3.1.5.21.4 Ice-mismatch attributes

According to [IETFDRAFT-ICENAT-19], this attribute, when present in an answer, indicates that the agent that sends the offer contains a default destination for a media component that did not have a corresponding candidate attribute.

This protocol does not support this attribute. It SHOULD NOT<39> generate an answer with this attribute. If received as an answer to an offer, this protocol SHOULD ignore this attribute.

For offers that are generated by this protocol, the default destination for a media component SHOULD<40> have a corresponding candidate attribute.