Subject: [MMUSIC] [mmusic] #1: How to reject a loopback offer

From: "mmusic issue tracker" <[email-masked]>
Date: Tue, 22 Nov 2011 08:42:51 -0000

#1: How to reject a loopback offer

 There is an inconsistency and confusion around how to "reject" a loopback
 SDP offer.  Two comments were received regarding this:

 -------------------
 From Magnus:

 Section 5.4:

 If an answerer wishes to accept the loopback request it MUST
    include both the loopback mode and loopback type attribute in the
    answer. When a stream is offered with the loopback-source
    attribute, the corresponding stream in the response MUST be
    loopback-mirror and vice versa, provided that answerer is capable
    of supporting the requested loopback-type.

 This seems to be in partial conflict with 5.4.1. As my impression of the
 above, is that if you don't want to accept, you don't include the
 attributes. But 5.4.1 says that it should be included but the port set
 to 0.

 -------------------
 From Miguel:

 The note at the end of Section 10.3 reads:

   NOTE: Loopback request may be rejected by either not including the
   loopback mode attribute (for backward compatibility) or setting the
   media port number to zero, or both, in the response.

 First, I don't like this note here, because it may induce to double
 specification, specially since you have Section 5.4 that describes how to
 reject a loopback request.

 And actually, here you have double incongruent specification. Section
 5.4.1 only offers one mechanism for rejecting a session: setting the port
 to zero like in regular SDP. Nothing is written about rejecting a session
 by not including the loopback mode attribute.

 Not including a loopback mode attribute in the answer is not a rejection,
 it is merely a session with no support for the loopback feature, but the
 session is established.

 I recommend to delete this note.

-- 
--------------------------+------------------------------------------------
 Reporter:  hkaplan@…     |      Owner:  draft-ietf-mmusic-media-loopback@…
     Type:  defect        |     Status:  new
 Priority:  major         |  Milestone:  milestone1
Component:  media-        |    Version:  1.0
  loopback                |   Keywords:
 Severity:  In WG Last    |
  Call                    |
--------------------------+------------------------------------------------

Ticket URL: <http://trac.tools.ietf.org/wg/mmusic/trac/ticket/1>
mmusic <http://tools.ietf.org/mmusic/>