Normative Change - SetActiveDest|
The client MUST NOT send a Set Active Destination request with a REMOTE-ADDRESS attribute over an unreliable link (ex: UDP) if an active destination is already set for that allocation.
If the client wishes to set a new active destination, it MUST wait until a successful response is received to a Set Destination Request removing the active destination. The client SHOULD then continue to wait for an additional period of up to 5 seconds until it is extremely unlikely that any data from the previous active destination might still arrive. Failure to wait could cause the client to receive and attribute late data forwarded by the TURN server to the wrong peer.
The client MAY wait a shorter period of time if the application has built-in addressing (such as the RTP Sender Source) that makes it unlikely the client would incorrectly attribute late data.