8.2 Collisions and Loops

ccRTP performs loop detection (following 8.2 in RFC 3550, though the algorithm in ccRTP differs is structure because of two reasons:

• ccRTP holds a table of source for which some packet has been received, instead of a table with all the sources in the session (i.e. the local source is not included in the table unless it sends packets to itself).
• RTP and RTCP packets are handled separately whereas the algorithm in 8.2 treats both.

  Note that the first two conditions in 8.2 (creating new source entries and setting source transport address) are handled in the SSRC bookkeeping methods rather than mixing them with the real collisions and loop handling.

  Unlike the algorithm given in 8.2, the ccRTP algorithm detects the very rare case when two sources on the same host use the same SSRC identifier and the first RTP packet for that identifier is received from one source and the first RTCP is received from the other.