Subject: [MMUSIC] trickle-ice-sip: Usage of PRACK instead of INFO?

From: Christer Holmberg <[email-masked]>
Date: Fri, 13 Apr 2018 12:30:52 +0000

Hi,

Section 4.3.2 of draft-ietf-mmusic-trickle-ice-sip says:

   "In order to clear this ambiguity as soon as possible, the Answerer
   needs to retransmit the provisional response with the exponential
   back-off timers described in [RFC3262].  These retransmissions MUST
   cease on receipt of an INFO request carrying a 'trickle-ice' Info
   Package body or on transmission of the Answer in a 2xx response.
   This is similar to the procedure described in section 8.1.1 of
   [I-D.ietf-mmusic-ice-sip-sdp] except that the STUN binding Request is
   replaced by the INFO request."

Section 6.1.1 (the reference in the text above needs to be updated, as
indicated in a note) of draft-ietf-mmusic-ice-sip-sdp says:

   "It should be noted that the ICE specific optimization is very
   specific to provisional response carrying answers that start ICE
   processing and it is not a general technique for 1xx reliability.
   Also such an optimization SHOULD NOT be used if both agents support
   PRACK."

Q: Does the use-PRACK-if-both-agents-support-it apply to trickle-ICE too?
Section 4.3.1 describes the usage of PRACK, but there is no text regarding
whether one should use it if supported.

Regards,

Christer