP port allocation rules in context of RTP transport multiplexing.