> -----Original Message----- > From: Arun Punj [mailto:[EMAIL PROTECTED] > Sent: Tuesday, October 23, 2007 8:10 AM > To: [email protected]; [EMAIL PROTECTED] > Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: SDES RFC4568 usage clarification > > Folks, > > > > A simple clarification on RFC4568 usage. > > > > User [EMAIL PROTECTED] wants to make a call(audio/video) to > [EMAIL PROTECTED] Alice would like media between Alice&Bob to > be encrypted, but would like the call to go through even if > the encryption between Alice&Bob is not possible.
draft-ietf-mmusic-sdp-capability-negotiation solves that exact problem, and works with forking (many of your examples below will not work as desired with forking). http://tools.ietf.org/html/draft-ietf-mmusic-sdp-capability-negotiation -d > I am > interested in figuring out how the SDP exchange between Alice > and Bob would proceed, for the two cases: > > 1. Bob supports encryption > > 2. Bob does not support encryption. > > > > Various Options which I can think of are: > > > > 1. Alice sends INVITE to bob with SDP > > m = audio 30000 RTP/SAVP 0 > > a = crypto .... > > m = video 30000 RTP/SAVP 32 > > a = crypto.... > > > > If bob supports encryption no problem. > > > > If bob does not support encryption or specifically if it > does not support RTP/SAVP profile it will be send back an OK > with following SDP > > m=audio 0 RTP/SAVP0 > > a=inactive > > m = video 0 RTP/SAVP > > a=inactive > > > > At this point Alice does not know that bob does not support > SAVP or if there is something else wrong with the crypto > parameters. Is Alice supposed to send another RE-INVITE with > RTP/AVP profile ? > > > > 2. Alice sends an INVITE to bob with SDP > > m=audio 30000 RTP/AVP 0 > > m=video 30002 RTP/AVP 32 > > m =audio 30004 RTP/SAVP 0 > > a = crypto: xxxx > > m=video 30006 RTP/SAVP 32 > > a=crypto: xxxxx > > > > In this case, if bob does not support encryption he could > pick up the right two streams ( maybe). However, if bob > supports encryption and a=crypto attribute how does he know that > > m=audio 30000 RTP/AVP 0 > > and > > m=audio 30004 RTP/SAVP 0 > > really refer to the same media stream. > > > > > > 3. Alice sends an INVITE to bob with SDP > > > > m = audio 30000 RTP/SAVP 0 > > a = crypto .... > > m = video 30000 RTP/SAVP 32 > > a = crypto.... > > > > And bobs UA sends a 4xx media unacceptable message, and alice > tries again without encryption. > > > > > > Your comments will be helpful. > > > > thanks > > Arun > > _______________________________________________ Sip mailing list https://www1.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
