Ericsson Google Cisco This specification defines a new Session Description Protocol (SDP) Grouping Framework extension, 'BUNDLE'. The extension can be used with the SDP Offer/Answer mechanism to negotiate the usage of a single transport (5-tuple) for sending and receiving media described by multiple SDP media descriptions ("m=" sections). Such transport is referred to as a BUNDLE transport, and the media is referred to as bundled media. The "m=" sections that use the BUNDLE transport form a BUNDLE group. This specification updates RFC 3264, to allow assigning a zero port value to a "m=" section without meaning that the media described by the "m=" section is disabled or rejected. This specification defines a new RTP Control Protocol (RTCP) source description (SDES) item and a new RTP header extension that van be used to correlate bundled RTP/RTCP packets with their appropriate "m=" section.