Re: [MMUSIC] Feedback requested on requirements

[[e-mail] (Dale R. Worley)]

> From: Christer Holmberg <[e-mail]>
>
> >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.
> 
> 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.)

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

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

Dale