[MMUSIC] Bundle offer with different ports - where to expect media?

Christer Holmberg <christer.holmberg@ericsson.com> Mon, 20 May 2013 11:43 UTC

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From: Christer Holmberg <christer.holmberg@ericsson.com>
To: "mmusic@ietf.org" <mmusic@ietf.org>
Thread-Topic: Bundle offer with different ports - where to expect media?
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Date: Mon, 20 May 2013 11:43:30 +0000
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Subject: [MMUSIC] Bundle offer with different ports - where to expect media?
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Currently BUNDLE defines that the first offer is sent with separate port numbers (later, if the answerer has indicated support of BUNDLE, the offerer will send a second offer, with identical port numbers).

Some people have indicated that the offerer shall be able to receive data already when the first offer has been sent. The question is on which port(s) it needs to be able to receive media.

-          Some have suggested the port of the first non-zero m- line within the offered bundle group.

-          Some have suggested ANY port

The issue with assuming the first non-zero m- line is that the answerer in the answer may reject it (put the port to zero), or remove it from the bundle group (which people seem to want to allow). In both cases it would be strange to assume the first m- line.

Now, in case e.g. ICE is used, the offerer will be able to send the second offer before any media is received to begin with. But, the offerer could still receive STUN connectivity checks on any of the ports, until the second offer has been sent.

We need text in BUNDLE about this, so comments/inputs are welcome :)