6.1. Common Packetization Rules

All senders MUST enforce the following packetization rules, regardless of the packetization mode in use:

Coded slice NAL units or coded slice data partition NAL units belonging to the same coded picture (and thus sharing the same RTP timestamp value) MAY be sent in any order; however, for delay-critical systems, they SHOULD be sent in their original decoding order to minimize the delay. Note that the decoding order is the order of the NAL units in the bitstream.
Parameter sets are handled in accordance with the rules and recommendations given in Section 8.4.
MANEs MUST NOT duplicate any NAL unit except for sequence or picture parameter set NAL units, as neither this memo nor the H.264 specification provides means to identify duplicated NAL units. Sequence and picture parameter set NAL units MAY be duplicated to make their correct reception more probable, but any such duplication MUST NOT affect the contents of any active sequence or picture parameter set. Duplication SHOULD be performed on the application layer and not by duplicating RTP packets (with identical sequence numbers).

Senders using the non-interleaved mode and the interleaved mode MUST enforce the following packetization rule:

In an RTP translator, MANEs MAY convert single NAL unit packets into one aggregation packet, convert an aggregation packet into several single NAL unit packets, or mix both concepts. The RTP translator SHOULD take into account at least the following parameters: path MTU size, unequal protection mechanisms (e.g., through packet-based FEC according to RFC 5109 [18], especially for sequence and picture parameter set NAL units and coded slice data partition A NAL units), bearable latency of the system, and buffering capabilities of the receiver.

Informative note: An RTP translator is required to handle RTP Control Protocol (RTCP) as per RFC 3550.