Subject: [MMUSIC] Feedback requested on requirements

From: [email-masked] (Dale R. Worley)
Date: Thu, 25 Apr 2013 13:25:23 -0400 (EDT)

Here are two desiderata based on the limitations of existing
intermediate devices:

   DES C6  After offer/answer processing is finished, if the exchanged
      SDP is examined by a non-supporting SBC, the set of transport
      associations that it sees being specified for media exchange
      should be the set that are actually used for media transfer.

   This is needed because SBCs monitor the packet traffic on the
   transport associations and if no media is seen on one of the
   associations for a significant period of time, the SBC will tear down
   the call.  This desideratum was suggested by Hadriel Kaplan.

   DES C7  In a session description, no endpoint of a transport
      association may be used multiple times.

   Such duplication is not defined by [RFC4566].  Some SBCs do not
   support such duplication (ultimately, because it was not supported by
   [RFC2327]), and they reject SDP specifying duplicated transport
   association endpoints.  This desideratum was suggested by Cullen
   Jennings.

Dale

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 25 Apr 2013 17:31:00 +0000

Hi,

>Here are two desiderata based on the limitations of existing intermediate devices:
>

Well, this is not the case with BUNDLE, after the first O/A transaction. That's why there is a second O/A transaction.

>   association endpoints.  This desideratum was suggested by Cullen

I don't understand what is meant by this desiderata.

Regards,

Christer

---

From: [email-masked] (Dale R. Worley)
Date: Thu, 25 Apr 2013 15:35:20 -0400 (EDT)

> From: Christer Holmberg <[email-masked]>
>
> Well, this is not the case with BUNDLE, after the first O/A
> transaction. That's why there is a second O/A transaction.

That's true, which is an undesirable feature of BUNDLE.  (But we may
have to tolerate that undesirable feature in order to avoid an even
more undesirable feature.)

> I don't understand what is meant by this desiderata.

"Don't specify the same address/port in two m= lines."

Dale

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 25 Apr 2013 19:46:24 +0000

Hi,

> "Don't specify the same address/port in two m= lines."

Well, we do that in bundle (in the second offer).

Regards,

Christer