Subject: Re: [MMUSIC] 10 BUNDLE questions: If you add a m= line to an existing BUNDLE, can the recipient reject that BUNDLEing?

From: Christer Holmberg <[email-masked]>
Date: Thu, 25 Apr 2013 11:47:21 +0000

Hi,

> 8. If you add a m= line to an existing BUNDLE, can the recipient reject that BUNDLEing

Paul wrote the following:

     "If the change was to add a new m-line, that previously was not present, to the SDP *and* to the bundle, then answerer could potentially either:

     1) accept the m-line (non-zero port) and accept the bundling
     (matching mid-line to what was in the offer)"

Ok.

     "2) accept the m-line and reject the bundling (mid value
     for the rejected m-line omitted from the bundle group)

     3) reject the m-line (zero port) and reject the bundling. For better
     or worse, RFC5888 requires this behavior in the group line for
     rejected m-lines."

2) and 3) assume that we don't require, for any given bundle, that the number of m- lines in SDP answer matches the number of m- lines in the associated SDP offer. 

A fourth option would be:

     4) reject the m-line (zero port) and accept the bundling. 

But, as Paul indicated, RFC 5888 does not allow this, since it would mean having a mid value for an m- line with a zero port value.

A fifth option would be:

    5) reject the m-line (zero port) and REMOVE the whole BUNDLE group in which the m- line was offered.

This should of course be avoided, as the answerer would have to assign new individual port lines for each m- line that was previously part of the BUNDLE group. But, never the less, assuming we allow "deBUNDLING", it wouldn't be forbidden :)

I think we need a little more time to think about this also, so I will list it as an OPEN ISSUE. The outcome might also be dependent on whether we e.g. are going to update RFC 5888.

Regards,

Christer