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Re: PRACK: Does non-200 response cease re-transmission ofreliable 18x?





Christer Holmberg wrote:

Also another question: Is the flows below valid according to recent arguments? UAC UAS |----invite(SDP)--->| |<--- 183(SDP)------| |-----prack(SDP)--->| |<--- 200(SDP)------|
      flow 1
Assuming the 200 is the PRACK response, yes.
UAC UAS |----invite-------->| |<--- 183-----------| |-----prack(SDP)--->| |<--- 200(SDP)------| flow 2
Not valid. If the INVITE does not contain SDP, a reliable answer must contain SDP. We are currently discussing whether the FIRST reliable response must contain SDP, or whether that rule can be related. But, that is a separate thread.

Hmm. That flow is a consequence of changing that rule that I had not previously considered.

Allowing flow 2 would cause all sorts of trouble. If the restriction on offer in first reliable provisional is to be relaxed it must be sure to state that the first offer must then be in *some* reliable provisional, and until that is sent there can be no offer sent another way (PRACK or UPDATE).

Just opening that question is enough to make me more concerned about relaxing the constraint.

	Paul

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