Virtual Interim CLUE Signalling discussion Robert Hansen 2014/05/29

-01 Document cleanup Revised terminology Calls are CLUE-enabled or not Devices are CLUE-capable or not (irrespective of whether call is CLUE-enabled) Moved encoding information outside of SDP initial offer section Given draft recommends initial offer does not contain encodings, was a strange place to define them

Syntax change Feature tag: ‘sip.telepresence’ changed to ‘sip.clue’ Group syntax: TELEPRESENCE changed to CLUE

CLUE group restrictions CLUE group must have one (and only one) mid related to a data channel Previously could a CLUE group with no data channel association Explicitly forbids multiple CLUE groups until someone publishes a way to do it

CLUE-controlled media Restriction on sending media on CLUE-controlled m-lines until negotiated in CLUE as well Is there a better term for what can’t be sent than ‘media’? Explicitly mandates that non-media exchanges like DTLS and ICE must be done as normal No text on RTCP yet – if channel is active should be sent as normal(?)

CLUE/SDP state machine interaction Some changes in call state require CLUE and SDP changes and hence are non-atomic CLUE and SDP state machines are independent Participant must cope with transitory states with inconsistent information CLUE-controlled media unless both CLUE and SDP information available

CLUE/SDP state machine interaction MUST NOT delay ongoing SDP exchange due to CLUE state MAY delay initiating new SDP exchange MUST NOT delay any mandatory CLUE transitions (for provider/consumer/participant state machines) due to SDP state MAY delay “CONF COMPLETED->PREPARING ADV” or “READY TO CONF->TRYING” (send new ADVERTISE or CONFIGURE) based on SDP state

CLUE/SDP state machine recommendations SHOULD ensure that any inconsistencies are transitory Make this a MUST? Recommends no ‘speculative’ requests are made Eg, don’t request anything until details are available in both CLUE and SDP May require more O/As Send changes in CLUE before SDP Minimises SDP O/As needed

CLUE/SDP state machine recommendations Adding stream Alice Bob CLUE ADVERISEMENT SDP Offer SDP Answer May be simultaneous CLUE CONFIGURE Media starts

CLUE/SDP state machine recommendations Removing stream Alice Bob CLUE ADVERISEMENT Media stops CLUE CONFIGURE No ordering recommendation SDP Offer SDP Answer