where is the nomination flag in ice stun request packet?

Question

ref to this WebRTC - TURN and ICE functions it mentions that: "Regular Nomination The checks continue until there is at least one valid candidate pair. The controlling agent picks from the valid pairs and sends a second STUN request on that pair with a flag to tell the peer that this is the one that is nominated for use.

Aggressive Nomination The nomination flag is sent with every STUN request, once the first check succeeds ICE processing for that media stream is finished and a second STUN request is not needed."

here is the stun packet which I capture by wireshark, but it seems that there are no a flag named nomination flag, can somebody tell or any documents to ref, thanks

selbie selbie · Accepted Answer · 2019-12-25T08:58:18

Your link to the wireshark trace isn't actually linked in your question.

But, I suspect this is the ICE extension to STUN for the USE-CANDIDATE attribute discussed in the ICE RFC 8455

7.1.2.  USE-CANDIDATE

   The controlling agent MUST include the USE-CANDIDATE attribute in
   order to nominate a candidate pair (Section 8.1.1).  The controlled
   agent MUST NOT include the USE-CANDIDATE attribute in a Binding
   request.

8.1.1.  Nominating Pairs
   Once the controlling agent has picked a valid pair for nomination, it
   repeats the connectivity check that produced this valid pair (by
   enqueueing the pair that generated the check into the triggered-check
   queue), this time with the USE-CANDIDATE attribute
   (Section 7.2.5.3.4).  The procedures for the controlled agent are
   described in Section 7.3.1.5.

20.1.  STUN Attributes
   IANA has registered four STUN attributes:

      0x0024 PRIORITY
      0x0025 USE-CANDIDATE
      0x8029 ICE-CONTROLLED
      0x802A ICE-CONTROLLING

where is the nomination flag in ice stun request packet?

1 Answers