Subject: [MMUSIC] SIP-SDP: Verify decision made in Seoul regarding non-supported transport in m- line of answer

From: Christer Holmberg <[email-masked]>
Date: Fri, 13 Jan 2017 11:32:27 +0000

Hi,

In Seoul we discussed a number of issues related to ICE-SDP. We made some decisions, and I got action points to verify one of those on the list.

The associated slides can be found here:

https://www.ietf.org/proceedings/97/slides/slides-97-mmusic-ice-sip-sdp-00.pdf

The issue (slides 4-6) was when an answerer receives an offer with a m- line transport that it doesn’t support. The current O/A rules say that the transport in the answer must match the transport in the offer.

However, if ICE is used, there may be transports (offered using ICE candidates) that the answerer DOES support.

Based on the discussions, there was strong consensus to go for Alt#2, which was allowing a transport in the m- line of the answer even if the answerer doesn’t support it, as ICE candidates will be used to determine the transport.

Does anyone object to Alt#2?

Regards,

Christer